Polymers

13 pages, 3193 KiB

Open AccessEditor’s ChoiceArticle

Melt-Mixed PP/MWCNT Composites: Influence of CNT Incorporation Strategy and Matrix Viscosity on Filler Dispersion and Electrical Resistivity

by Petra Pötschke, Fanny Mothes, Beate Krause and Brigitte Voit

Polymers 2019, 11(2), 189; https://doi.org/10.3390/polym11020189 - 22 Jan 2019

Cited by 38 | Viewed by 5467

Abstract

Small-scale melt mixing was performed for composites based on polypropylene (PP) and 0.5–7.5 wt % multiwalled carbon nanotubes (MWCNT) to determine if masterbatch (MB) dilution is a more effective form of nanofiller dispersion than direct nanotube incorporation. The methods were compared using composites [...] Read more.

Small-scale melt mixing was performed for composites based on polypropylene (PP) and 0.5–7.5 wt % multiwalled carbon nanotubes (MWCNT) to determine if masterbatch (MB) dilution is a more effective form of nanofiller dispersion than direct nanotube incorporation. The methods were compared using composites of five different PP types, each filled with 2 wt % MWCNTs. After the determination of the specific mechanical energy (SME) input in the MB dilution process, the direct-incorporation mixing time was adjusted to achieve comparable SME values. Interestingly, the electrical resistivity of MB-prepared samples with 2 wt % MWCNTs was higher than that of those prepared using direct incorporation—despite their better dispersion—suggesting more pronounced MWCNT shortening in the two-step procedure. In summary, this study on PP suggests that the masterbatch approach is suitable for the dispersion of MWCNTs and holds advantages in nanotube dispersion, albeit at the cost of slightly increased electrical resistivity. Full article

(This article belongs to the Special Issue Polymer-CNT Nanocomposites)

► Show Figures

Graphical abstract

32 pages, 2801 KiB

Open AccessEditor’s ChoiceReview

Conductive Polymer Composites from Renewable Resources: An Overview of Preparation, Properties, and Applications

by Yao Huang, Semen Kormakov, Xiaoxiang He, Xiaolong Gao, Xiuting Zheng, Ying Liu, Jingyao Sun and Daming Wu

Polymers 2019, 11(2), 187; https://doi.org/10.3390/polym11020187 - 22 Jan 2019

Cited by 120 | Viewed by 15749

Abstract

This article reviews recent advances in conductive polymer composites from renewable resources, and introduces a number of potential applications for this material class. In order to overcome disadvantages such as poor mechanical properties of polymers from renewable resources, and give renewable polymer composites [...] Read more.

This article reviews recent advances in conductive polymer composites from renewable resources, and introduces a number of potential applications for this material class. In order to overcome disadvantages such as poor mechanical properties of polymers from renewable resources, and give renewable polymer composites better electrical and thermal conductive properties, various filling contents and matrix polymers have been developed over the last decade. These natural or reusable filling contents, polymers, and their composites are expected to greatly reduce the tremendous pressure of industrial development on the natural environment while offering acceptable conductive properties. The unique characteristics, such as electrical/thermal conductivity, mechanical strength, biodegradability and recyclability of renewable conductive polymer composites has enabled them to be implemented in many novel and exciting applications including chemical sensors, light-emitting diode, batteries, fuel cells, heat exchangers, biosensors etc. In this article, the progress of conductive composites from natural or reusable filling contents and polymer matrices, including (1) natural polymers, such as starch and cellulose, (2) conductive filler, and (3) preparation approaches, are described, with an emphasis on potential applications of these bio-based conductive polymer composites. Moreover, several commonly-used and innovative methods for the preparation of conductive polymer composites are also introduced and compared systematically. Full article

(This article belongs to the Special Issue Renewable Polymer Composites)

► Show Figures

Figure 1

14 pages, 2389 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Dye and Cr^(VI) Degradation Using a Metal-Free Polymeric g-C₃N₄ Synthesized from Solvent-Treated Urea

by Chechia Hu, Yi-Ching Chu, Yan-Ru Lin, Hung-Chun Yang and Ke-Hsuan Wang

Polymers 2019, 11(1), 182; https://doi.org/10.3390/polym11010182 - 21 Jan 2019

Cited by 37 | Viewed by 7019

Abstract

The development of visible-light-driven polymeric g-C₃N₄ is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C₃N₄ from urea treated with various solvents such [...] Read more.

The development of visible-light-driven polymeric g-C₃N₄ is in response to an emerging demand for the photocatalytic dye degradation and reduction of hexavalent chromium ions. We report the synthesis of g-C₃N₄ from urea treated with various solvents such as methanol, ethanol, and ethylene glycol. The samples were characterized and the Williamson–Hall method was applied to investigate the lattice strain of the samples. The activity of the samples was evaluated by observing the degradation of methyl orange and K₂Cr₂O₇ solution under light irradiation. Photocatalytic reaction kinetics were determined as pseudo-first-order and zero-order for the degradation of methyl orange and reduction of hexavalent chromium, respectively. Due to the inhibited charge separation resulting from the small lattice strain, reduced crystal imperfection, and sheet-like structure, g-C₃N₄ obtained from ethanol-treated urea exhibited the highest activity among the evaluated samples. Full article

(This article belongs to the Special Issue Polymeric Photocatalysts and Gas Sensors)

► Show Figures

Graphical abstract

16 pages, 6428 KiB

Open AccessEditor’s ChoiceArticle

High Response CO Sensor Based on a Polyaniline/SnO₂ Nanocomposite

by Kai-Syuan Jian, Chi-Jung Chang, Jerry J. Wu, Yu-Cheng Chang, Chien-Yie Tsay, Jing-Heng Chen, Tzyy-Leng Horng, Gang-Juan Lee, Lakshmanan Karuppasamy, Sambandam Anandan and Chin-Yi Chen

Polymers 2019, 11(1), 184; https://doi.org/10.3390/polym11010184 - 21 Jan 2019

Cited by 52 | Viewed by 5811

Abstract

A polyaniline (PANI)/tin oxide (SnO₂) composite for a CO sensor was fabricated using a composite film composed of SnO₂ nanoparticles and PANI deposition in the present study. Tin oxide nanoparticles were synthesized by the sol-gel method. The SnO₂ nanoparticles [...] Read more.

A polyaniline (PANI)/tin oxide (SnO₂) composite for a CO sensor was fabricated using a composite film composed of SnO₂ nanoparticles and PANI deposition in the present study. Tin oxide nanoparticles were synthesized by the sol-gel method. The SnO₂ nanoparticles provided a high surface area to significantly enhance the response to the change in CO concentration at low operating temperature (<75 °C). The excellent sensor response was mainly attributed to the relatively good properties of PANI in the redox reaction during sensing, which produced a great resistance difference between the air and CO gas at low operating temperature. Therefore, the combination of n-type SnO₂ nanoparticles with a high surface area and a thick film of conductive PANI is an effective strategy to design a high-performance CO gas sensor. Full article

(This article belongs to the Special Issue Polymeric Photocatalysts and Gas Sensors)

► Show Figures

Figure 1

11 pages, 2726 KiB

Open AccessEditor’s ChoiceArticle

A Parallel Bicomponent TPU/PI Membrane with Mechanical Strength Enhanced Isotropic Interfaces Used as Polymer Electrolyte for Lithium-Ion Battery

by Ming Cai, Jianwei Zhu, Chaochao Yang, Ruoyang Gao, Chuan Shi and Jinbao Zhao

Polymers 2019, 11(1), 185; https://doi.org/10.3390/polym11010185 - 21 Jan 2019

Cited by 51 | Viewed by 8046

Abstract

In this work, a side-by-side bicomponent thermoplastic polyurethane/polyimide (TPU/PI) polymer electrolyte prepared with side-by-side electrospinning method is reported for the first time. Symmetrical TPU and PI co-occur on one fiber, and are connected by an interface transition layer formed by the interdiffusion of [...] Read more.

In this work, a side-by-side bicomponent thermoplastic polyurethane/polyimide (TPU/PI) polymer electrolyte prepared with side-by-side electrospinning method is reported for the first time. Symmetrical TPU and PI co-occur on one fiber, and are connected by an interface transition layer formed by the interdiffusion of two solutions. This structure of the as-prepared TPU/PI polymer electrolyte can integrate the advantages of high thermal stable PI and good mechanical strength TPU, and mechanical strength is further increased by those isotropic interface transition layers. Moreover, benefiting from micro-nano pores and the high porosity of the structure, TPU/PI polymer electrolyte presents high electrolyte uptake (665%) and excellent ionic conductivity (5.06 mS·cm⁻¹) at room temperature. Compared with PE separator, TPU/PI polymer electrolyte exhibited better electrochemical stability, and using it as the electrolyte and separator, the assembled Li/LiMn₂O₄ cell exhibits low inner resistance, stable cyclic and notably high rate performance. Our study indicates that the TPU/PI membrane is a promising polymer electrolyte for high safety lithium-ion batteries. Full article

(This article belongs to the Special Issue Electrospun Nanofibers: Theory and Its Applications)

► Show Figures

Graphical abstract

14 pages, 3104 KiB

Open AccessEditor’s ChoiceArticle

Design and Compressive Behavior of a Photosensitive Resin-Based 2-D Lattice Structure with Variable Cross-Section Core

by Shuai Li, Jiankun Qin, Bing Wang, Tengteng Zheng and Yingcheng Hu

Polymers 2019, 11(1), 186; https://doi.org/10.3390/polym11010186 - 21 Jan 2019

Cited by 28 | Viewed by 4724

Abstract

This paper designed and manufactured photosensitive resin-based 2-D lattice structures with different types of variable cross-section cores by stereolithography 3D printing technology (SLA 3DP). An analytical model was employed to predict the structural compressive response and failure types. A theoretical calculation was performed [...] Read more.

This paper designed and manufactured photosensitive resin-based 2-D lattice structures with different types of variable cross-section cores by stereolithography 3D printing technology (SLA 3DP). An analytical model was employed to predict the structural compressive response and failure types. A theoretical calculation was performed to obtain the most efficient material utilization of the 2-D lattice core. A flatwise compressive experiment was performed to verify the theoretical conclusions. A comparison of theoretical and experimental results showed good agreement for structural compressive response. Results from the analytical model and experiments showed that when the 2-D lattice core was designed so that R/r = 1.167 (R and r represent the core radius at the ends and in the middle), the material utilization of the 2-D lattice core improved by 13.227%, 19.068%, and 22.143% when n = 1, n = 2, and n = 3 (n represents the highest power of the core cross-section function). Full article

(This article belongs to the Special Issue 2D Polymers and Composites: Preparation, Characterization and Application)

► Show Figures

Figure 1

18 pages, 6363 KiB

Open AccessEditor’s ChoiceArticle

Biocompatibility of Small-Diameter Vascular Grafts in Different Modes of RGD Modification

by Larisa V. Antonova, Vladimir N. Silnikov, Victoria V. Sevostyanova, Arseniy E. Yuzhalin, Lyudmila S. Koroleva, Elena A. Velikanova, Andrey V. Mironov, Tatyana S. Godovikova, Anton G. Kutikhin, Tatiana V. Glushkova, Inna Yu. Serpokrylova, Evgeniya A. Senokosova, Vera G. Matveeva, Mariam Yu. Khanova, Tatiana N. Akentyeva, Evgeniya O. Krivkina, Yulia A. Kudryavtseva and Leonid S. Barbarash

Polymers 2019, 11(1), 174; https://doi.org/10.3390/polym11010174 - 18 Jan 2019

Cited by 23 | Viewed by 5101

Abstract

Modification with Arg-Gly-Asp (RGD) peptides is a promising approach to improve biocompatibility of small-calibre vascular grafts but it is unknown how different RGD sequence composition impacts graft performance. Here we manufactured 1.5 mm poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) grafts modified by distinct linear or cyclic [...] Read more.

Modification with Arg-Gly-Asp (RGD) peptides is a promising approach to improve biocompatibility of small-calibre vascular grafts but it is unknown how different RGD sequence composition impacts graft performance. Here we manufactured 1.5 mm poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) grafts modified by distinct linear or cyclic RGD peptides immobilized by short or long amine linker arms. Modified vascular prostheses were tested in vitro to assess their mechanical properties, hemocompatibility, thrombogenicity and endothelialisation. We also implanted these grafts into rat abdominal aortas with the following histological examination at 1 and 3 months to evaluate their primary patency, cellular composition and detect possible calcification. Our results demonstrated that all modes of RGD modification reduce ultimate tensile strength of the grafts. Modification of prostheses does not cause haemolysis upon the contact with modified grafts, yet all the RGD-treated grafts display a tendency to promote platelet aggregation in comparison with unmodified counterparts. In vivo findings identify that cyclic Arg-Gly-Asp-Phe-Lys peptide in combination with trioxa-1,13-tridecanediamine linker group substantially improve graft biocompatibility. To conclude, here we for the first time compared synthetic small-diameter vascular prostheses with different modes of RGD modification. We suggest our graft modification regimen as enhancing graft performance and thus recommend it for future use in tissue engineering. Full article

(This article belongs to the Special Issue Functional Polymers for Biomedicine)

► Show Figures

Graphical abstract

22 pages, 7284 KiB

Open AccessEditor’s ChoiceReview

Recent Advances in Organic Thermoelectric Materials: Principle Mechanisms and Emerging Carbon-Based Green Energy Materials

by Yinhang Zhang, Young-Jung Heo, Mira Park and Soo-Jin Park

Polymers 2019, 11(1), 167; https://doi.org/10.3390/polym11010167 - 18 Jan 2019

Cited by 92 | Viewed by 14282

Abstract

Thermoelectric devices have recently attracted considerable interest owing to their unique ability of converting heat to electrical energy in an environmentally efficient manner. These devices are promising as alternative power generators for harvesting electrical energy compared to conventional batteries. Inorganic crystalline semiconductors have [...] Read more.

Thermoelectric devices have recently attracted considerable interest owing to their unique ability of converting heat to electrical energy in an environmentally efficient manner. These devices are promising as alternative power generators for harvesting electrical energy compared to conventional batteries. Inorganic crystalline semiconductors have dominated the thermoelectric material fields; however, their application has been restricted by their intrinsic high toxicity, fragility, and high cost. In contrast, organic thermoelectric materials with low cost, low thermal conductivity, easy processing, and good flexibility are more suitable for fabricating thermoelectric devices. In this review, we briefly introduce the parameters affecting the thermoelectric performance and summarize the most recently developed carbon-material-based organic thermoelectric composites along with their preparation technologies, thermoelectric performance, and future applications. In addition, the p- and n-type carbon nanotube conversion and existing challenges are discussed. This review can help researchers in elucidating the recent studies on carbon-based organic thermoelectric materials, thus inspiring them to develop more efficient thermoelectric devices. Full article

► Show Figures

Graphical abstract

15 pages, 5699 KiB

Open AccessEditor’s ChoiceArticle

Mechanical and Water-Resistant Properties of Eco-Friendly Chitosan Membrane Reinforced with Cellulose Nanocrystals

by Haiquan Mao, Chun Wei, Yongyang Gong, Shiqi Wang and Wenwen Ding

Polymers 2019, 11(1), 166; https://doi.org/10.3390/polym11010166 - 18 Jan 2019

Cited by 68 | Viewed by 8778

Abstract

Environmentally benign and biodegradable chitosan (CS) membranes have disadvantages such as low mechanical strength, high brittleness, poor heat resistance and poor water resistance, which limit their applications. In this paper, home-made cellulose nanocrystals (CNC) were added to CS to prepare CNC/CS composite membranes [...] Read more.

Environmentally benign and biodegradable chitosan (CS) membranes have disadvantages such as low mechanical strength, high brittleness, poor heat resistance and poor water resistance, which limit their applications. In this paper, home-made cellulose nanocrystals (CNC) were added to CS to prepare CNC/CS composite membranes through mechanical mixing and solution casting approaches. The effects of CNC dispersion patterns and CNC contents on the properties of composite membranes were studied. The analysis of the surface and cross-section morphology of the membranes showed that the dispersion performance of the composite membrane was better in the case that CNC was dissolved in an acetic acid solution and then mixed with chitosan by a homogenizer (Method 2). CNC had a great length-diameter ratio and CNC intensely interacted with CS. The mechanical properties of the composite membrane prepared with Method 2 were better. With a CNC content of 3%, the tensile strength of the composite membrane reached 43.0 MPa, 13.2% higher than that of the CNC-free membrane. The elongation at break was 41.6%, 56.4% higher than that of the CNC-free membrane. Thermogravimetric, contact angle and swelling analysis results showed that the addition of CNC could improve the heat and water resistance of the chitosan membrane. Full article

(This article belongs to the Special Issue Processing and Molding of Polymers)

► Show Figures

Graphical abstract

12 pages, 3206 KiB

Open AccessEditor’s ChoiceArticle

Patterned Polyvinyl Alcohol Hydrogel Dressings with Stem Cells Seeded for Wound Healing

by Tianlin Gao, Menghui Jiang, Xiaoqian Liu, Guoju You, Wenyu Wang, Zhaohui Sun, Aiguo Ma and Jie Chen

Polymers 2019, 11(1), 171; https://doi.org/10.3390/polym11010171 - 18 Jan 2019

Cited by 56 | Viewed by 7335

Abstract

Polyvinyl alcohol (PVA) hydrogel and stem cell therapy have been widely used in wound healing. However, the lack of bioactivity for PVA and security of stem therapy limited their application. In this study, an adipose-derived stem cells (ADSCs)-seeded PVA dressing (ADSCs/PVA) was prepared [...] Read more.

Polyvinyl alcohol (PVA) hydrogel and stem cell therapy have been widely used in wound healing. However, the lack of bioactivity for PVA and security of stem therapy limited their application. In this study, an adipose-derived stem cells (ADSCs)-seeded PVA dressing (ADSCs/PVA) was prepared for wound healing. One side of the PVA dressing was modified with photo-reactive gelatin (Az-Gel) via ultraviolet (UV) irradiation (Az-Gel@PVA), and thus ADSCs could adhere, proliferate on the PVA dressings and keep the other side of the dressings without adhering to the wound. The structure and mechanics of Az-Gel@PVA were determined by scanning electron microscopy (SEM) and material testing instruments. Then, the adhesion and proliferation of ADSCs were observed via cell counts and live-dead staining. Finally, in vitro and in vivo experiments were utilized to confirm the effect of ADSCs/PVA dressing for wound healing. The results showed that Az-Gel was immobilized on the PVA and showed little effect on the mechanical properties of PVA hydrogels. The surface-modified PVA could facilitate ADSCs adhesion and proliferation. Protein released tests indicated that the bioactive factors secreted from ADSCs could penetrated to the wound. Finally, in vitro and in vivo experiments both suggested the ADSCs/PVA could promote the wound healing via secreting bioactive factors from ADSCs. It was speculated that the ADSCs/PVA dressing could not only promote the wound healing, but also provide a new way for the safe application of stem cells, which would be of great potential for skin tissue engineering. Full article

(This article belongs to the Special Issue Functional Polymers for Biomedicine)

► Show Figures

Graphical abstract

9 pages, 2895 KiB

Open AccessEditor’s ChoiceArticle

Orientation and Dispersion Evolution of Carbon Nanotubes in Ultra High Molecular Weight Polyethylene Composites under Extensional-Shear Coupled Flow: A Dissipative Particle Dynamics Study

by Junxia Wang, Changlin Cao, Xiaochuan Chen, Shijie Ren, Yu Chen, Dingshan Yu and Xudong Chen

Polymers 2019, 11(1), 154; https://doi.org/10.3390/polym11010154 - 17 Jan 2019

Cited by 17 | Viewed by 3718

Abstract

The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in [...] Read more.

The property of carbon nanotubes (CNTs)-based composites are significantly dependent on the orientation and dispersion evolution of CNTs in the polymer matrix. In this work, the dissipative particle dynamics (DPD) simulations are employed to discover the orientation and dispersion evolution of CNTs in ultra–high molecular weight polyethylene (UHMWPE) under extensional–shear coupled flow conditions for the first time. In this paper, we investigate the roles of the increasing extensional-shear coupled rate in morphology of CNTs/UHMWPE composites by varying CNTs concentration and observe that the system under consideration lies in the same evolution morphologies. When comparing our results for various morphologies, we notice that the orientation is affected more significantly by changing the extensional-shear coupled rates. A good alignment appears with an increase of extensional-shear coupled rates, which transform it into ordered morphology. In addition, a higher extensional-shear coupled rate does not necessarily contribute to better dispersion even though CNTs concentration varies, as shown by the mean square displacement (MSD) and the relative concentration distribution functions of CNTs in CNTs/UHMWPE composites. Full article

(This article belongs to the Special Issue Polymer-CNT Nanocomposites)

► Show Figures

Graphical abstract

15 pages, 5808 KiB

Open AccessEditor’s ChoiceArticle

Effect of Thermal Ageing on the Impact Damage Resistance and Tolerance of Carbon-Fibre-Reinforced Epoxy Laminates

by Irene García-Moreno, Miguel Ángel Caminero, Gloria Patricia Rodríguez and Juan José López-Cela

Polymers 2019, 11(1), 160; https://doi.org/10.3390/polym11010160 - 17 Jan 2019

Cited by 35 | Viewed by 5507

Abstract

Composite structures are particularly vulnerable to impact, which drastically reduces their residual strength, in particular, at high temperatures. The glass-transition temperature (T_g) of a polymer is a critical factor that can modify the mechanical properties of the material, affecting its [...] Read more.

Composite structures are particularly vulnerable to impact, which drastically reduces their residual strength, in particular, at high temperatures. The glass-transition temperature (T_g) of a polymer is a critical factor that can modify the mechanical properties of the material, affecting its density, hardness and rigidity. In this work, the influence of thermal ageing on the low-velocity impact resistance and tolerance of composites is investigated by means of compression after impact (CAI) tests. Carbon-fibre-reinforced polymer (CFRP) laminates with a T_g of 195 °C were manufactured and subjected to thermal ageing treatments at 190 and 210 °C for 10 and 20 days. Drop-weight impact tests were carried out to determine the impact response of the different composite laminates. Compression after impact tests were performed in a non-standard CAI device in order to obtain the compression residual strength. Ultrasonic C-scanning of impacted samples were examined to assess the failure mechanisms of the different configurations as a function of temperature. It was observed that damage tolerance decreases as temperature increases. Nevertheless, a post-curing process was found at temperatures below the T_g that enhances the adhesion between matrix and fibres and improves the impact resistance. Finally, the results obtained demonstrate that temperature can cause significant changes to the impact behaviour of composites and must be taken to account when designing for structural applications. Full article

(This article belongs to the Collection Assessment of the Ageing and Durability of Polymers)

► Show Figures

Graphical abstract

11 pages, 5212 KiB

Open AccessEditor’s ChoiceArticle

Improving the Performances of Perovskite Solar Cells via Modification of Electron Transport Layer

by Mao Jiang, Qiaoli Niu, Xiao Tang, Heyi Zhang, Haowen Xu, Wentao Huang, Jizhong Yao, Buyi Yan and Ruidong Xia

Polymers 2019, 11(1), 147; https://doi.org/10.3390/polym11010147 - 16 Jan 2019

Cited by 32 | Viewed by 6376

Abstract

The commonly used electron transport material (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) for perovskite solar cells (PSC) with inverted planar structures suffers from properties such as poor film-forming. In this manuscript, we demonstrate a simple method to improve the film-forming properties of PCBM [...] Read more.

The commonly used electron transport material (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) for perovskite solar cells (PSC) with inverted planar structures suffers from properties such as poor film-forming. In this manuscript, we demonstrate a simple method to improve the film-forming properties of PCBM by doping PCBM with poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as the electron transport layer (ETL), which effectively enhances the performance of CH₃NH₃PbI₃ based solar cells. With 5 wt % F8BT in PCBM, the short circuit current (J_SC) and fill factor (FF) of PSC both significantly increased from 17.21 ± 0.15 mA·cm⁻² and 71.1 ± 0.07% to 19.28 ± 0.22 mA·cm⁻² and 74.7 ± 0.21%, respectively, which led to a power conversion efficiency (PCE) improvement from 12.6 ± 0.24% to 15 ± 0.26%. The morphology investigation suggested that doping with F8BT facilitated the formation of a smooth and uniform ETL, which was favorable for the separation of electron-hole pairs, and therefore, an improved performance of PSC. Full article

(This article belongs to the Special Issue Synthesis and Application of Conjugated Polymers)

► Show Figures

Graphical abstract

15 pages, 3272 KiB

Open AccessEditor’s ChoiceArticle

Surface Modification of Aluminum Nitride to Fabricate Thermally Conductive poly(Butylene Succinate) Nanocomposite

by Zelalem Lule and Jooheon Kim

Polymers 2019, 11(1), 148; https://doi.org/10.3390/polym11010148 - 16 Jan 2019

Cited by 52 | Viewed by 5452

Abstract

Biodegradable polymers and their composites are considered promising materials for replacing conventional polymer plastics in various engineering fields. In this study, poly(butylene succinate) (PBS) composites filled with 5% aluminum nitride nanoparticles were successfully fabricated. The aluminum nitride nanoparticles were surface-modified to improve their [...] Read more.

Biodegradable polymers and their composites are considered promising materials for replacing conventional polymer plastics in various engineering fields. In this study, poly(butylene succinate) (PBS) composites filled with 5% aluminum nitride nanoparticles were successfully fabricated. The aluminum nitride nanoparticles were surface-modified to improve their interaction with the PBS matrix. Field-emission scanning electron microscopy revealed that the nanocomposites with surface-modified nanoparticles had better interface interaction and dispersion in the polymer matrix than those with untreated nanoparticles. The PBS/modified AlN nanocomposites exhibited maximal thermal conductivity enhancement, 63.7%, compared to the neat PBS. In addition, other thermomechanical properties of the PBS nanocomposites were investigated in this study. The nanocomposites also showed a superior storage modulus compared to the neat PBS matrix. In this work, a PBS nanocomposite with suitable thermal conductivity that can be used in various electronic fields was fabricated. Full article

(This article belongs to the Special Issue Advanced Engineering Plastics)

► Show Figures

Graphical abstract

46 pages, 9175 KiB

Open AccessEditor’s ChoiceReview

The Applications of Polymers in Solar Cells: A Review

by Wenjing Hou, Yaoming Xiao, Gaoyi Han and Jeng-Yu Lin

Polymers 2019, 11(1), 143; https://doi.org/10.3390/polym11010143 - 15 Jan 2019

Cited by 141 | Viewed by 18000

Abstract

The emerging dye-sensitized solar cells, perovskite solar cells, and organic solar cells have been regarded as promising photovoltaic technologies. The device structures and components of these solar cells are imperative to the device’s efficiency and stability. Polymers can be used to adjust the [...] Read more.

The emerging dye-sensitized solar cells, perovskite solar cells, and organic solar cells have been regarded as promising photovoltaic technologies. The device structures and components of these solar cells are imperative to the device’s efficiency and stability. Polymers can be used to adjust the device components and structures of these solar cells purposefully, due to their diversified properties. In dye-sensitized solar cells, polymers can be used as flexible substrates, pore- and film-forming agents of photoanode films, platinum-free counter electrodes, and the frameworks of quasi-solid-state electrolytes. In perovskite solar cells, polymers can be used as the additives to adjust the nucleation and crystallization processes in perovskite films. The polymers can also be used as hole transfer materials, electron transfer materials, and interface layer to enhance the carrier separation efficiency and reduce the recombination. In organic solar cells, polymers are often used as donor layers, buffer layers, and other polymer-based micro/nanostructures in binary or ternary devices to influence device performances. The current achievements about the applications of polymers in solar cells are reviewed and analyzed. In addition, the benefits of polymers for solar cells, the challenges for practical application, and possible solutions are also assessed. Full article

► Show Figures

Figure 1

18 pages, 5267 KiB

Open AccessEditor’s ChoiceArticle

The Effect of Direct-to-Plant Styrene-Butadiene-Styrene Block Copolymer Components on Bitumen Modification

by Wengang Zhang, Zhirong Jia, Yixia Zhang, Kui Hu, Longting Ding and Fang Wang

Polymers 2019, 11(1), 140; https://doi.org/10.3390/polym11010140 - 15 Jan 2019

Cited by 33 | Viewed by 6821

Abstract

Five types of material, styrene-butadiene-styrene block copolymer (SBS), ethyl-vinyl-acetate (EVA), naphthenic oil, maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) and butylated hydroxytoluene (BHT) were used as the raw ingredients for manufacturing direct-to-plant SBS in this paper. Thirteen kinds of direct-to-plant SBS [...] Read more.

Five types of material, styrene-butadiene-styrene block copolymer (SBS), ethyl-vinyl-acetate (EVA), naphthenic oil, maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) and butylated hydroxytoluene (BHT) were used as the raw ingredients for manufacturing direct-to-plant SBS in this paper. Thirteen kinds of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS were prepared as well as the processes diagrammatic sketch of dispersion and swelling of direct-to-plant SBS modifier in bitumen were discussed. Microscopic images of direct-to-plant SBS modified bitumen with different components were obtained using fluorescence microscopy. The micro-images were analysed and quantified with MATLAB software. The influence of key components on the micro-morphology of direct-to-plant SBS-modified bitumen is discussed, followed with the tests on melting points and the melting indexes of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS. The performances test of bitumen and bituminous mixture modified by these direct-to-plant SBS were also conducted. Results show that, with the ratio improvement of EVA/SBS or naphthenic oil/SBS, the number of the pixel dot number of area (SBS) in microscopic images increased. Enlargement of the pixel dot number of centre line elongate and the structure fineness was observed, indicating that the dispersion and swelling effect of the SBS modifier in bitumen had been improved. Meanwhile, the macro index, such as the melting point and melting index of direct-to-plant SBS, was also improved corresponding to the increase of EVA/SBS ratio or naphthenic oil/SBS ratio. With the addition of EVA or naphthene oil content, penetration and ductility of direct-to-plant SBS modified bitumen received gradual enhancement, but the softening point and viscosity were found out to be decreased. The high-temperature and low-temperature performances of direct-to-plant SBS modified bituminous mixture can be effectively improved by adding EVA or naphthenic oil. By meeting the required performances of direct-to-plant SBS, modified bitumen and bituminous mixture, the component of direct-to-plant SBS is recommended as, SBS:EVA:naphthenic oil:EVA-g-MAH:BHT is 1:0.1–0.5:0.05–0.2:0.03:0.05. For the compatibleness of SBS with different bitumen are different, necessary tests verification is recommended to be carried out prior to usage. Full article

► Show Figures

Graphical abstract

16 pages, 5897 KiB

Open AccessEditor’s ChoiceArticle

β-Cyclodextrin–Hyaluronic Acid Polymer Functionalized Magnetic Graphene Oxide Nanocomposites for Targeted Photo-Chemotherapy of Tumor Cells

by Wenting Liang, Yu Huang, Dongtao Lu, Xuewen Ma, Tao Gong, Xiaodong Cui, Baofeng Yu, Cheng Yang, Chuan Dong and Shaomin Shuang

Polymers 2019, 11(1), 133; https://doi.org/10.3390/polym11010133 - 14 Jan 2019

Cited by 59 | Viewed by 7534

Abstract

A multifunctional targeted drug delivery platform (CDHA–MGO) has been successfully constructed by grafting β-cyclodextrin–hyaluronic acid polymers (CDHA) to Fe₃O₄–graphene oxide (MGO). The obtained CDHA–MGO nanocomposite has good water-dispersibility, easy magnetic separation, high near-infrared (NIR) photothermal heating, and excellent biocompatibility. [...] Read more.

A multifunctional targeted drug delivery platform (CDHA–MGO) has been successfully constructed by grafting β-cyclodextrin–hyaluronic acid polymers (CDHA) to Fe₃O₄–graphene oxide (MGO). The obtained CDHA–MGO nanocomposite has good water-dispersibility, easy magnetic separation, high near-infrared (NIR) photothermal heating, and excellent biocompatibility. The β-cyclodextrin-hyaluronic acid polymers efficaciously enhance the doxorubicin (DOX) loading amount up to 485.43 mg·g⁻¹. Meanwhile, the Fe₃O₄–graphene oxide provides a facile photothermal response mechanism to handle the NIR-triggered release of DOX in weak acidic solvent environments. Significantly, the DOX-loaded nanocomposite (DOX@CDHA–MGO) has displayed CD44 receptor-mediated active targeting recognition and chemo-photothermal synergistic therapy of hepatoma cells. These findings suggest that the as-prepared drug delivery platform would be of valuable potential for cancer-targeted photo-chemotherapy. Full article

(This article belongs to the Special Issue Magnetic Field in Polymer Research)

► Show Figures

Graphical abstract

14 pages, 3271 KiB

Open AccessEditor’s ChoiceArticle

Hyaluronic Acid-Decorated Laponite^® Nanocomposites for Targeted Anticancer Drug Delivery

by Tingting Jiang, Guangxiang Chen, Xiangyang Shi and Rui Guo

Polymers 2019, 11(1), 137; https://doi.org/10.3390/polym11010137 - 14 Jan 2019

Cited by 31 | Viewed by 5609

Abstract

In this study, hyaluronic acid (HA), a natural polysaccharide that can specifically bind to CD44 receptors, was conjugated onto laponite^® (LAP) nanodisks for the encapsulation and specific delivery of the anti-cancer drug doxorubicin (DOX) to CD44-overexpressed cancer cells. The prepared LM-HA could [...] Read more.

In this study, hyaluronic acid (HA), a natural polysaccharide that can specifically bind to CD44 receptors, was conjugated onto laponite^® (LAP) nanodisks for the encapsulation and specific delivery of the anti-cancer drug doxorubicin (DOX) to CD44-overexpressed cancer cells. The prepared LM-HA could encapsulate DOX efficiently and release drug in a continuous manner with pH-responsiveness. In vitro cell viability assay proved that LM-HA had good biocompatibility, and drug-loaded LM-HA/DOX exhibited targeted anti-tumor effects against HeLa cells with CD44 receptors overexpressed. In addition, the flow cytometric detection and confocal laser scanning microscope results confirmed that LM-HA/DOX could be specifically internalized by HeLa cells via CD44-mediated endocytosis. Therefore, the HA-modified LAP nanodisks with high drug loading efficiency, pH-sensitive drug release properties and CD44 targetability might be an efficient nanoplatform for cancer chemotherapy. Full article

(This article belongs to the Special Issue Polymer Clay Nano-composites)

► Show Figures

Graphical abstract

19 pages, 5741 KiB

Open AccessEditor’s ChoiceArticle

Improved Flame-Retardant and Ceramifiable Properties of EVA Composites by Combination of Ammonium Polyphosphate and Aluminum Hydroxide

by Feipeng Lou, Kai Wu, Quan Wang, Zhongyu Qian, Shijuan Li and Weihong Guo

Polymers 2019, 11(1), 125; https://doi.org/10.3390/polym11010125 - 12 Jan 2019

Cited by 43 | Viewed by 5901

Abstract

Ceramifiable flame-retardant ethylene-vinyl acetate (EVA) copolymer composites for wire and cable sheathing materials were prepared through melt compounding with ammonium polyphosphate (APP), aluminum hydroxide (ATH) and fluorophlogopite mica as the addition agents. The effects of ammonium polyphosphate, alumina trihydrate, and APP/ATH hybrid on [...] Read more.

Ceramifiable flame-retardant ethylene-vinyl acetate (EVA) copolymer composites for wire and cable sheathing materials were prepared through melt compounding with ammonium polyphosphate (APP), aluminum hydroxide (ATH) and fluorophlogopite mica as the addition agents. The effects of ammonium polyphosphate, alumina trihydrate, and APP/ATH hybrid on the flame retardant, as well as on the thermal and ceramifiable properties of EVA composites, were investigated. The results demonstrated that the composites with the ratio of APP:ATH = 1:1 displayed the best flame retardancy and the greatest char residues among the various EVA composites. The tensile strength of the composites was 6.8 MPa, and the residue strength sintered at 1000 °C reached 5.2 MPa. The effect of sintering temperature on the ceramifiable properties, microstructures, and crystalline phases of the sintered specimen was subsequently investigated through X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. The XRD and FTIR results demonstrated that the crystal structure of mica was disintegrated, while magnesium orthophosphate (Mg₃(PO₄)₂) was simultaneously produced at an elevated temperature, indicating that the ceramization of EVA composites had occurred. The SEM results demonstrated that a more continuous and compact microstructure was produced with the rise in the sintering temperature. This contributed to the flexural strength improvement of the ceramics. Full article

► Show Figures

Graphical abstract

14 pages, 3830 KiB

Open AccessEditor’s ChoiceArticle

Photoinitiator Free Resins Composed of Plant-Derived Monomers for the Optical µ-3D Printing of Thermosets

by Migle Lebedevaite, Jolita Ostrauskaite, Edvinas Skliutas and Mangirdas Malinauskas

Polymers 2019, 11(1), 116; https://doi.org/10.3390/polym11010116 - 11 Jan 2019

Cited by 76 | Viewed by 11430

Abstract

In this study, acrylated epoxidized soybean oil (AESO) and mixtures of AESO and vanillin dimethacrylate (VDM) or vanillin diacrylate (VDA) were investigated as photosensitive resins for optical 3D printing without any photoinitiator and solvent. The study of photocross-linking kinetics by real-time photorheometry revealed [...] Read more.

In this study, acrylated epoxidized soybean oil (AESO) and mixtures of AESO and vanillin dimethacrylate (VDM) or vanillin diacrylate (VDA) were investigated as photosensitive resins for optical 3D printing without any photoinitiator and solvent. The study of photocross-linking kinetics by real-time photorheometry revealed the higher rate of photocross-linking of pure AESO than that of AESO with VDM or VDA. Through the higher yield of the insoluble fraction, better thermal and mechanical properties were obtained for the pure AESO polymer. Here, for the first time, we validate that pure AESO and mixtures of AESO and VDM can be used for 3D microstructuring by employing direct laser writing lithography technique. The smallest achieved spatial features are 1 µm with a throughput in 6900 voxels per second is obtained. The plant-derived resins were laser polymerized using ultrashort pulses by multiphoton absorption and avalanche induced cross-linking without the usage of any photoinitiator. This advances the light-based additive manufacturing towards the 3D processing of pure cross-linkable renewable materials. Full article

(This article belongs to the Special Issue Thermosets II)

► Show Figures

Graphical abstract

13 pages, 4991 KiB

Open AccessEditor’s ChoiceArticle

Integrating Nano-Cu₂O@ZrP into In Situ Polymerized Polyethylene Terephthalate (PET) Fibers with Enhanced Mechanical Properties and Antibacterial Activities

by Jialiang Zhou, Xiang Fei, Congqi Li, Senlong Yu, Zexu Hu, Hengxue Xiang, Bin Sun and Meifang Zhu

Polymers 2019, 11(1), 113; https://doi.org/10.3390/polym11010113 - 10 Jan 2019

Cited by 24 | Viewed by 4696

Abstract

The approach of in situ polymerization modification has proven to be an effective route for introducing functions for polyester materials. In this work, Cu₂O@ZrP nanosheets with excellent dispersity and high antibacterial activity were integrated into in situ polymerized polyethylene terephthalate (PET) [...] Read more.

The approach of in situ polymerization modification has proven to be an effective route for introducing functions for polyester materials. In this work, Cu₂O@ZrP nanosheets with excellent dispersity and high antibacterial activity were integrated into in situ polymerized polyethylene terephthalate (PET) fibers, revealing an enhanced mechanical performance in comparison with the PET fibers fabricated directly via a traditional melt blending method. Additionally, such an in situ polymerized PET/Cu₂O@ZrP fibers displayed highly enhanced mechanical properties; and great antibacterial activities against multi-types of bacterium, including S. aureus, E. coli and C. albicans. For the as-obtained two types of PET/Cu₂O@ZrP fibers, we have detailed their molecular weight (detailed molecular weight) and dispersibility of nano-Cu₂O@ZrP and fibers crystallinity was investigated by Gel chromatography (GPC), Scanning electron microscope (SEM), and X-ray diffractometer (XRD), respectively. The results showed that the aggregation of the nano-Cu₂O@ZrP in the resultant PET matrix could be effectively prevented during its in situ polymerization process, hence we attribute its highly enhanced mechanical properties to its superior dispersion of nano-Cu₂O@ZrP. Full article

(This article belongs to the Special Issue Polymer Matrix Composites for Advanced Applications)

► Show Figures

Graphical abstract

16 pages, 1996 KiB

Open AccessEditor’s ChoiceArticle

Synthesis and Effect of Structure on Swelling Properties of Hydrogels Based on High Methylated Pectin and Acrylic Polymers

by Grzegorz Kowalski, Karolina Kijowska, Mariusz Witczak, Łukasz Kuterasiński and Marcin Łukasiewicz

Polymers 2019, 11(1), 114; https://doi.org/10.3390/polym11010114 - 10 Jan 2019

Cited by 91 | Viewed by 6560

Abstract

The aim of the research was to develop new pectin-based hydrogels with excellent swelling properties. Superabsorbent hydrogels composed of high methylated pectin and partially neutralized poly(acrylic acid) was obtained by free radical polymerization in aqueous solution in the presence of crosslinking agent—N [...] Read more.

The aim of the research was to develop new pectin-based hydrogels with excellent swelling properties. Superabsorbent hydrogels composed of high methylated pectin and partially neutralized poly(acrylic acid) was obtained by free radical polymerization in aqueous solution in the presence of crosslinking agent—N,N’-methylenebisacrylamide. The effect of crosslinker content and pectin to acrylic acid ratio on the swelling properties of hydrogels was investigated. In addition, the thermodynamic characteristic of hydrogels was obtained by DSC. Furthermore, the structure of pectin-based hydrogels was characterized by FTIR and GPC. It was also proved that poly(acrylic acid) is grafted on pectin particles. The results showed that introduction of small amount of pectin (up to 6.7 wt %) to poly(acrylic acid) hydrogel increase the swelling capacity, while further increasing of pectin ratio cause decrease of swelling. Full article

► Show Figures

Graphical abstract

10 pages, 2551 KiB

Open AccessEditor’s ChoiceArticle

Extrusion Foaming of Lightweight Polystyrene Composite Foams with Controllable Cellular Structure for Sound Absorption Application

by Yanpei Fei, Wei Fang, Mingqiang Zhong, Jiangming Jin, Ping Fan, Jintao Yang, Zhengdong Fei, Lixin Xu and Feng Chen

Polymers 2019, 11(1), 106; https://doi.org/10.3390/polym11010106 - 9 Jan 2019

Cited by 33 | Viewed by 5241

Abstract

Polymer foams are promising for sound absorption applications. In order to process an industrial product, a series of polystyrene (PS) composite foams were prepared by continuous extrusion foaming assisted by supercritical CO₂. Because the cell size and cell density were the [...] Read more.

Polymer foams are promising for sound absorption applications. In order to process an industrial product, a series of polystyrene (PS) composite foams were prepared by continuous extrusion foaming assisted by supercritical CO₂. Because the cell size and cell density were the key to determine the sound absorption coefficient at normal incidence, the bio-resource lignin was employed for the first time to control the cellular structure on basis of hetero-nucleation effect. The sound absorption range of the PS/lignin composite foams was corresponding to the cellular structure and lignin content. As a result, the maximum sound absorption coefficient at normal incidence was higher than 0.90. For a comparison, multiwall carbon nanotube (MWCNT) and micro graphite (mGr) particles were also used as the nucleation agent during the foaming process, respectively, which were more effective on the hetero-nucleation effect. The mechanical property and thermal stability of various foams were measured as well. Lignin showed a fire retardant effect in PS composite foam. Full article

(This article belongs to the Special Issue Polymeric Foams)

► Show Figures

Graphical abstract

19 pages, 4785 KiB

Open AccessEditor’s ChoiceReview

Recent Progress in Thermoelectric Materials Based on Conjugated Polymers

by Chang-Jiang Yao, Hao-Li Zhang and Qichun Zhang

Polymers 2019, 11(1), 107; https://doi.org/10.3390/polym11010107 - 9 Jan 2019

Cited by 185 | Viewed by 11001

Abstract

Organic thermoelectric (TE) materials can directly convert heat to electricity, and they are emerging as new materials for energy harvesting and cooling technologies. The performance of TE materials mainly depends on the properties of materials, including the Seebeck coefficient, electrical conductivity, thermal conductivity, [...] Read more.

Organic thermoelectric (TE) materials can directly convert heat to electricity, and they are emerging as new materials for energy harvesting and cooling technologies. The performance of TE materials mainly depends on the properties of materials, including the Seebeck coefficient, electrical conductivity, thermal conductivity, and thermal stability. Traditional TE materials are mostly based on low-bandgap inorganic compounds, such as bismuth chalcogenide, lead telluride, and tin selenide, while organic materials as promising TE materials are attracting more and more attention because of their intrinsic advantages, including cost-effectiveness, easy processing, low density, low thermal conductivity, and high flexibility. However, to meet the requirements of practical applications, the performance of organic TE materials needs much improvement. A variety of efforts have been made to enhance the performance of organic TE materials, including the modification of molecular structure, and chemical or electrochemical doping. In this review, we summarize recent progress in organic TE materials, and discuss the feasible strategies for enhancing the properties of organic TE materials for future energy-harvesting applications. Full article

► Show Figures

Graphical abstract

15 pages, 4081 KiB

Open AccessEditor’s ChoiceArticle

Dynamically Cross-Linked Tannin as a Reinforcement of Polypropylene and UV Protection Properties

by Jingjing Liao, Nicolas Brosse, Antonio Pizzi and Sandrine Hoppe

Polymers 2019, 11(1), 102; https://doi.org/10.3390/polym11010102 - 9 Jan 2019

Cited by 30 | Viewed by 3986

Abstract

Tannins were used as reinforcing components for polypropylene with anti-UV properties via dynamic curing extrusion. The influence of cross-linked tannins in different weight fraction and their anti-UV capacity on morphological, mechanical, rheological, crystallize and thermal properties were studied. The experimental results indicated that [...] Read more.

Tannins were used as reinforcing components for polypropylene with anti-UV properties via dynamic curing extrusion. The influence of cross-linked tannins in different weight fraction and their anti-UV capacity on morphological, mechanical, rheological, crystallize and thermal properties were studied. The experimental results indicated that the cross-linked tannins improve Young’s modulus, crystallinity, and thermal stability and reinforce the internal network of polypropylene. After UV accelerated weathering, polypropylene had fewer surface cracks, lower carbonyl index, fewer crystallinity decreases and less mechanical properties loss with increasing tannin content. Full article

► Show Figures

Graphical abstract

13 pages, 2048 KiB

Open AccessEditor’s ChoiceArticle

Effect of Matrix and Graphite Filler on Thermal Conductivity of Industrially Feasible Injection Molded Thermoplastic Composites

by Tom Wieme, Lingyan Duan, Nicolas Mys, Ludwig Cardon and Dagmar R. D’hooge

Polymers 2019, 11(1), 87; https://doi.org/10.3390/polym11010087 - 8 Jan 2019

Cited by 33 | Viewed by 4702

Abstract

To understand how the thermal conductivity (TC) of virgin commercial polymers and their composites with low graphite filler amounts can be improved, the effect of material choice, annealing and moisture content is investigated, all with feasible industrial applicability in mind focusing on injection [...] Read more.

To understand how the thermal conductivity (TC) of virgin commercial polymers and their composites with low graphite filler amounts can be improved, the effect of material choice, annealing and moisture content is investigated, all with feasible industrial applicability in mind focusing on injection molding. Comparison of commercial HDPE, PP, PLA, ABS, PS, and PA6 based composites under conditions minimizing the effect of the skin-core layer (measurement at half the sample thickness) allows to deduce that at 20 m% of filler, both the (overall) in- and through-plane TC can be significantly improved. The most promising results are for HDPE and PA6 (through/in-plane TC near 0.7/4.3 W·m⁻¹K⁻¹ for HDPE and 0.47/4.3 W·m⁻¹K⁻¹ for PA6 or an increase of 50/825% and 45/1200% respectively, compared to the virgin polymer). Testing with annealed and nucleated PA6 and PLA samples shows that further increasing the crystallinity has a limited effect. A variation of the average molar mass and moisture content is also almost without impact. Intriguingly, the variation of the measuring depth allows to control the relative importance of the TC of the core and skin layer. An increased measurement depth, hence, a higher core-to-skin ratio measurement specifically indicates a clear increase in the through-plane TC (e.g., factor 2). Therefore, for basic shapes, the removal of the skin layer is recommendable to increase the TC. Full article

(This article belongs to the Special Issue Polymers for Modern and Advanced Engineering Applications)

► Show Figures

Graphical abstract

15 pages, 4833 KiB

Open AccessEditor’s ChoiceArticle

Facile Fabrication of Superhydrophobic Copper- Foam and Electrospinning Polystyrene Fiber for Combinational Oil–Water Separation

by Yu-Ping Zhang, Jing-Hua Yang, Ling-Li Li, Cheng-Xing Cui, Ying Li, Shan-Qin Liu, Xiao-Mao Zhou and Ling-Bo Qu

Polymers 2019, 11(1), 97; https://doi.org/10.3390/polym11010097 - 8 Jan 2019

Cited by 37 | Viewed by 5455

Abstract

Membrane-based metal substrates with special surface wettability have been applied widely for oil/water separation. In this work, a series of copper foams with superhydrophobicity and superoleophilicity were chemically etched using 10 mg mL−1 FeCl3/HCl solution with consequent ultrasonication, followed by the subsequent modification [...] Read more.

Membrane-based metal substrates with special surface wettability have been applied widely for oil/water separation. In this work, a series of copper foams with superhydrophobicity and superoleophilicity were chemically etched using 10 mg mL−1 FeCl3/HCl solution with consequent ultrasonication, followed by the subsequent modification of four sulfhydryl compounds. A water contact angle of 158° and a sliding angle lower than 5° were achieved for the copper foam modified using 10 mM n-octadecanethiol solution in ethanol. In addition, the interaction mechanism was initially investigated, indicating the coordination between copper atoms with vacant orbital and sulfur atoms with lone pair electrons. In addition, the polymeric fibers were electrospun through the dissolution of polystyrene in a good solvent of chlorobenzene, and a nonsolvent of dimethyl sulfoxide. Oil absorption and collection over the water surface were carried out by the miniature boat made out of copper foam, a string bag of as-spun PS fibers with high oil absorption capacity, or the porous boat embedded with the as-spun fibers, respectively. The findings might provide a simple and practical combinational method for the solution of oil spill. Full article

(This article belongs to the Special Issue Superwetting Polymeric Composites)

► Show Figures

Graphical abstract

35 pages, 8537 KiB

Open AccessEditor’s ChoiceReview

Electroluminochromic Materials: From Molecules to Polymers

by Ming Hui Chua, Qiang Zhu, Kwok Wei Shah and Jianwei Xu

Polymers 2019, 11(1), 98; https://doi.org/10.3390/polym11010098 - 8 Jan 2019

Cited by 44 | Viewed by 5944

Abstract

Electroluminochromism is an interesting property found in certain classes of molecules and polymers whose photoluminescence can be modulated through the application of an external electrical bias. Unlike electrochromic materials, electroluminochromic counterparts and their applications are comparatively fewer in quantity and are less established. [...] Read more.

Electroluminochromism is an interesting property found in certain classes of molecules and polymers whose photoluminescence can be modulated through the application of an external electrical bias. Unlike electrochromic materials, electroluminochromic counterparts and their applications are comparatively fewer in quantity and are less established. Nonetheless, there prevails an increasing interest in this class of electro-active materials due to their potential applications in optoelectronics, such as smart-displays, and chemical and biological sensing. This review seeks to showcase the different classes of electroluminochromic materials with focus on (i) organic molecules, (ii) transition metal complexes, and (iii) organic polymers. The mechanisms and electroluminochromic performance of these classes of materials are summarized. This review should allow scientists to have a better and deeper understanding of materials design strategies and, more importantly, structure-property relationships and, thus, develops electroluminochromic materials with desired performance in the future. Full article

(This article belongs to the Special Issue Electrochromic Polymers)

► Show Figures

Graphical abstract

14 pages, 5036 KiB

Open AccessEditor’s ChoiceArticle

Dissolved Gases Forecasting Based on Wavelet Least Squares Support Vector Regression and Imperialist Competition Algorithm for Assessing Incipient Faults of Transformer Polymer Insulation

by Jiefeng Liu, Hanbo Zheng, Yiyi Zhang, Xin Li, Jiake Fang, Yang Liu, Changyi Liao, Yuquan Li and Junhui Zhao

Polymers 2019, 11(1), 85; https://doi.org/10.3390/polym11010085 - 8 Jan 2019

Cited by 25 | Viewed by 3453

Abstract

A solution for forecasting the dissolved gases in oil-immersed transformers has been proposed based on the wavelet technique and least squares support vector machine. In order to optimize the hyper-parameters of the constructed wavelet LS-SVM regression, the imperialist competition algorithm was then applied. [...] Read more.

A solution for forecasting the dissolved gases in oil-immersed transformers has been proposed based on the wavelet technique and least squares support vector machine. In order to optimize the hyper-parameters of the constructed wavelet LS-SVM regression, the imperialist competition algorithm was then applied. In this study, the assessment of prediction performance is based on the squared correlation coefficient and mean absolute percentage error methods. According to the proposed method, this novel procedure was applied to a simulated case and the experimental results show that the dissolved gas contents could be accurately predicted using this method. Besides, the proposed approach was compared to other prediction methods such as the back propagation neural network, the radial basis function neural network, and generalized regression neural network. By comparison, it was inferred that this method is more effective than previous forecasting methods. Full article

(This article belongs to the Special Issue Polymers for Energy Applications)

► Show Figures

Figure 1

18 pages, 5093 KiB

Open AccessEditor’s ChoiceReview

Protein–Polyelectrolyte Interaction: Thermodynamic Analysis Based on the Titration Method ^†

by Xiaohan Wang, Kai Zheng, Yi Si, Xuhong Guo and Yisheng Xu

Polymers 2019, 11(1), 82; https://doi.org/10.3390/polym11010082 - 7 Jan 2019

Cited by 26 | Viewed by 6369

Abstract

This review discussed the mechanisms including theories and binding stages concerning the protein–polyelectrolyte (PE) interaction, as well as the applications for both complexation and coacervation states of protein–PE pairs. In particular, this review focused on the applications of titration techniques, that is, turbidimetric [...] Read more.

This review discussed the mechanisms including theories and binding stages concerning the protein–polyelectrolyte (PE) interaction, as well as the applications for both complexation and coacervation states of protein–PE pairs. In particular, this review focused on the applications of titration techniques, that is, turbidimetric titration and isothermal titration calorimetry (ITC), in understanding the protein–PE binding process. To be specific, by providing thermodynamic information such as pH_c, pH_φ, binding constant, entropy, and enthalpy change, titration techniques could shed light on the binding affinity, binding stoichiometry, and driving force of the protein–PE interaction, which significantly guide the applications by utilization of these interactions. Recent reports concerning interactions between proteins and different types of polyelectrolytes, that is, linear polyelectrolytes and polyelectrolyte modified nanoparticles, are summarized with their binding differences systematically discussed and compared based on the two major titration techniques. We believe this short review could provide valuable insight in the understanding of the structure–property relationship and the design of applied biomedical PE-based systems with optimal performance. Full article

(This article belongs to the Special Issue Polyelectrolytes and Polyelectrolyte Complexes-in Memory of Prof. Paul Dubin)

► Show Figures

Figure 1

15 pages, 5846 KiB

Open AccessEditor’s ChoiceArticle

Polyelectrolyte Complexation of Oligonucleotides by Charged Hydrophobic—Neutral Hydrophilic Block Copolymers

by Alexander E. Marras, Jeffrey R. Vieregg, Jeffrey M. Ting, Jack D. Rubien and Matthew V. Tirrell

Polymers 2019, 11(1), 83; https://doi.org/10.3390/polym11010083 - 7 Jan 2019

Cited by 39 | Viewed by 8710

Abstract

Polyelectrolyte complex micelles (PCMs, core-shell nanoparticles formed by complexation of a polyelectrolyte with a polyelectrolyte-hydrophilic neutral block copolymer) offer a solution to the critical problem of delivering therapeutic nucleic acids, Despite this, few systematic studies have been conducted on how parameters such as [...] Read more.

Polyelectrolyte complex micelles (PCMs, core-shell nanoparticles formed by complexation of a polyelectrolyte with a polyelectrolyte-hydrophilic neutral block copolymer) offer a solution to the critical problem of delivering therapeutic nucleic acids, Despite this, few systematic studies have been conducted on how parameters such as polycation charge density, hydrophobicity, and choice of charged group influence PCM properties, despite evidence that these strongly influence the complexation behavior of polyelectrolyte homopolymers. In this article, we report a comparison of oligonucleotide PCMs and polyelectrolyte complexes formed by poly(lysine) and poly((vinylbenzyl) trimethylammonium) (PVBTMA), a styrenic polycation with comparatively higher charge density, increased hydrophobicity, and a permanent positive charge. All of these differences have been individually suggested to provide increased complex stability, but we find that PVBTMA in fact complexes oligonucleotides more weakly than does poly(lysine), as measured by stability versus added salt. Using small angle X-ray scattering and electron microscopy, we find that PCMs formed from both cationic blocks exhibit very similar structure-property relationships, with PCM radius determined by the cationic block size and shape controlled by the hybridization state of the oligonucleotides. These observations narrow the design space for optimizing therapeutic PCMs and provide new insights into the rich polymer physics of polyelectrolyte self-assembly. Full article

(This article belongs to the Special Issue Polyelectrolytes and Polyelectrolyte Complexes-in Memory of Prof. Paul Dubin)

► Show Figures

Graphical abstract

7 pages, 626 KiB

Open AccessEditor’s ChoiceArticle

Composition of Plastic Fractions in Waste Streams: Toward More Efficient Recycling and Utilization

by Ville Lahtela, Marko Hyvärinen and Timo Kärki

Polymers 2019, 11(1), 69; https://doi.org/10.3390/polym11010069 - 5 Jan 2019

Cited by 44 | Viewed by 10920

Abstract

Reuse of materials is a significant global goal that contributes to sustainable development. Polymer-specific plastic identification from the waste stream is examined in this study to achieve environmentally optimistic reuse of plastic material in secondary applications. Two diverse waste streams, 86.11 kg of [...] Read more.

Reuse of materials is a significant global goal that contributes to sustainable development. Polymer-specific plastic identification from the waste stream is examined in this study to achieve environmentally optimistic reuse of plastic material in secondary applications. Two diverse waste streams, 86.11 kg of construction and demolition waste (CDW) plastic and 57.74 kg of mechanically sorted plastic, were analyzed by using a handheld tool whose identification technology was based on the near-infrared spectrum. The study indicates a significant effect of human and single fraction on manual separation. The polymer composition in the plastic waste stream varied depending on the source, but the most common plastic grades, polypropylene (PP) and polyethylene (PE), were represented in every waste stream. The waste stream also included unidentified and unfavorable wastes, which indicates that identification of the plastic fractions is needed and more studies should be done in this field in the future. Full article

► Show Figures

Graphical abstract

13 pages, 3167 KiB

Open AccessEditor’s ChoiceArticle

Flame Inhibition and Charring Effect of Aromatic Polyimide and Aluminum Diethylphosphinate in Polyamide 6

by Haisheng Feng, Yong Qiu, Lijun Qian, Yajun Chen, Bo Xu and Fei Xin

Polymers 2019, 11(1), 74; https://doi.org/10.3390/polym11010074 - 5 Jan 2019

Cited by 24 | Viewed by 4697

Abstract

An aromatic macromolecular polyimide (API) was synthesized and characterized, and used as a synergistic charring flame retardant in glass fiber reinforced polyamide 6 (GF/PA6). API and aluminum diethylphosphinate (ADP) exhibited better flame inhibition behavior and synergistic charring flame retardant behavior compared with ADP [...] Read more.

An aromatic macromolecular polyimide (API) was synthesized and characterized, and used as a synergistic charring flame retardant in glass fiber reinforced polyamide 6 (GF/PA6). API and aluminum diethylphosphinate (ADP) exhibited better flame inhibition behavior and synergistic charring flame retardant behavior compared with ADP alone. The 5%API/7%ADP/GF/PA6 sample achieved the lower peak value of the heat release rate (pk-HRR) at 497 kW/m² and produced higher residue yields of 36.1 wt.%, verifying that API and ADP have an outstanding synergistic effect on the barrier effect. The API/ADP system facilitated the formation of a carbonaceous, phosphorus and aluminum-containing compact char layer with increased barrier effect. FTIR spectra of the residue and real-time TGA-FTIR analysis on the evolved gases from PA6 composites revealed that API interacted with ADP/PA6 and locked in more P–O–C and P–O–Ar content, which is the main mechanism for improving flame inhibition and charring ability. In addition, the API/ADP system improved the mechanical properties and corrosion resistance of GF/PA6 composites compared to ADP alone. Full article

(This article belongs to the Collection Sustainable Polymeric Materials from Renewable Resources)

► Show Figures

Graphical abstract

14 pages, 6166 KiB

Open AccessEditor’s ChoiceArticle

Multi-Material Additive Manufacturing of Sustainable Innovative Materials and Structures

by Rupinder Singh, Ranvijay Kumar, Ilenia Farina, Francesco Colangelo, Luciano Feo and Fernando Fraternali

Polymers 2019, 11(1), 62; https://doi.org/10.3390/polym11010062 - 4 Jan 2019

Cited by 126 | Viewed by 10071

Abstract

This paper highlights the multi-material additive manufacturing (AM) route for manufacturing of innovative materials and structures. Three different recycled thermoplastics, namely acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and high impact polystyrene (HIPS) (with different Young’s modulus, glass transition temperature, rheological properties), have [...] Read more.

This paper highlights the multi-material additive manufacturing (AM) route for manufacturing of innovative materials and structures. Three different recycled thermoplastics, namely acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and high impact polystyrene (HIPS) (with different Young’s modulus, glass transition temperature, rheological properties), have been selected (as a case study) for multi-material AM. The functional prototypes have been printed on fused deposition modelling (FDM) setup as tensile specimens (as per ASTM D638 type-IV standard) with different combinations of top, middle, and bottom layers (of ABS/PLA/HIPS), at different printing speed and infill percentage density. The specimens were subjected to thermal (glass transition temperature and heat capacity) and mechanical testing (peak load, peak strength, peak elongation, percentage elongation at peak, and Young’s modulus) to ascertain their suitability in load-bearing structures, and the fabrication of functional prototypes of mechanical meta-materials. The results have been supported by photomicrographs to observe the microstructure of the analyzed multi-materials. Full article

(This article belongs to the Special Issue Recycling of Polymers and Multiphase Polymer-Based Systems)

► Show Figures

Graphical abstract

19 pages, 3880 KiB

Open AccessEditor’s ChoiceArticle

Poly(lactic acid)/Cellulose Films Produced from Composite Spheres Prepared by Emulsion-Solvent Evaporation Method

by Sónia Sousa, Ana Costa, Abílio Silva and Rogério Simões

Polymers 2019, 11(1), 66; https://doi.org/10.3390/polym11010066 - 4 Jan 2019

Cited by 38 | Viewed by 6916

Abstract

The compound of poly(lactic acid) (PLA) and cellulose was made by the emulsion-solvent evaporation technique in order to obtain spheres which are then compression molded to produce a biocomposite film. The effect of the dispersant (poly(vinyl alcohol)—PVA)/PLA ratio on the spheres yield was [...] Read more.

The compound of poly(lactic acid) (PLA) and cellulose was made by the emulsion-solvent evaporation technique in order to obtain spheres which are then compression molded to produce a biocomposite film. The effect of the dispersant (poly(vinyl alcohol)—PVA)/PLA ratio on the spheres yield was studied. Moreover, to evaluate the effect of cellulose particle size and surface chemistry on the process yield, unbleached eucalypt kraft pulp and microcrystalline cellulose (MCC), both unmodified and physically or chemically modified were used. PLA/cellulose spheres were characterized regarding its physical properties. It was found that the spheres yield is essentially determined by the PVA/PLA ratio and the percentage of cellulose incorporation is greatly affected by the surface chemistry of cellulose. Regarding the films, DSC runs showed a significant effect of the cellulose type incorporated into PLA matrix on the cold crystallization temperature and on the degree of crystallinity of the biocomposite films. The measurement of tensile properties of the biocomposite films revealed that the strength, elongation at break and toughness (tensile energy absorption at break) of the films incorporating unmodified and chemically modified MCC were substantially improved. Full article

(This article belongs to the Special Issue Bio-Based Polymers for Engineered Green Materials)

► Show Figures

Graphical abstract

20 pages, 6219 KiB

Open AccessEditor’s ChoiceArticle

The Effect of the Surface Area of Carbon Black Grades on HNBR in Harsh Environments

by Winoj Balasooriya, Bernd Schrittesser, Gerald Pinter, Thomas Schwarz and Lucia Conzatti

Polymers 2019, 11(1), 61; https://doi.org/10.3390/polym11010061 - 4 Jan 2019

Cited by 29 | Viewed by 6483

Abstract

Concerning the still rising demand for oil and gas products, the development of new reliable materials to guarantee the facility safety at extreme operating conditions is an utmost necessity. The present study mainly deals with the influence of different carbon black (CB) filled [...] Read more.

Concerning the still rising demand for oil and gas products, the development of new reliable materials to guarantee the facility safety at extreme operating conditions is an utmost necessity. The present study mainly deals with the influence of different carbon black (CB) filled hydrogenated nitrile butadiene rubber (HNBR), which is a material usually used in sealing applications, on the rapid gas decompression (RGD) resistance in harsh environments. Therefore, RGD component level tests were conducted in an autoclave. The supporting mechanical and dynamic mechanical property analysis, the microscopic level investigations on the material and failure analysis were conducted and are discussed in this work. Under the tested conditions, the samples filled with smaller CB primary particles showed a slightly lower volume increase during the compression and decompression phases; however, they steered to a significantly lower resistance to RGD. Transmission electron micrographs revealed that the samples filled with smaller CB particles formed larger structures as well as densified filler networks including larger agglomerates and as a consequence a decrease effective matrix component around the CB particles. Apparently, at higher loading conditions, which already deliver a certain level of mechanical stresses and strains, the densified filler network, and especially a lower amount of effective matrix material composition, adversely affect the RGD resistance. SEM-based fracture analysis did not identify any influence of the CB grades tested on the crack initiation site; however, it revealed that the cracks initiated from existing voids, hard particles, or low strength matrix sites and propagated to the outer surface. Full article

► Show Figures

Graphical abstract

17 pages, 2491 KiB

Open AccessEditor’s ChoiceArticle

Deterioration in the Physico-Mechanical and Thermal Properties of Biopolymers Due to Reprocessing

by Jamileh Shojaeiarani, Dilpreet S. Bajwa, Chad Rehovsky, Sreekala G. Bajwa and Ghazal Vahidi

Polymers 2019, 11(1), 58; https://doi.org/10.3390/polym11010058 - 2 Jan 2019

Cited by 48 | Viewed by 6736

Abstract

Biopolymers are an emerging class of materials being widely pursued due to their ability to degrade in short periods of time. Understanding and evaluating the recyclability of biopolymers is paramount for their sustainable and efficient use in a cost-effective manner. Recycling has proven [...] Read more.

Biopolymers are an emerging class of materials being widely pursued due to their ability to degrade in short periods of time. Understanding and evaluating the recyclability of biopolymers is paramount for their sustainable and efficient use in a cost-effective manner. Recycling has proven to be an important solution, to control environmental and waste management issues. This paper presents the first recycling assessment of Solanyl, Bioflex, polylactic acid (PLA) and PHBV using a melt extrusion process. All biopolymers were subjected to five reprocessing cycles. The thermal and mechanical properties of the biopolymers were investigated by GPC, TGA, DSC, mechanical test, and DMA. The molecular weights of Bioflex and Solanyl showed no susceptible effect of the recycling process, however, a significant reduction was observed in the molecular weight of PLA and PHBV. The inherent thermo-mechanical degradation in PHBV and PLA resulted in 20% and 7% reduction in storage modulus, respectively while minimal reduction was observed in the storage modulus of Bioflex and Solanyl. As expected from the Florry-Fox equation, recycled PLA with a high reduction in molecular weight (78%) experienced 9% reduction in glass transition temperature. Bioflex and Solanyl showed 5% and 2% reduction in molecular weight and experienced only 2% reduction in glass transition temperature. These findings highlight the recyclability potential of Bioflex and Solanyl over PLA and PHBV. Full article

(This article belongs to the Special Issue Bio-Based Polymers for Engineered Green Materials)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Editor’s Choice Articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI