Polymers

18 pages, 3916 KiB

Open AccessArticle

Polymer Having Dicationic Structure in Dumbbell Shape for Forward Osmosis Process

by Taehyung Kim, Changha Ju, Chanhyuk Park and Hyo Kang

Polymers 2019, 11(3), 571; https://doi.org/10.3390/polym11030571 - 26 Mar 2019

Cited by 7 | Viewed by 3953

The thermal-responsive polymers, poly(alkane-1,#-diylbis(tri-n-butylphosphonium) 4-vinylbenzenesulfonate) (PSSBP#, # = 8, 6, and 4), where # is the number of carbon atoms in the central bridge structure of the dicationic phosphonium moiety, were synthesized to examine their potential application as draw solutes in [...] Read more.

The thermal-responsive polymers, poly(alkane-1,#-diylbis(tri-n-butylphosphonium) 4-vinylbenzenesulfonate) (PSSBP#, # = 8, 6, and 4), where # is the number of carbon atoms in the central bridge structure of the dicationic phosphonium moiety, were synthesized to examine their potential application as draw solutes in forward osmosis (FO). The polymers exhibited low critical solution temperature (LCST) characteristics in aqueous solutions, which is essential for recovering a draw solute from pure water. The LCSTs of the 20 wt% aqueous solutions of PSSBP8, PSSBP6, and PSSBP4 were confirmed to be approximately 30, 38, and 26 °C, respectively, which is advantageous in terms of energy requirements for the recovering draw solute. When the concentration of the PSSBP4 draw solution was 20 wt%, water flux and reverse solute flux were approximately 1.61 LMH and 0.91 gMH, respectively, in the active layer facing the draw solution (AL-DS) system when the feed solution was distilled water. The PSSBP# thermal-responsive draw solute has considerable potential for use as a next-generation draw solute because of its excellent osmotic performance and efficient recovery. Therefore, this study provides inspiration for novel ideas regarding structural transformations of polymers and their applicability as draw solutes. Full article

► Show Figures

Graphical abstract

19 pages, 3715 KiB

Open AccessArticle

Exploring Matrix Effects on Binding Properties and Characterization of Cotinine Molecularly Imprinted Polymer on Paper-Based Scaffold

by Nutcha Larpant, Yaneenart Suwanwong, Somchai Boonpangrak and Wanida Laiwattanapaisal

Polymers 2019, 11(3), 570; https://doi.org/10.3390/polym11030570 - 26 Mar 2019

Cited by 9 | Viewed by 4380

Abstract

Commercially available sorbent materials for solid-phase extraction are widely used in analytical laboratories. However, non-selective binding is a major obstacle for sample analysis. To overcome this problem, molecularly imprinted polymers (MIPs) were used as selective adsorbent materials prior to determining target analysts. In [...] Read more.

Commercially available sorbent materials for solid-phase extraction are widely used in analytical laboratories. However, non-selective binding is a major obstacle for sample analysis. To overcome this problem, molecularly imprinted polymers (MIPs) were used as selective adsorbent materials prior to determining target analysts. In this study, the use of non-covalent molecularly imprinted polymers (MIPs) for cotinine adsorption on a paper-based scaffold was studied. Fiberglass paper was used as a paper scaffold for cotinine-selective MIP adsorption with the use of 0.5% agarose gel. The effects of salt, pH, sample matrix, and solvent on the cotinine adsorption and extraction process were investigated. Under optimal conditions, the adsorption isotherm of synthesized MIPs increased to 125.41 µg/g, whereas the maximum adsorption isotherm of non-imprinted polymers (NIPs) was stable at 42.86 µg/g. The ability of the MIP paper scaffold to absorb cotinine in water medium was approximately 1.8–2.8-fold higher than that of the NIP scaffold. From Scatchard analysis, two dissociation constants of MIPs were calculated to be 2.56 and 27.03 µM. Nicotine, myosmine, and N-nitrosonornicotine were used for selectivity testing, and the calculated selectivity factor of cotinine to nicotine, myosmine, and N-nitrosonornicotine was 1.56, 2.69, and 2.05, respectively. Overall, the MIP paper scaffold is promising for simple onsite sampling of cotinine and can be used to assess tobacco smoke exposure. Full article

► Show Figures

Graphical abstract

10 pages, 3304 KiB

Open AccessEditor’s ChoiceCommunication

Formulation and Characterization of a SIS-Based Photocrosslinkable Bioink

by Julian A. Serna, Sergio Leonardo Florez, Vivian A. Talero, Juan C. Briceño, Carolina Muñoz-Camargo and Juan C. Cruz

Polymers 2019, 11(3), 569; https://doi.org/10.3390/polym11030569 - 26 Mar 2019

Cited by 29 | Viewed by 6116

Abstract

Decellularized extracellular matrices (dECMs) represent a promising alternative as a source of materials to develop scaffolds that closely mimic the native environment of cells. As a result, dECMs have attracted significant attention for their applications in regenerative medicine and tissue engineering. One such [...] Read more.

Decellularized extracellular matrices (dECMs) represent a promising alternative as a source of materials to develop scaffolds that closely mimic the native environment of cells. As a result, dECMs have attracted significant attention for their applications in regenerative medicine and tissue engineering. One such application is 3D bioprinting, in which dECMs can be used to prepare bioinks with the biomimicry attributes required for regeneration purposes. Formulating bioinks is, however, challenging, due to difficulties in assuring that the printed materials match the mechanical properties of the tissue which is to be regenerated. To tackle this issue, a number of strategies have been devised, including crosslinking methods, the addition of synthetic materials as excipients, and the use of synthetic matrices for casting. We are particularly interested in extrusion-based 3D bioprinting, mainly due to the ease of rapidly conducting tests for adjusting operating conditions such that the required rheological and mechanical properties are met when using it. Here, we propose a novel bioink that consists of an acid-based precipitation of a small intestinal submucosa (SIS) dECM. The formulated bioink also relies on photocrosslinking reactions to attempt to control gelation and ultimately the mechanical properties of the extruded material. Photoinitiation was explored with the aid of varying concentrations of riboflavin (RF). Manual extrusion and rheological flow tests confirmed the printability and shear-thinning behavior of all formulations. Photocrosslinking reactions, however, failed to promote a substantial increase in gelation, which was attributed to considerable entanglement of undigested collagen molecules. As a result, pendant amine groups thought to be involved in the photo-mediated reactions remain largely inaccessible. In silico computational fluid dynamics (CFD) simulations were implemented to determine shear stress values on the bioink along the exit of the printing nozzle. Moreover, we calculated a stability parameter as a means to estimate changes in the bioink stability during the extrusion process. Future studies should be directed toward assessing the role of temperature-induced gelation in the rheological properties of the bioink and the development of strategies to improve the efficiency of photocrosslinking processes. Full article

► Show Figures

Graphical abstract

14 pages, 2628 KiB

Open AccessEditor’s ChoiceArticle

Core-Shell Structured HMX@Polydopamine Energetic Microspheres: Synergistically Enhanced Mechanical, Thermal, and Safety Performances

by Congmei Lin, Feiyan Gong, Zhijian Yang, Xu Zhao, Yubin Li, Chengcheng Zeng, Jiang Li and Shaoyun Guo

Polymers 2019, 11(3), 568; https://doi.org/10.3390/polym11030568 - 26 Mar 2019

Cited by 66 | Viewed by 5877

Abstract

The solid–solid phase transition, poor mechanical properties, and high sensitivity has impeded further practical applications of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based polymer bonded explosives (PBXs). To address these issues together, a facile and effective route was employed to achieve a coating of polydopamine (PDA) on [...] Read more.

The solid–solid phase transition, poor mechanical properties, and high sensitivity has impeded further practical applications of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) based polymer bonded explosives (PBXs). To address these issues together, a facile and effective route was employed to achieve a coating of polydopamine (PDA) on the surface of explosive crystals via in situ polymerization of dopamine. Additionally, PBXs based on HMX@PDA microcapsules were prepared with a fluoropolymer as polymer binder. Improved storage modulus, static mechanical strength and toughness, and creep resistance has been achieved in as-prepared PDA modified PBXs. The β-δ phase transition temperature of as-obtained PBXs based on conventional HMX (C-HMX)@PDA was improved by 16.3 °C. The friction sensitivity of the C-HMX based PBXs showed a dramatic drop after the PDA coating. A favorable balance proposed in this paper among thermal stability, mechanical properties, and sensitivity was achieved for C-HMX based PBXs with the incorporation of PDA. Full article

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

► Show Figures

Figure 1

9 pages, 1206 KiB

Open AccessArticle

Comparison of Membrane Inlet and Capillary Introduction Miniature Mass Spectrometry for Liquid Analysis

by Wenyan Shi, Xinqiong Lu, Jinbo Zhang, Jianhong Zhao, Lili Yang, Quan Yu and Xiaohao Wang

Polymers 2019, 11(3), 567; https://doi.org/10.3390/polym11030567 - 26 Mar 2019

Cited by 11 | Viewed by 4430

Abstract

Membrane inlet mass spectrometry (MIMS) is commonly used for detecting the components in liquid samples. When a liquid sample flows through a membrane, certain analytes will permeate into the vacuum chamber of a mass spectrometer from the solution. The properties of the membrane [...] Read more.

Membrane inlet mass spectrometry (MIMS) is commonly used for detecting the components in liquid samples. When a liquid sample flows through a membrane, certain analytes will permeate into the vacuum chamber of a mass spectrometer from the solution. The properties of the membrane directly determine the substances that can be detected by MIMS. A capillary introduction (CI) method we previously proposed can also be used to analyze gas and volatile organic compounds (VOCs) dissolved in liquids. When CI analysis is carried out, the sample is drawn into the mass spectrometer with no species discrimination. The performance of these two injection methods was compared in this study, and similar response time and limit of detection (LOD) can be acquired. Specifically, MIMS can provide better detection sensitivity for most inorganic gases and volatile organic compounds. In contrast, capillary introduction shows wider compatibility on analyte types and quantitative range, and it requires less sample consumption. As the two injection methods have comparable characteristics and can be coupled with a miniature mass spectrometer, factors such as cost, pollution, device size, and sample consumption should be comprehensively considered when choosing a satisfactory injection method in practical applications. Full article

(This article belongs to the Special Issue Polymer for Separation)

► Show Figures

Figure 1

10 pages, 2358 KiB

Open AccessArticle

Impact of Chemical Post-Processing in Fused Deposition Modelling (FDM) on Polylactic Acid (PLA) Surface Quality and Structure

by Ana P. Valerga, Moises Batista, Severo R. Fernandez-Vidal and Antonio J. Gamez

Polymers 2019, 11(3), 566; https://doi.org/10.3390/polym11030566 - 26 Mar 2019

Cited by 60 | Viewed by 5303

Abstract

The application of techniques to improve the surface finish of pieces obtained by fused deposition modelling, as well as other functional aspects, is of great interest nowadays. Polylactic acid, a biodegradable material, has been considered a possible substitute for petroleum-based polymers. In this [...] Read more.

The application of techniques to improve the surface finish of pieces obtained by fused deposition modelling, as well as other functional aspects, is of great interest nowadays. Polylactic acid, a biodegradable material, has been considered a possible substitute for petroleum-based polymers. In this work, different chemical post-processing methods are applied to polylactic acid pieces obtained by fused deposition modelling and some characteristics are studied. Structural, thermal, and crystallinity property changes are analyzed according to the treatments applied. This can prevent degradation, eliminate the glass transition phase of the material, and thereby increase the thermal resistance by about 50 °C. An improvement in the roughness of the pieces of up to 97% was also found. Full article

(This article belongs to the Special Issue Connecting the Fields of Polymer Reaction Engineering and Processing)

► Show Figures

Figure 1

20 pages, 4260 KiB

Open AccessArticle

Synergistic Mechanisms Underlie the Peroxide and Coagent Improvement of Natural-Rubber-Toughened Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Mechanical Performance

by Xiaoying Zhao, Katrina Cornish and Yael Vodovotz

Polymers 2019, 11(3), 565; https://doi.org/10.3390/polym11030565 - 26 Mar 2019

Cited by 32 | Viewed by 11742

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bio-based and biodegradable thermoplastic with restricted industrial applications due to its brittleness and poor processability. Natural rubber (NR) has been used as a toughening agent, but further physical improvements are desired. In this study, rubber toughening efficiency was [...] Read more.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) is a promising bio-based and biodegradable thermoplastic with restricted industrial applications due to its brittleness and poor processability. Natural rubber (NR) has been used as a toughening agent, but further physical improvements are desired. In this study, rubber toughening efficiency was significantly improved through the synergistic use of a trifunctional acrylic coagent and an organic peroxide during reactive extrusion of PHBV and NR. The rheological, crystallization, thermal, morphological, and mechanical properties of PHBV/NR blends with 15% rubber loading were characterized. The peroxide and coagent synergistically crosslinked the rubber phase and grafted PHBV onto rubber backbones, leading to enhanced rubber modulus and cohesive strength as well as improved PHBV–rubber compatibility and blend homogeneity. Simultaneously, the peroxide–coagent treatment decreased PHBV crystallinity and crystal size and depressed peroxy-radical-caused PHBV degradation. The new PHBV/NR blends had a broader processing window, 75% better toughness (based on the notched impact strength data), and 100% better ductility (based on the tensile elongation data) than pristine PHBV. This new rubber-toughened PHBV material has balanced mechanical performance comparable to that of conventional thermoplastics and is suitable for a wide range of plastic applications. Full article

(This article belongs to the Special Issue Recent Advances in Bioplastics)

► Show Figures

Figure 1

12 pages, 5166 KiB

Open AccessArticle

Oxidative Depolymerization of Cellulolytic Enzyme Lignin over Silicotungvanadium Polyoxometalates

by Wenbiao Xu, Xiangyu Li and Junyou Shi

Polymers 2019, 11(3), 564; https://doi.org/10.3390/polym11030564 - 26 Mar 2019

Cited by 14 | Viewed by 5010

Abstract

The aim of this study was to explore the catalytic performance of the oxidative depolymerization of enzymatic hydrolysis lignin from cellulosic ethanol fermentation residue by different vanadium substituted Keggin-type polyoxometalates (K₅[SiVW₁₁O₄₀], K₆[SiV₂W₁₀ [...] Read more.

The aim of this study was to explore the catalytic performance of the oxidative depolymerization of enzymatic hydrolysis lignin from cellulosic ethanol fermentation residue by different vanadium substituted Keggin-type polyoxometalates (K₅[SiVW₁₁O₄₀], K₆[SiV₂W₁₀O₄₀], and K₆H[SiV₃W₉O₄₀]). Depolymerized products were analyzed by gel permeation chromatography (GPC), gas chromatography–mass spectrometer (GC/MS), and two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D HSQC NMR) analysis. All catalysts showed an effective catalytic activity. The best result, concerning the lignin conversion and lignin oil production, was obtained by K₆[SiV₂W₁₀O₄₀], and the highest yield of oxidative depolymerization products of 53 wt % was achieved and the main products were monomer aromatic compounds. The HSQC demonstrated that the catalysts were very effective in breaking the β-O-4 structure, the dominant linkage in lignin, and the GPC analysis demonstrated that the molecular of lignin was declined significantly. These results demonstrate the vanadium substituted silicotungstic polyoxometalates were of highly active and stable catalysts for lignin conversion, and this strategy has the potential to be applicable for production of value-added chemicals from biorefinery lignin. Full article

(This article belongs to the Special Issue Properties, Applications and Perspectives of Lignin)

► Show Figures

Graphical abstract

7 pages, 1394 KiB

Open AccessArticle

A Quinacridone-Diphenylquinoxaline-Based Copolymer for Organic Field-Effect Transistors

by Yong Jin Jeong, Jeong Hyun Oh, Ho Jun Song and Tae Kyu An

Polymers 2019, 11(3), 563; https://doi.org/10.3390/polym11030563 - 26 Mar 2019

Cited by 5 | Viewed by 3404

Abstract

In this work, we characterized poly(quinacridone-diphenylquinoxaline) (PQCTQx). PQCTQx was synthesized by a Suzuki coupling reaction and the synthesized PQCTQx was used as a polymeric semiconducting material in organic field-effect transistors (OFETs) to research the potential of using quinacridone derivatives. The measured field-effect mobility [...] Read more.

In this work, we characterized poly(quinacridone-diphenylquinoxaline) (PQCTQx). PQCTQx was synthesized by a Suzuki coupling reaction and the synthesized PQCTQx was used as a polymeric semiconducting material in organic field-effect transistors (OFETs) to research the potential of using quinacridone derivatives. The measured field-effect mobility of the pristine PQCTQx film was 6.1 × 10⁻³ cm²/(V·s). A PQCTQx film heat-treated at 150 °C exhibited good field-effect performances with a hole mobility of 1.2 × 10⁻² cm²/(V·s). The improved OFET behaviors resulting from the mild thermal treatment was attributed to improved packing of the molecules in the film, as determined using X-ray diffraction, and to decreased channel resistance. Full article

► Show Figures

Graphical abstract

21 pages, 10923 KiB

Open AccessArticle

Multifunctional Nanocomposite Cellulose Fibers Doped in Situ with Silver Nanoparticles

by Olga Rac-Rumijowska, Irena Maliszewska, Marta Fiedot-Toboła, Iwona Karbownik and Helena Teterycz

Polymers 2019, 11(3), 562; https://doi.org/10.3390/polym11030562 - 25 Mar 2019

Cited by 24 | Viewed by 4482

Abstract

This paper presents a method for the preparation of nanocomposite cellulose fibers doped with silver nanoparticles (AgNPs), as well as the effect of silver nanoparticles on the structure and properties of fibers. The fibers were obtained by an environmentally friendly method using N-Methylmorpholine [...] Read more.

This paper presents a method for the preparation of nanocomposite cellulose fibers doped with silver nanoparticles (AgNPs), as well as the effect of silver nanoparticles on the structure and properties of fibers. The fibers were obtained by an environmentally friendly method using N-Methylmorpholine N-oxide (NMMO) as a solvent, in a non-polluting closed system. Doping with silver nanoparticles was carried out as a direct (in situ) reduction of Ag⁺ ions in the presence of a stabilizing agent during the preparation of the spinning solution. SEM images of the surface and cross section of the fibers showed that the distribution of nanoparticles in the fibers’ volume was uniform. The fibers exhibited very good antibacterial properties in relation to Staphylococcus aureus, Escherichia coli, Acinetobacter baumannii, and Candida albicans. Flammability analysis showed that the fibers were subjected to a one-stage combustion process and that the silver nanoparticles reduced the heat release rate (HRR) of the fibers by 36%. TG studies showed that the modification of cellulose fibers with silver nanoparticles promoted the formation of mill scale in the combustion of fibers, which was directly related to the reduction of flammability. Tests of the electrical properties showed that the linear resistance of cellulose fibers containing 3 wt % silver was 10⁸ Ω/cm. Full article

(This article belongs to the Special Issue Cellulose and Renewable Materials)

► Show Figures

Graphical abstract

12 pages, 1858 KiB

Open AccessArticle

Polymer Pen Lithography-Fabricated DNA Arrays for Highly Sensitive and Selective Detection of Unamplified Ganoderma Boninense DNA

by Ekta Rani, Siti Akhtar Mohshim, Muhammad Zamharir Ahmad, Royston Goodacre, Shahrul Ainliah Alang Ahmad and Lu Shin Wong

Polymers 2019, 11(3), 561; https://doi.org/10.3390/polym11030561 - 25 Mar 2019

Cited by 14 | Viewed by 5095

Abstract

There is an increasing demand for lithography methods to enable the fabrication of diagnostic devices for the biomedical and agri-food sectors. In this regard, scanning probe lithography methods have emerged as a possible approach for this purpose, as they are not only convenient, [...] Read more.

There is an increasing demand for lithography methods to enable the fabrication of diagnostic devices for the biomedical and agri-food sectors. In this regard, scanning probe lithography methods have emerged as a possible approach for this purpose, as they are not only convenient, robust and accessible, but also enable the deposition of “soft” materials such as complex organic molecules and biomolecules. In this report, the use of polymer pen lithography for the fabrication of DNA oligonucleotide arrays is described, together with the application of the arrays for the sensitive and selective detection of Ganoderma boninense, a fungal pathogen of the oil palm. When used in a sandwich assay format with DNA-conjugated gold nanoparticles, this system is able to generate a visually observable result in the presence of the target DNA. This assay is able to detect as little as 30 ng of Ganoderma-derived DNA without any pre-amplification and without the need for specialist laboratory equipment or training. Full article

(This article belongs to the Special Issue Lithography with Polymer Stamp Techniques)

► Show Figures

Graphical abstract

18 pages, 1213 KiB

Open AccessEditor’s ChoiceReview

Polymeric Antimicrobial Food Packaging and Its Applications

by Tianqi Huang, Yusheng Qian, Jia Wei and Chuncai Zhou

Polymers 2019, 11(3), 560; https://doi.org/10.3390/polym11030560 - 25 Mar 2019

Cited by 217 | Viewed by 18280

Abstract

Food corruption and spoilage caused by food-borne pathogens and microorganisms is a serious problem. As a result, the demand for antibacterial drugs in food packaging is growing. In this review, biodegradable and non-biodegradable materials for food packaging are discussed based on their properties. [...] Read more.

Food corruption and spoilage caused by food-borne pathogens and microorganisms is a serious problem. As a result, the demand for antibacterial drugs in food packaging is growing. In this review, biodegradable and non-biodegradable materials for food packaging are discussed based on their properties. Most importantly, antibacterial agents are essential to inhibit the growth of bacteria in food. To keep food fresh and prolong the shelf life, different kinds of antibacterial agents were used. The composition and application of natural antibacterial agents and synthetic antibacterial agents are discussed. Compared with natural antibacterial agents, synthetic antibacterial agents have the advantages of low cost and high activity, but their toxicity is usually higher than that of natural antibacterial agents. Finally, future development of antimicrobial food packaging is proposed. It is an urgent problem for researchers to design and synthesize antibacterial drugs with high efficiency and low toxicity. Full article

► Show Figures

Graphical abstract

12 pages, 2871 KiB

Open AccessArticle

Influence of Various Climatic Conditions on the Structural Changes of Semicrystalline PLA Spun-Bonded Mulching Nonwovens during Outdoor Composting

by Michał Puchalski, Piotr Siwek, Nicolay Panayotov, Małgorzata Berova, Stanisława Kowalska and Izabella Krucińska

Polymers 2019, 11(3), 559; https://doi.org/10.3390/polym11030559 - 25 Mar 2019

Cited by 20 | Viewed by 4014

Abstract

This study analyzed the structural changes of semicrystalline polylactide (PLA) in the form of spun-bonded mulching nonwovens, during outdoor composting. The investigation was carried out at the microstructural, supramolecular and molecular levels using scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and the [...] Read more.

This study analyzed the structural changes of semicrystalline polylactide (PLA) in the form of spun-bonded mulching nonwovens, during outdoor composting. The investigation was carried out at the microstructural, supramolecular and molecular levels using scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD) and the viscosity method, respectively. The obtained experimental results revealed how the popular outdoor composting method, realized under two different European climatic conditions (in Poland and in Bulgaria), affects the degradation of PLA nonwoven, designed for agriculture use. The results showed the insignificant influence of the climatic conditions and prepared compost mixtures on the molecular and micromorphological structure of PLA spun-bonded mulching nonwovens, with a visible increase in crystallinity after the first year of composting. Significant changes were observed only after the second year of composting, which indicates the resistance of semicrystalline PLA to degradation in outdoor composting conditions. Full article

(This article belongs to the Special Issue Assessment of the Ageing and Durability of Polymers: Procedures and Reliability)

► Show Figures

Figure 1

17 pages, 3574 KiB

Open AccessArticle

Coordination between Surface Lattice Resonances of Poly(glycidyl Methacrylate) Line Array and Surface Plasmon Resonances of CdS Quantum on Silicon Surface

by Shuenn-Kung Su, Feng-Ping Lin, Chih-Feng Huang, Chien-Hsing Lu and Jem-Kun Chen

Polymers 2019, 11(3), 558; https://doi.org/10.3390/polym11030558 - 25 Mar 2019

Cited by 1 | Viewed by 3056

Abstract

In this work, a unique hybrid system is proposed for one-dimensional gratings comprising of poly(glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CQDs). Generally, the emission of QDs is too weak to be observed in a dry state. Plasmonic resonances of the grating [...] Read more.

In this work, a unique hybrid system is proposed for one-dimensional gratings comprising of poly(glycidyl methacrylate) (PGMA) brushes and CdS quantum dots (CQDs). Generally, the emission of QDs is too weak to be observed in a dry state. Plasmonic resonances of the grating structures can be used to enhance the light emission or absorption of CQDs. The interaction between PGMA plasmonic nanostructures and inorganic CQDs plays a crucial role in engineering the light harvest, notably for optoelectronic applications. Extinction measurements of the hybrid system consisting of a PGMA grating and CQDs are reported. We designed one-dimensional gratings with various resolutions to tune the absorptance peaks of grating. PGMA grating grafted from a 1.5 µm resolution of trench arrays of photoresist exhibited absorptance peak at 395 nm, close to the absorption peak of CQDs, resulting in the photoluminescence enhancement of CQDs on the grating due to high charge carriers’ recombination rate. Generally, the emission of quantum dots occurs under irradiation at characteristic wavelengths. Immobilizing QDs on the grating facilitates the emission of QDs under irradiation of full-wavelength light. Furthermore, the PGMA gratings with CQDs were immersed in various solvents to change the geometries resulting the shift of absorptance peak of grating. The proposed method could be applied for sensing the nature of the surrounding media and vice versa, as well as for various media of solvents. Full article

► Show Figures

Graphical abstract

14 pages, 12974 KiB

Open AccessArticle

Molecular Dynamics Simulation on the Effect of Bonding Pressure on Thermal Bonding of Polymer Microfluidic Chip

by Mingyong Zhou, Xiang Xiong, Dietmar Drummer and Bingyan Jiang

Polymers 2019, 11(3), 557; https://doi.org/10.3390/polym11030557 - 24 Mar 2019

Cited by 18 | Viewed by 6168

Abstract

Thermal bonding technology is the most commonly used approach in bonding injection-molded microfluidic chips. Although the bonding mechanism is still under debate, the molecular dynamics (MD) method can provide insight into the bonding process on a macromolecular level. In this study, MD simulations [...] Read more.

Thermal bonding technology is the most commonly used approach in bonding injection-molded microfluidic chips. Although the bonding mechanism is still under debate, the molecular dynamics (MD) method can provide insight into the bonding process on a macromolecular level. In this study, MD simulations for thermal bonding of PMMA substrate and cover sheet were performed. The molecule configuration and density distribution during the thermal bonding process were studied. The effects of bonding pressure on the equivalent strain, joining energy and diffusion coefficient were investigated. The debonding process was simulated to analyze the bonding strength and failure mechanism. Simulation results show that penetration mainly takes place near the interface area. Although the final density increases slightly with increasing pressure, the bonding interface is still insufficiently filled. The equivalent strain grows faster than that in the later stage because of the gap at the interface. The bonding pressure shows clear effects on the joining energy, diffusion coefficient and stress–strain behavior. Tensile failure occurs at the interface, with PMMA chains stretched between two layers. The majority of the change in potential energy is correlated with the change in non-bonded energy. At yield strain, the low-density defect at the interface weakens the tensile strength of bonded chip. Full article

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

► Show Figures

Graphical abstract

15 pages, 3240 KiB

Open AccessEditor’s ChoiceArticle

Exploring Next-Generation Engineering Bioplastics: Poly(alkylene furanoate)/Poly(alkylene terephthalate) (PAF/PAT) Blends

by Niki Poulopoulou, Nejib Kasmi, Maria Siampani, Zoi N. Terzopoulou, Dimitrios N. Bikiaris, Dimitris S. Achilias, Dimitrios G. Papageorgiou and George Z. Papageorgiou

Polymers 2019, 11(3), 556; https://doi.org/10.3390/polym11030556 - 23 Mar 2019

Cited by 39 | Viewed by 6755

Abstract

Polymers from renewable resources and especially strong engineering partially aromatic biobased polyesters are of special importance for the evolution of bioeconomy. The fabrication of polymer blends is a creative method for the production of tailor-made materials for advanced applications that are able to [...] Read more.

Polymers from renewable resources and especially strong engineering partially aromatic biobased polyesters are of special importance for the evolution of bioeconomy. The fabrication of polymer blends is a creative method for the production of tailor-made materials for advanced applications that are able to combine functionalities from both components. In this study, poly(alkylene furanoate)/poly(alkylene terephthalate) blends with different compositions were prepared by solution blending in a mixture of trifluoroacetic acid and chloroform. Three different types of blends were initially prepared, namely, poly(ethylene furanoate)/poly(ethylene terephthalate) (PEF/PET), poly(propylene furanoate)/poly(propylene terephthalate) (PPF/PPT), and poly(1,4-cyclohenedimethylene furanoate)/poly(1,4-cycloxehane terephthalate) (PCHDMF/PCHDMT). These blends’ miscibility characteristics were evaluated by examining the glass transition temperature of each blend. Moreover, reactive blending was utilized for the enhancement of miscibility and dynamic homogeneity and the formation of copolymers through transesterification reactions at high temperatures. PEF–PET and PPF–PPT blends formed a copolymer at relatively low reactive blending times. Finally, poly(ethylene terephthalate-co-ethylene furanoate) (PETF) random copolymers were successfully introduced as compatibilizers for the PEF/PET immiscible blends, which resulted in enhanced miscibility. Full article

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

► Show Figures

Graphical abstract

18 pages, 6723 KiB

Open AccessArticle

High-Performance TiO₂ Nanotubes/Poly(aryl ether sulfone) Hybrid Self-Cleaning Anti-Fouling Ultrafiltration Membranes

by Zhi Geng, Xinyu Wang, Hongchuan Jiang, Leilei Zhang, Zhiting Chen, Yong Feng, Wenzhe Geng, Xia Yang, Mingxin Huo and Jing Sun

Polymers 2019, 11(3), 555; https://doi.org/10.3390/polym11030555 - 23 Mar 2019

Cited by 16 | Viewed by 3904

Abstract

A series of novel self-cleaning hybrid photocatalytic ultrafiltration (UF) membranes were fabricated to separate polyacrylamide, which is widely used as a commercial flocculant. To maximize the self-cleaning and anti-fouling properties of hybrid membranes, high surface area TiO₂ nanotubes (TNTs) with excellent photocatalytic [...] Read more.

A series of novel self-cleaning hybrid photocatalytic ultrafiltration (UF) membranes were fabricated to separate polyacrylamide, which is widely used as a commercial flocculant. To maximize the self-cleaning and anti-fouling properties of hybrid membranes, high surface area TiO₂ nanotubes (TNTs) with excellent photocatalytic activity were homogeneously introduced into a poly(aryl ether sulfone) matrix by chemical bonds. The chemical structure, micromorphology, hydrophilicity, separation efficiency, fouling behavior, and self-cleaning property of the prepared hybrid membranes were well characterized and evaluated. For the optimal sample, the flux recovery ratio increased from ~40% to ~80% after simulated sunlight irradiation for 20 min, which was attributable to the homogeneous dispersion and efficient photocatalytic degradation ability of TNTs. Furthermore, the intelligent fabrication strategy enhanced the anti-aging ability of the hybrid membranes via the use of a fluorine-containing poly matrix. This work provided new insight into the fabrication of high-performance self-cleaning inorganic/organic hybrid membranes. Full article

(This article belongs to the Special Issue Polymeric Thin Films and Membranes)

► Show Figures

Graphical abstract

22 pages, 2819 KiB

Open AccessArticle

Ethylene-co-norbornene Copolymerization Using a Dual Catalyst System in the Presence of a Chain Transfer Agent

by Laura Boggioni, Diego Sidari, Simona Losio, Udo M. Stehling, Finizia Auriemma, Anna Malafronte, Rocco Di Girolamo, Claudio De Rosa and Incoronata Tritto

Polymers 2019, 11(3), 554; https://doi.org/10.3390/polym11030554 - 22 Mar 2019

Cited by 15 | Viewed by 5508

Abstract

Ethylene-co-norbornene copolymers were synthesized by a dual catalyst system at three concentrations of norbornene in the feed and variable amounts of ZnEt₂, as a possible chain transfer agent. The dual catalyst system consists of two ansa-metallocenes, isopropyliden(η^5- [...] Read more.

Ethylene-co-norbornene copolymers were synthesized by a dual catalyst system at three concentrations of norbornene in the feed and variable amounts of ZnEt₂, as a possible chain transfer agent. The dual catalyst system consists of two ansa-metallocenes, isopropyliden(η^5-cyclopentadienyl)(η⁵-indenyl)zirconium dichloride (1) and isopropyliden(η⁵-3-methylcyclopentadienyl)(η⁵-fluorenyl)zirconium dichloride (2), activated with dimethylanilinium tetrakis(pentafluorophenyl)borate, in presence of TIBA. Values of norbornene content, molecular mass, glass transition temperature, and reactivity ratios r₁₁ and r₂₁ of copolymers prepared in the presence of 1+2 are intermediate between those of reference copolymers. The study of tensile and elastic properties of ethylene-co-norbornene copolymers (poly(E-co-N)s) gave evidence that copolymers were obtained in part through transfer of polymer chains between different transition metal sites. Mechanical properties are clearly different from those expected from a blend of the parent samples and reveal that copolymers obtained in the presence of 1+2 and ZnEt₂ consist of a reactor blend of segmented chains produced by exchange from 2 to 1 and 1 to 2 acting as the ideal compatibilizer of chains produced by the chain transfer from 1 to 1, and from 2 to 2. Full article

(This article belongs to the Special Issue Catalytic Polymerization)

► Show Figures

Graphical abstract

31 pages, 9874 KiB

Open AccessReview

Polymer-Based Device Fabrication and Applications Using Direct Laser Writing Technology

by Zhen-Lin Wu, Ya-Nan Qi, Xiao-Jie Yin, Xin Yang, Chang-Ming Chen, Jing-Ying Yu, Jia-Chen Yu, Yu-Meng Lin, Fang Hui, Peng-Li Liu, Yu-Xin Liang, Yang Zhang and Ming-Shan Zhao

Polymers 2019, 11(3), 553; https://doi.org/10.3390/polym11030553 - 22 Mar 2019

Cited by 45 | Viewed by 9808

Abstract

Polymer materials exhibit unique properties in the fabrication of optical waveguide devices, electromagnetic devices, and bio-devices. Direct laser writing (DLW) technology is widely used for micro-structure fabrication due to its high processing precision, low cost, and no need for mask exposure. This paper [...] Read more.

Polymer materials exhibit unique properties in the fabrication of optical waveguide devices, electromagnetic devices, and bio-devices. Direct laser writing (DLW) technology is widely used for micro-structure fabrication due to its high processing precision, low cost, and no need for mask exposure. This paper reviews the latest research progresses of polymer-based micro/nano-devices fabricated using the DLW technique as well as their applications. In order to realize various device structures and functions, different manufacture parameters of DLW systems are adopted, which are also investigated in this work. The flexible use of the DLW process in various polymer-based microstructures, including optical, electronic, magnetic, and biomedical devices are reviewed together with their applications. In addition, polymer materials which are developed with unique properties for the use of DLW technology are also discussed. Full article

(This article belongs to the Special Issue Laser processing in polymer research)

► Show Figures

Figure 1

12 pages, 5173 KiB

Open AccessArticle

The Influence of DMDBS on Crystallization Behavior and Crystalline Morphology of Weakly-Phase-Separated Olefin Block Copolymer

by Yongsheng Zhao, Cheng Yao, Tao Chang and Yanling Zhu

Polymers 2019, 11(3), 552; https://doi.org/10.3390/polym11030552 - 22 Mar 2019

Cited by 7 | Viewed by 5041

Abstract

Olefin block copolymer (OBC), with its low hard segments, can form unique space-filling spherulites other than confined-crystallization morphologies, mainly due to its weak phase-separation. In this work, 1,3;2,4-Bis(3,4-dimethylbenzylidene) sorbitol (DMDBS), a well-known nucleating agent, was used to tailor the crystallization behavior and crystalline [...] Read more.

Olefin block copolymer (OBC), with its low hard segments, can form unique space-filling spherulites other than confined-crystallization morphologies, mainly due to its weak phase-separation. In this work, 1,3;2,4-Bis(3,4-dimethylbenzylidene) sorbitol (DMDBS), a well-known nucleating agent, was used to tailor the crystallization behavior and crystalline morphology of OBC. It was found that DMDBS can precipitate within an OBC matrix and self-assemble into crystalline fibrils when cooling from the melt. A non-isothermal crystallization process exhibited an increased crystallization rate and strong composition dependence. During the isothermal crystallization process, DMDBS showed a more obvious nucleating efficiency at a higher crystallization temperature. OBC showed typical spherulites when DMDBS was added. Moreover, a low addition of DMDBS significantly decreased the crystal size, while a large addition of DMDBS induced aggregates, due to the limited miscibility of DMDBS with OBC. The efficient nucleating effect of DMDBS on OBC led to an increased optical transparency for OBC/DMDBS composites. Full article

► Show Figures

Graphical abstract

10 pages, 1712 KiB

Open AccessArticle

Ferrocene-Modified Polyelectrolyte Film-Coated Electrode and Its Application in Glucose Detection

by Zhiping Jiang, Yonggang Shangguan and Qiang Zheng

Polymers 2019, 11(3), 551; https://doi.org/10.3390/polym11030551 - 22 Mar 2019

Cited by 20 | Viewed by 5544

Abstract

A polyelectrolyte film-coated electrode for the quantitative detection of glucose was reported. Carbon nanotubes, graphene oxide and polyelectrolyte with a ferrocenyl group were used to modify an enzyme electrode to facilitate the electron transfer between glucose oxidase and the electrode. Cyclic voltammetry and [...] Read more.

A polyelectrolyte film-coated electrode for the quantitative detection of glucose was reported. Carbon nanotubes, graphene oxide and polyelectrolyte with a ferrocenyl group were used to modify an enzyme electrode to facilitate the electron transfer between glucose oxidase and the electrode. Cyclic voltammetry and amperometric methods were adopted to investigate the effects of different polyelectrolytes and carbon nanomaterials on the electrochemical properties of enzyme electrodes. The results indicate that the ferrocenyl groups on a polyelectrolyte skeleton act as a mediator between the redox center of glucose oxidase and the electrode, which efficiently enhances the electron transfer between a glassy carbon electrode and glucose oxidase. The calibration curve of the sensor shows a linear range from 0.2 to 5 mM for glucose response. The sensor can achieve 95% of the steady-state current within 10 s. The electrodes also present high operational stability and long-term storage stability. Full article

(This article belongs to the Collection Polyelectrolytes)

► Show Figures

Figure 1

13 pages, 3979 KiB

Open AccessArticle

Electrospinning of Ethylene Vinyl Acetate/Carbon Nanotube Nanocomposite Fibers

by Mária Omastová, Eliška Číková and Matej Mičušík

Polymers 2019, 11(3), 550; https://doi.org/10.3390/polym11030550 - 22 Mar 2019

Cited by 19 | Viewed by 5154

Abstract

Nanocomposites, based on an ethylene vinyl acetate (EVA) copolymer with a vinyl acetate content of 34 wt % and varying amounts of multiwall carbon nanotubes (MWCNTs), were prepared by an electrospinning method. The dispersibility of the MWCNTs in the solution was improved by [...] Read more.

Nanocomposites, based on an ethylene vinyl acetate (EVA) copolymer with a vinyl acetate content of 34 wt % and varying amounts of multiwall carbon nanotubes (MWCNTs), were prepared by an electrospinning method. The dispersibility of the MWCNTs in the solution was improved by using cholesteryl 1-pyrenecarboxylate (PyChol) as a compatibilizer. The transmission electron microscopy images showed that the MWCNTs were aligned inside of the elastomeric matrix by the electrospinning process. The morphologies of the fibers were evaluated by scanning electron microscopy. When the amount of MWCNTs in the polymer solution reached 3 wt %, fibers with a diameter of 846 ± 447 nm were prepared. The chemical composition of the prepared fibers was investigated by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR results confirmed the presence of a carboxyl group, originating from the presence of PyChol. XPS results showed that the EVA fibers produced by electrospinning were oxidized in ethylene units, when comparing the spectra of the original EVA granules, but the presence of MWCNTs enhanced the stability of the EVA. The thermal stabilities of the fibers were tested with thermogravimetric analysis. The results confirmed that the presence of MWCNTs inside the fibers enhanced the thermal stabilities of the prepared nanocomposites. Full article

(This article belongs to the Special Issue Nanostructured Polymers and Nanocomposites)

► Show Figures

Figure 1

19 pages, 8064 KiB

Open AccessEditor’s ChoiceArticle

Electrical and Thermal Conductivity of Polylactic Acid (PLA)-Based Biocomposites by Incorporation of Nano-Graphite Fabricated with Fused Deposition Modeling

by Rui Guo, Zechun Ren, Hongjie Bi, Min Xu and Liping Cai

Polymers 2019, 11(3), 549; https://doi.org/10.3390/polym11030549 - 22 Mar 2019

Cited by 87 | Viewed by 7509

Abstract

The aim of the study was to improve the electrical and thermal conductivity of the polylactic acid/wood flour/thermoplastic polyurethane composites by Fused Deposition Modeling (FDM). The results showed that, when the addition amount of nano-graphite reached 25 pbw, the volume resistivity of the [...] Read more.

The aim of the study was to improve the electrical and thermal conductivity of the polylactic acid/wood flour/thermoplastic polyurethane composites by Fused Deposition Modeling (FDM). The results showed that, when the addition amount of nano-graphite reached 25 pbw, the volume resistivity of the composites decreased to 10⁸ Ω·m, which was a significant reduction, indicating that the conductive network was already formed. It also had good thermal conductivity, mechanical properties, and thermal stability. The adding of the redox graphene (rGO) combined with graphite into the composites, compared to the tannic acid-functionalized graphite or the multi-walled carbon nanotubes, can be an effective method to improve the performance of the biocomposites, because the resistivity reduced by one order magnitude and the thermal conductivity increased by 25.71%. Models printed by FDM illustrated that the composite filaments have a certain flexibility and can be printed onto paper or flexible baseplates. Full article

► Show Figures

Figure 1

10 pages, 2875 KiB

Open AccessArticle

Removing Pb(II) Ions from Aqueous Solution by a Promising Absorbent of Tannin-Immobilized Cellulose Microspheres

by Ying Pei, Gaoqiang Xu, Xiao Wu, Keyong Tang and Guozhen Wang

Polymers 2019, 11(3), 548; https://doi.org/10.3390/polym11030548 - 22 Mar 2019

Cited by 21 | Viewed by 4013

Abstract

Tannin/cellulose microspheres (T/C) were successfully prepared via a facile homogeneous reaction in a water/oil (W/O) emulsion for removing Pb(II) ions from aqueous solution. The structure of the microspheres was characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and a zeta potential [...] Read more.

Tannin/cellulose microspheres (T/C) were successfully prepared via a facile homogeneous reaction in a water/oil (W/O) emulsion for removing Pb(II) ions from aqueous solution. The structure of the microspheres was characterized by scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, and a zeta potential test. The effects of pH, adsorbent dosage, contact time, and temperature on adsorption ability were investigated. The results showed that T/C microspheres could combine Pb(II)ions via electrostatic attractions and physical adsorption. Adsorption kinetics could be better described by the pseudo-second-order kinetic model. The adsorption behaviors were in agreement with the Langmuir adsorption isotherm model with a fitting correlation coefficient of 0.9992. The maximum adsorption capacity was 23.75 mg/g from the Langmuir isotherm evaluation at 308K with an initial pH of 5. The results suggested that tannin/cellulose microspheres could be a low-cost and effective adsorbent for removing Pb(II) ions from aqueous solution. Full article

(This article belongs to the Special Issue Natural Compounds for Natural Polymers)

► Show Figures

Graphical abstract

15 pages, 4079 KiB

Open AccessArticle

(Bio)degradable Polymeric Materials for Sustainable Future—Part 2: Degradation Studies of P(3HB-co-4HB)/Cork Composites in Different Environments

by Sebastian Jurczyk, Marta Musioł, Michał Sobota, Magdalena Klim, Anna Hercog, Piotr Kurcok, Henryk Janeczek and Joanna Rydz

Polymers 2019, 11(3), 547; https://doi.org/10.3390/polym11030547 - 22 Mar 2019

Cited by 18 | Viewed by 4663

Abstract

The degree of degradation of pure poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and its composites with cork incubated under industrial and laboratory composting conditions was investigated. The materials were parallelly incubated in distilled water at 70 °C as a reference experiment (abiotic condition). [...] Read more.

The degree of degradation of pure poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] and its composites with cork incubated under industrial and laboratory composting conditions was investigated. The materials were parallelly incubated in distilled water at 70 °C as a reference experiment (abiotic condition). It was demonstrated that addition of the cork into polyester strongly affects the matrix crystallinity. It influences the composite degradation independently on the degradation environment. Moreover, the addition of the cork increases the thermal stability of the obtained composites; this was related to a smaller reduction in molar mass during processing. This phenomenon also had an influence on the composite degradation process. The obtained results suggest that the addition of cork as a natural filler in various mass ratios to the composites enables products with different life expectancies to be obtained. Full article

(This article belongs to the Special Issue Biodegradable Polymers - Where We Are and Where to Going)

► Show Figures

Figure 1

13 pages, 4439 KiB

Open AccessArticle

Facile Preparation of Highly Conductive Poly(amide-imide) Composite Films beyond 1000 S m⁻¹ through Ternary Blend Strategy

by Yanbin Wang, Huang Yu, Yongchao Li, Teng Wang, Tao Xu, Jinxing Chen, Zicheng Fan, Yufeng Wang and Biaobing Wang

Polymers 2019, 11(3), 546; https://doi.org/10.3390/polym11030546 - 22 Mar 2019

Cited by 33 | Viewed by 4780

Abstract

Highly conductive thin films with suitable mechanical performances play a significant role in modern electronic industry. Herein, a series of ternary conductive polymer composites were fabricated by incorporating carbon black (CB) into binary conductive polymer composites of poly(amide-imide) (PAI) and polyaniline (PANI) to [...] Read more.

Highly conductive thin films with suitable mechanical performances play a significant role in modern electronic industry. Herein, a series of ternary conductive polymer composites were fabricated by incorporating carbon black (CB) into binary conductive polymer composites of poly(amide-imide) (PAI) and polyaniline (PANI) to enhance their mechanical and conductive properties simultaneously. By varying the composition of PAI/PANI/CB ternary films, the conductivity enhanced by two orders of magnitude compared with the sum of PAI/PANI and PAI/CB binary conductive polymer composites, and a high conductivity of 1160 S m⁻¹ was achieved. The improved conductivity is mainly because much more continuous conductive networks were constructed in the ternary conductive polymer composites. With the help of the unusual morphology, the tensile strength was also enhanced by more than 80% from 21 to 38 MPa. The origin for the improved morphology was discussed for further improvement. Full article

(This article belongs to the Special Issue Conducting Polymers)

► Show Figures

Figure 1

17 pages, 3979 KiB

Open AccessArticle

Construction of Carbon Microspheres-Based Silane Melamine Phosphate Hybrids for Flame Retardant Poly(ethylene Terephthalate)

by Baoxia Xue, Ruihong Qin, Jie Wang, Mei Niu, Yongzhen Yang and Xuguang Liu

Polymers 2019, 11(3), 545; https://doi.org/10.3390/polym11030545 - 22 Mar 2019

Cited by 13 | Viewed by 4141

Abstract

To improve the flame retardancy and inhibit the smoke of poly(ethylene terephthalate) (PET), carbon microspheres (CMSs)-based melamine phosphate (MP) hybrids (MP-CMSs) were constructed in situ with the introduction of CMSs into the hydrothermal reaction system of MP. The integrated MP-CMSs were modified by [...] Read more.

To improve the flame retardancy and inhibit the smoke of poly(ethylene terephthalate) (PET), carbon microspheres (CMSs)-based melamine phosphate (MP) hybrids (MP-CMSs) were constructed in situ with the introduction of CMSs into the hydrothermal reaction system of MP. The integrated MP-CMSs were modified by 3-Aminopropyltriethoxysilane (APTS) to obtain the silane MP-CMSs (SiMP-CMSs) to strengthen the interface binding between the MP-CMSs and PET matrix. The results showed that the SiMP layer was loaded on the CMSs surface. The addition of only 3% SiMP-CMSs increased the limiting oxygen index (LOI) value of the PET from 21% ± 0.1% to 27.7% ± 0.3%, reaching a V-0 burning rate. The SiMP-CMSs not only reduced heat damage, but also inhibited the smoke release during PET combustion, whereupon the peak heat release rate (pk-HRR) reduced from 513.2 to 221.7 kW/m², and the smoke parameters (SP) decreased from 229830.2 to 81892.3 kW/kg. The fire performance index (FPI) rose from 0.07 m²s/kW to 0.17 m²s/kW, demonstrating the lower fire risk. The proportion of the flame-retardant mode in the physical barrier, flame inhibition, and char effects were recorded as 44.53%, 19.04%, and 9.04%, respectively. Full article

(This article belongs to the Special Issue Thermal Insulating and Fire-Resistant Polymer Composites)

► Show Figures

Graphical abstract

11 pages, 2056 KiB

Open AccessArticle

Optimizing Polymer Solar Cells Using Non-Halogenated Solvent Blends

by Guler Kocak, Desta Gedefaw and Mats R. Andersson

Polymers 2019, 11(3), 544; https://doi.org/10.3390/polym11030544 - 22 Mar 2019

Cited by 8 | Viewed by 4261

Abstract

More environmentally friendly polymer solar cells were constructed using a conjugated polymer, poly (2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3′,2′h][1,5] naphthyridine-5,10-dione, PTNT, as a donor material in combination with PC₇₁BM as an acceptor in a bulk heterojunction device structure. A non-halogenated processing solvent (o-xylene) and [...] Read more.

More environmentally friendly polymer solar cells were constructed using a conjugated polymer, poly (2,5-thiophene-alt-4,9-bis(2-hexyldecyl)-4,9-dihydrodithieno[3,2-c:3′,2′h][1,5] naphthyridine-5,10-dione, PTNT, as a donor material in combination with PC₇₁BM as an acceptor in a bulk heterojunction device structure. A non-halogenated processing solvent (o-xylene) and solvent additives that are less harmful to the environment such as 1-methoxynaphthalene (MN) and 1-phenylnaphthalene (PN) were used throughout the study as processing solvents. The most widely used halogenated solvent additives (1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN)) were also used for comparison and to understand the effect of the type of solvent additives on the photovoltaic performances. Atomic force microscopy (AFM) was employed to investigate the surface morphology of the films prepared in the presence of the various additives. The best-performing polymer solar cells provided a high open-circuit voltage of 0.9 V, an efficient fill factor of around 70%, and a highest power conversion efficiency (PCE) of over 6% with the use of the eco-friendlier o-xylene/MN solvent systems. Interestingly, the solvent blend which is less harmful and with low environmental impact gave a 20% rise in PCE as compared to an earlier reported device efficiency that was processed from the chlorinated solvent o-dichlorobenzene (o-DCB). Full article

(This article belongs to the Special Issue Nanotechnology of Polymers and Biomaterials)

► Show Figures

Graphical abstract

19 pages, 3970 KiB

Open AccessArticle

d-, l- and d,l-Tryptophan-Based Polyamidoamino Acids: pH-Dependent Structuring and Fluorescent Properties

by Federica Lazzari, Amedea Manfredi, Jenny Alongi, Daniele Marinotto, Paolo Ferruti and Elisabetta Ranucci

Polymers 2019, 11(3), 543; https://doi.org/10.3390/polym11030543 - 22 Mar 2019

Cited by 14 | Viewed by 6770

Abstract

Chiral polyamidoamino acids were obtained by polyaddition of N,N’-methylenebisacrylamide with d-, d,l- and l-tryptophan (M-d-Trp, M-d,l-Trp and M-l-Trp). l-tryptophan/glycine copolymers, M-G-l-Trp₅, M-G-l-Trp [...] Read more.

Chiral polyamidoamino acids were obtained by polyaddition of N,N’-methylenebisacrylamide with d-, d,l- and l-tryptophan (M-d-Trp, M-d,l-Trp and M-l-Trp). l-tryptophan/glycine copolymers, M-G-l-Trp₅, M-G-l-Trp₁₀, M-G-l-Trp₂₀ and M-G-l-Trp_40, were prepared from l-tryptophan/glycine mixtures. These polymers were amphoteric, with acid-base properties similar to those of the parent amino acids. The l-tryptophan/glycine copolymers with high glycine content were water soluble in the pH range 2-12. M-G-l-Trp₄₀ showed a solubility gap centred at pH 4.5 and all tryptophan homopolymers were soluble only at pH > 7. Dynamic light scattering measurements performed in their solubility ranges, namely 2-11 M-G-l-Trp₅, M-G-l-Trp₁₀ and M-G-l-Trp₂₀ and 7-11 for M-G-l-Trp₄₀, M-d-Trp, M-l-Trp and M-d,l-Trp, showed that the size of all samples did not significantly vary with pH. Both M-l-Trp and M-G-l-Trp copolymers showed pH-dependent circular dichroism spectra in the wavelength interval 200–280 nm, revealing structuring. All samples were fluorescent. Their emission spectra were unstructured and, if normalized for their tryptophan content, almost superimposable at the same pH, providing evidence that only tryptophan governed the photoluminescence properties. Changing pH induced in all cases a slight shift of the emission wavelength maximum ascribed to the modification of the microenvironment surrounding the indole ring induced by different protonation degrees. Full article

(This article belongs to the Special Issue Bioinspired and Biomimetic Polymers)

► Show Figures

Figure 1

12 pages, 2098 KiB

Open AccessArticle

Influences of Interface Properties on the Performance of Fiber-Reinforced Asphalt Binder

by Yinghao Miao, Ting Wang and Linbing Wang

Polymers 2019, 11(3), 542; https://doi.org/10.3390/polym11030542 - 22 Mar 2019

Cited by 43 | Viewed by 4062

Abstract

This paper presents an experimental study about the influence of interfacial properties on the performance of fiber-reinforced asphalt. In this study, four types of fiber including one fiber-reinforced plastic (FRP), two lignin fibers, and one basalt fiber are used, and also four types [...] Read more.

This paper presents an experimental study about the influence of interfacial properties on the performance of fiber-reinforced asphalt. In this study, four types of fiber including one fiber-reinforced plastic (FRP), two lignin fibers, and one basalt fiber are used, and also four types of asphalt: Asphalt No. 90, asphalt No. 70, one styrene-butadiene-styrene (SBS) modified asphalt, and asphalt rubber are used. The surface energy parameters of various asphalts and fibers and the shear strength of various fiber-reinforced asphalts are measured. On the basis of these measurements, the influences of surface properties of asphalt and fiber on the performance of fiber-reinforced asphalt are analyzed. The results show that the shear strength of asphalt binder can be significantly increased by adding fibers, and the reinforcement effect is closely related to the types of asphalt and fiber. It was discovered, for the same asphalt, that the basalt fiber has the best reinforcement effect, followed by the two lignin fibers, and the FRP. For the same fiber, asphalt rubber was the most reinforced, followed by the SBS modified asphalt, asphalt No. 70 and asphalt No. 90. It was also discovered, for the same asphalt, the higher the surface energy of the fiber, the better the fiber reinforcement effect. The analysis indicates a good correlation between the work of adhesion between asphalt and fiber and the effect of fiber reinforcement. The results can be used as a basis for the selection of the proper fiber-asphalt combination to improve fiber reinforcement effects. Full article

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Polymers, Volume 11, Issue 3 (March 2019) – 185 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI