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15 pages, 4399 KiB

Open AccessArticle

Enhanced Electrical Conductivity of Carbon Nanotube-Based Elastomer Nanocomposites Prepared by Microwave Curing

by Blake Herren, Preston Larson, Mrinal C. Saha and Yingtao Liu

Polymers 2019, 11(7), 1212; https://doi.org/10.3390/polym11071212 - 26 Jul 2019

Cited by 23 | Viewed by 7605

Abstract

Nanocomposites consisting of polydimethylsiloxane (PDMS) and well-dispersed carbon nanotubes (CNT) can be cured by microwave radiation within a minute, forming a conductive network within the cured materials. Microwave irradiation delivers energy directly to the inner core of the nanocomposites by heating CNTs and [...] Read more.

Nanocomposites consisting of polydimethylsiloxane (PDMS) and well-dispersed carbon nanotubes (CNT) can be cured by microwave radiation within a minute, forming a conductive network within the cured materials. Microwave irradiation delivers energy directly to the inner core of the nanocomposites by heating CNTs and initiating rapid polymerization of the elastomer. In this paper, nanocomposites were fabricated with CNT loadings between 0.5 wt.%–2.5 wt.% via microwave irradiation. Key properties of the nanocomposites including electrical conductivity, microstructures, CNT distribution, density, and surface effects were all characterized. The properties of microwave-cured nanocomposites were compared with those manufactured by the thermal method using a conventional oven. The microwave-curing method substantially increased the electrical conductivity of the nanocomposites due to the improved nanoparticle dispersion and likely CNT alignment. Optimal microwave-curing parameters were identified to further improve the conductivity of the nanocomposites with lowest CNT loading. A conductivity enhancement of 142.8% over thermally cured nanocomposites was achieved for nanocomposites with 1 wt.% CNTs cured via one-step microwave irradiation. Full article

(This article belongs to the Special Issue Conducting Polymers)

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14 pages, 2588 KiB

Open AccessArticle

Stretchable Conductive Hybrid Films Consisting of Cubic Silsesquioxane-capped Polyurethane and Poly(3-hexylthiophene)

by Keigo Kato, Masayuki Gon, Kazuo Tanaka and Yoshiki Chujo

Polymers 2019, 11(7), 1195; https://doi.org/10.3390/polym11071195 - 17 Jul 2019

Cited by 11 | Viewed by 3906

Abstract

We fabricated stretchable and electric conductive hybrids consisting of polyhedral oligomeric silsesquioxane (POSS)-capped polyurethane (PUPOSS) and doped poly(3-hexylthiophene) (P3HT). In order to realize robust films coexisting polar conductive components in hydrophobic elastic matrices, we employed POSS introduced into the terminals of the polyurethane [...] Read more.

We fabricated stretchable and electric conductive hybrids consisting of polyhedral oligomeric silsesquioxane (POSS)-capped polyurethane (PUPOSS) and doped poly(3-hexylthiophene) (P3HT). In order to realize robust films coexisting polar conductive components in hydrophobic elastic matrices, we employed POSS introduced into the terminals of the polyurethane chains as a compatibilizer. Through the simple mixing and drop-casting with the chloroform solutions containing doped P3HT and polyurethane polymers, homogeneous hybrid films were obtained. From the conductivity and mechanical measurements, it was indicated that hybrid materials consisting of PUPOSS and doped P3HT showed high conductivity and stretchability even with a small content of doped P3HT. From the mechanical studies, it was proposed that POSS promoted aggregation of doped P3HT in the films, and ordered structures should be involved in the aggregates. Efficient carrier transfer could occur through the POSS-inducible ordered structures in the aggregates. Full article

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9 pages, 1741 KiB

Open AccessCommunication

Synthesis and Thermoelectric Properties of Selenium Nanoparticles Coated with PEDOT:PSS

by Chingu Kim, Jiyeon Hong and Ji-Woong Park

Polymers 2019, 11(6), 1052; https://doi.org/10.3390/polym11061052 - 17 Jun 2019

Cited by 14 | Viewed by 4876

Abstract

We synthesized a hybrid nanocomposite comprised of selenium nanoparticles coated with a thin layer of a conductive polymer, poly(3,4-ethylenedioxythiophene), and studied its thermoelectric properties. The conductive polymer layer on the surface of nanoparticles in the composites formed a percolating network running between the [...] Read more.

We synthesized a hybrid nanocomposite comprised of selenium nanoparticles coated with a thin layer of a conductive polymer, poly(3,4-ethylenedioxythiophene), and studied its thermoelectric properties. The conductive polymer layer on the surface of nanoparticles in the composites formed a percolating network running between the stacked nanoparticles, exhibiting an electrical conductivity close to or higher than that of pure polymer. The thermoelectric power factor of the resulting composite was higher than that of individual polymer or selenium nanoparticles. We further increased the electrical conductivity of the composite by thermal annealing, thereby improving the power factor to 15 μW/cmK² which is nine times higher than that of the polymer. Full article

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13 pages, 2496 KiB

Open AccessArticle

Conductivity and Density of States of New Polyphenylquinoline

by Shamil R. Saitov, Dmitriy V. Amasev, Alexey R. Tameev, Vladimir V. Malov, Marine G. Tedoradze, Valentin M. Svetlichnyi, Lyudmila A. Myagkova, Elena N. Popova and Andrey G. Kazanskii

Polymers 2019, 11(6), 934; https://doi.org/10.3390/polym11060934 - 29 May 2019

Cited by 2 | Viewed by 3140

Abstract

Electrical, photoelectrical, and optical properties of thin films of a new heat-resistant polyphenylquinoline synthesized using facile methods were investigated. An analysis of the obtained temperature dependences of the dark conductivity and photoconductivity indicates the hopping mechanism of conductivity over localized states arranging at [...] Read more.

Electrical, photoelectrical, and optical properties of thin films of a new heat-resistant polyphenylquinoline synthesized using facile methods were investigated. An analysis of the obtained temperature dependences of the dark conductivity and photoconductivity indicates the hopping mechanism of conductivity over localized states arranging at the energy distance of 0.8 eV from the Fermi level located inside the band gap of the investigated material. The optical band gap of the studied material was estimated from an analysis of the spectral dependences of the photoconductivity and absorption coefficient before (1.8–1.9 eV) and after (2.0–2.2 eV) annealing at temperatures exceeding 100 °C. The Gaussian character of the distribution of the localized states of density inside the band gap near the edges of the bands was established. A mechanism of changes in the optical band gap of the investigating polymer under its annealing is proposed. Full article

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13 pages, 2909 KiB

Open AccessArticle

Comparative Analysis of Fluorinated Anions for Polypyrrole Linear Actuator Electrolytes

by Nguyen Quang Khuyen, Zane Zondaka, Madis Harjo, Janno Torop, Tarmo Tamm and Rudolf Kiefer

Polymers 2019, 11(5), 849; https://doi.org/10.3390/polym11050849 - 10 May 2019

Cited by 26 | Viewed by 3716

Abstract

Either as salts or room temperature ionic liquids, fluorinated anion-based electrolytes have been a common choice for ionic electroactive polymer actuators, both linear and bending. In the present work, propylene carbonate solutions of four electrolytes of the three hugely popular anions—triflouromethanesulfonate, bis(trifluoromethane)sulfonimide, and [...] Read more.

Either as salts or room temperature ionic liquids, fluorinated anion-based electrolytes have been a common choice for ionic electroactive polymer actuators, both linear and bending. In the present work, propylene carbonate solutions of four electrolytes of the three hugely popular anions—triflouromethanesulfonate, bis(trifluoromethane)sulfonimide, and hexafluorophosphate were compared and evaluated in polypyrrole linear actuators. The actuation direction, the characteristics—performance relations influence the behavior of the actuators. Isotonic Electro-chemo-mechanical deformation (ECMD) measurements were performed to study the response of the PPy/DBS samples. The highest strain for pristine PPy/DBS linear actuators was found in range of 21% for LiTFSI, while TBAPF₆ had the least cation involvement, suggesting the potential for application in durable and controllable actuators. Interesting cation effects on the actuation of the same anions (CF₃SO₃⁻) were also observed. Full article

(This article belongs to the Special Issue Conducting Polymers)

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15 pages, 4333 KiB

Open AccessArticle

Characterization of Reduced and Surface-Modified Graphene Oxide in Poly(Ethylene-co-Butyl Acrylate) Composites for Electrical Applications

by Carmen Cobo Sánchez, Martin Wåhlander, Mattias Karlsson, Diana C. Marin Quintero, Henrik Hillborg, Eva Malmström and Fritjof Nilsson

Polymers 2019, 11(4), 740; https://doi.org/10.3390/polym11040740 - 24 Apr 2019

Cited by 7 | Viewed by 3906

Abstract

Promising electrical field grading materials (FGMs) for high-voltage direct-current (HVDC) applications have been designed by dispersing reduced graphene oxide (rGO) grafted with relatively short chains of poly (n-butyl methacrylate) (PBMA) in a poly(ethylene-co-butyl acrylate) (EBA) matrix. All rGO-PBMA composites [...] Read more.

Promising electrical field grading materials (FGMs) for high-voltage direct-current (HVDC) applications have been designed by dispersing reduced graphene oxide (rGO) grafted with relatively short chains of poly (n-butyl methacrylate) (PBMA) in a poly(ethylene-co-butyl acrylate) (EBA) matrix. All rGO-PBMA composites with a filler fraction above 3 vol.% exhibited a distinct non-linear resistivity with increasing electric field; and it was confirmed that the resistivity could be tailored by changing the PBMA graft length or the rGO filler fraction. A combined image analysis- and Monte-Carlo simulation strategy revealed that the addition of PBMA grafts improved the enthalpic solubility of rGO in EBA; resulting in improved particle dispersion and more controlled flake-to-flake distances. The addition of rGO and rGO-PBMAs increased the modulus of the materials up to 200% and the strain did not vary significantly as compared to that of the reference matrix for the rGO-PBMA-2 vol.% composites; indicating that the interphase between the rGO and EBA was subsequently improved. The new composites have comparable electrical properties as today’s commercial FGMs; but are lighter and less brittle due to a lower filler fraction of semi-conductive particles (3 vol.% instead of 30–40 vol.%). Full article

(This article belongs to the Special Issue Conducting Polymers)

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12 pages, 2986 KiB

Open AccessArticle

Effect of Sulfonation Degree and PVDF Content on the Structure and Transport Properties of SPEEK/PVDF Blend Membranes

by Shaojian He, Shaoxiong Zhai, Chong Zhang, Yang Xue, Wei Yang and Jun Lin

Polymers 2019, 11(4), 676; https://doi.org/10.3390/polym11040676 - 13 Apr 2019

Cited by 10 | Viewed by 3971

Abstract

Sulfonated poly (ether ether ketone) (SPEEK) with four different sulfonation degrees (SDs) were prepared, and mixed with polyvinylidene fluoride (PVDF) to prepare four series of SPEEK/PVDF blend membranes. The miscibility between SPEEK and PVDF was investigated by observing the micro-morphologies. The miscible blend [...] Read more.

Sulfonated poly (ether ether ketone) (SPEEK) with four different sulfonation degrees (SDs) were prepared, and mixed with polyvinylidene fluoride (PVDF) to prepare four series of SPEEK/PVDF blend membranes. The miscibility between SPEEK and PVDF was investigated by observing the micro-morphologies. The miscible blend membranes were found in the SPEEK/PVDF blend membranes in which either SPEEK had relatively low SD or consisted of low content of one component (either SPEEK or PVDF). The PVDF crystallinity was found to decrease in the SPEEK/PVDF membranes that had better blend miscibility. With the increase of PVDF content, all the blend membranes exhibited the decreased proton conductivity and methanol permeability, and the miscible blend membranes decreased more slowly than the immiscible ones. Full article

(This article belongs to the Special Issue Conducting Polymers)

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11 pages, 1481 KiB

Open AccessArticle

Self-Doped Conjugated Polymeric Binders Improve the Capacity and Mechanical Properties of V₂O₅ Cathodes

by Xiaoyi Li, Hyosung An, Joseph Strzalka, Jodie Lutkenhaus and Rafael Verduzco

Polymers 2019, 11(4), 589; https://doi.org/10.3390/polym11040589 - 1 Apr 2019

Cited by 8 | Viewed by 3885

Abstract

Polymeric binders serve to stabilize the morphology of electrodes by providing adhesion and binding between the various components. Successful binders must serve multiple functions simultaneously, including providing strong adhesion, improving conductivity, and providing electrochemical stability. A tradeoff between mechanical integrity and electrochemical performance [...] Read more.

Polymeric binders serve to stabilize the morphology of electrodes by providing adhesion and binding between the various components. Successful binders must serve multiple functions simultaneously, including providing strong adhesion, improving conductivity, and providing electrochemical stability. A tradeoff between mechanical integrity and electrochemical performance in binders for lithium-ion batteries is one of the many challenges of improving capacity and performance. In this paper, we demonstrate a self-doped conjugated polymer, poly(9,9-bis(4′-sulfonatobutyl)fluorene-alt-co-1,4-phenylene) (PFP), which not only provides mechanical robustness but also improves electrode stability at temperatures as high as 450 °C. The self-doped PFP polymer is comprised of a conjugated polyfluorene backbone with sulfonate terminated side-chains that serve to dope the conjugated polymer backbone, resulting in stable conductivity. Composite electrodes are prepared by blending PFP with V₂O₅ in water, followed by casting and drying. Structural characterization with X-ray diffraction and wide-angle X-ray scattering shows that PFP suppresses the crystallization of V₂O₅ at high temperatures (up to 450 °C), resulting in improved electrode stability during cycling and improved rate performance. This study demonstrates the potential of self-doped conjugated polymers for use as polymeric binders to enhance mechanical, structural, and electrochemical properties. Full article

(This article belongs to the Special Issue Conducting Polymers)

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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 4816

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)

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12 pages, 5892 KiB

Open AccessArticle

Exploring the Critical Factors Limiting Polyaniline Biocompatibility

by Věra Kašpárková, Petr Humpolíček, Jaroslav Stejskal, Zdenka Capáková, Patrycja Bober, Kateřina Skopalová and Marián Lehocký

Polymers 2019, 11(2), 362; https://doi.org/10.3390/polym11020362 - 19 Feb 2019

Cited by 36 | Viewed by 4033

Abstract

Today, the application of polyaniline in biomedicine is widely discussed. However, information about impurities released from polyaniline and about the cytotoxicity of its precursors aniline, aniline hydrochloride, and ammonium persulfate are scarce. Therefore, cytotoxicity thresholds for the individual precursors and their combinations were [...] Read more.

Today, the application of polyaniline in biomedicine is widely discussed. However, information about impurities released from polyaniline and about the cytotoxicity of its precursors aniline, aniline hydrochloride, and ammonium persulfate are scarce. Therefore, cytotoxicity thresholds for the individual precursors and their combinations were determined (MTT assay) and the type of cell death caused by exposition to the precursors was identified using flow-cytometry. Tests on fibroblasts revealed higher cytotoxicity of ammonium persulfate than aniline hydrochloride. Thanks to the synergic effect, both monomers in combination enhanced their cytotoxicities compared with individual substances. Thereafter, cytotoxicity of polyaniline doped with different acids (sulfuric, nitric, phosphoric, hydrochloric, and methanesulfonic) was determined and correlated with impurities present in respective sample (HPLC). The lowest cytotoxicity showed polyaniline doped with phosphoric acid (followed by sulfuric, methanesulfonic, and nitric acid). Cytotoxicity of polyaniline was mainly attributed to the presence of residual ammonium persulfate and low-molecular-weight polar substances. This is crucial information with respect to the purification of polyaniline and production of its cytocompatible form. Full article

(This article belongs to the Special Issue Conducting Polymers)

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18 pages, 6609 KiB

Open AccessArticle

The Different Outcomes of Electrochemical Copolymerisation: 3-Hexylthiophene with Indole, Carbazole or Fluorene

by Karolina Gebka, Tomasz Jarosz and Agnieszka Stolarczyk

Polymers 2019, 11(2), 355; https://doi.org/10.3390/polym11020355 - 18 Feb 2019

Cited by 5 | Viewed by 3774

Abstract

Electrochemical polymerisation is reported to be a method for readily producing copolymers of various conjugated molecules. We employed this method for mixtures of indole, carbazole or fluorene with 3-hexylthiophene (HT), in order to obtain their soluble copolymers. Although polymer films were obtained, infrared [...] Read more.

Electrochemical polymerisation is reported to be a method for readily producing copolymers of various conjugated molecules. We employed this method for mixtures of indole, carbazole or fluorene with 3-hexylthiophene (HT), in order to obtain their soluble copolymers. Although polymer films were obtained, infrared (IR) and Raman investigations showed that instead of the expected linear copolymers, polyindole and polycarbazole N-substituted with HT, as well as a poly(3-hexylthiophene) (PHT)/polyfluorene blend were produced instead. Boron trifluoride diethyl etherate was also used in an attempt to promote copolymerisation, but the produced deposits were found to be highly degraded. Full article

(This article belongs to the Special Issue Conducting Polymers)

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12 pages, 24203 KiB

Open AccessArticle

Polypyrrole Nanowires with Ordered Large Mesopores: Synthesis, Characterization and Applications in Supercapacitor and Lithium/Sulfur Batteries

by Fuxing Yin, Jun Ren, Guoyan Wu, Chengwei Zhang and Yongguang Zhang

Polymers 2019, 11(2), 277; https://doi.org/10.3390/polym11020277 - 7 Feb 2019

Cited by 17 | Viewed by 4436

Abstract

In this work, we report the preparation of polypyrrole nanowires with ordered large mesopores (OMPW) by a simple chemical polymerization method from dual templates synthesized by self-assembling silica nanospheres in porous anodic aluminum oxide (AAO) membrane channels. The obtained OMPW showed a large [...] Read more.

In this work, we report the preparation of polypyrrole nanowires with ordered large mesopores (OMPW) by a simple chemical polymerization method from dual templates synthesized by self-assembling silica nanospheres in porous anodic aluminum oxide (AAO) membrane channels. The obtained OMPW showed a large surface area (231.5 m² g⁻¹), high aspect ratio, and interconnected large mesopores (~23 nm). The OMPW was tested as a supercapacitor electrode and showed a specific capacitance of 453 F g⁻¹ at 0.25 A g⁻¹. A sulfur/OMPW (S/OMPW) cathode was fabricated via a simple solution method and a heat-treatment process for lithium/sulfur batteries (LSBs). The S/OMPW composite delivered a large discharge capacity reaching 1601 mAh g⁻¹ at the initial cycle, retaining 1014 mAh g⁻¹ at the 100th cycle at 0.1 C. The great electrochemical performances of the OMPW capacitor electrode and S/OMPW composite were attributed to the large specific surface areas and interconnected mesopores that could supply more active sites for the electrochemical reaction and facilitate mass transfer. Full article

(This article belongs to the Special Issue Conducting Polymers)

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11 pages, 6925 KiB

Open AccessEditor’s ChoiceArticle

Enhanced Proton Conductivity in Sulfonated Poly(ether ether ketone) Membranes by Incorporating Sodium Dodecyl Benzene Sulfonate

by Shaoxiong Zhai, Wenxu Dai, Jun Lin, Shaojian He, Bing Zhang and Lin Chen

Polymers 2019, 11(2), 203; https://doi.org/10.3390/polym11020203 - 24 Jan 2019

Cited by 34 | Viewed by 6795

Abstract

It is of great importance to improve the proton conductivity of proton exchange membranes by easy-handling and cost-efficient approaches. In this work, we incorporated a commercially obtained surfactant, sodium dodecyl benzene sulfonate (SDBS), into sulfonated poly(ether ether ketone) (SPEEK) through solution casting to [...] Read more.

It is of great importance to improve the proton conductivity of proton exchange membranes by easy-handling and cost-efficient approaches. In this work, we incorporated a commercially obtained surfactant, sodium dodecyl benzene sulfonate (SDBS), into sulfonated poly(ether ether ketone) (SPEEK) through solution casting to prepare SPEEK/SDBS membranes. When no more than 10 wt % SDBS was added, the SDBS was well dissolved into the SPEEK matrix, and the activation energy for the proton transfer in the SPEEK/SDBS membranes was greatly reduced, leading to significant enhancement of the membrane proton conductivity. Compared with the SPEEK control membrane, the SPEEK/SDBS membrane with 10 wt % SDBS showed a 78% increase in proton conductivity, up from 0.051 S cm⁻¹ to 0.091 S cm⁻¹, while the water uptake increased from 38% to 62%. Moreover, the SPEEK/SDBS membrane exhibited constant proton conductivity under a long-term water immersion test. Full article

(This article belongs to the Special Issue Conducting Polymers)

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17 pages, 9664 KiB

Open AccessArticle

Modified Carbon Fiber Paper-Based Electrodes Wrapped by Conducting Polymers with Enhanced Electrochemical Performance for Supercapacitors

by Sicong Tan, Jiajia Li, Lijie Zhou, Peng Chen, Jiangtao Shi and Zhaoyang Xu

Polymers 2018, 10(10), 1072; https://doi.org/10.3390/polym10101072 - 27 Sep 2018

Cited by 20 | Viewed by 6463

Abstract

An easy approach to fabricating carbon fiber paper (CFP) based electrodes has been developed. This method can be mainly divided into two steps, for which the mixture of cellulose nanofibers (CNFs) and carbon nanotubes (CNTs) was first deposited on the surface of carbon [...] Read more.

An easy approach to fabricating carbon fiber paper (CFP) based electrodes has been developed. This method can be mainly divided into two steps, for which the mixture of cellulose nanofibers (CNFs) and carbon nanotubes (CNTs) was first deposited on the surface of carbon fiber paper through a vacuum filtration device followed by immersing the hybrid paper into concentrated aniline solution to polymerize polyaniline (PANI). Compared to carbon fiber paper, the acid-treated carbon fiber paper (A-CFP)-based electrode provides more active sites, which are beneficial for the polymerization of polyaniline. The mixture of CNFs and CNTs could coat on the A-CFP by vacuum-filtration due to the high hydrophilicity of A-CFP improved by acid-treatment. PANI with different polymerization time was in-situ synthesized on the surface of the hybrid paper to form a three-dimensional cross-linked structure that greatly enhanced the electrochemical performance of the electrode by improving high capacitance, high rate-capability, and long cycle-life. Moreover, the assembled symmetrical supercapacitor showed a high area capacitance of 626 mF·cm⁻² and an energy density of 87 µWh·cm⁻². This facile, easy performed, and low-cost strategy may provide a feasible method for the production of supercapacitor electrodes. Full article

(This article belongs to the Special Issue Conducting Polymers)

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24 pages, 6071 KiB

Open AccessArticle

Investigation of the Effects of Non-Conjugated Co-Grafts on the Spectroelectrochemical and Photovoltaic Properties of Novel Conjugated Graft Copolymers Based on Poly(3-hexylthiophene)

by Tomasz Jarosz, Karolina Gebka, Kinga Kepska, Mieczyslaw Lapkowski, Przemyslaw Ledwon, Pawel Nitschke and Agnieszka Stolarczyk

Polymers 2018, 10(10), 1064; https://doi.org/10.3390/polym10101064 - 25 Sep 2018

Cited by 5 | Viewed by 3441

Abstract

A new type of polysiloxane copolymers, with conjugated–regioregular poly(3-hexylthiophene) (P3HT) and non-conjugated-poly(ethylene glycol) (PEG)-grafts have been synthesised, and their properties have been studied alongside those of the parent conjugated polymer (P3HT). Spectroelectrochemical and conductometric analyses revealed an early rise of the conductance of [...] Read more.

A new type of polysiloxane copolymers, with conjugated–regioregular poly(3-hexylthiophene) (P3HT) and non-conjugated-poly(ethylene glycol) (PEG)-grafts have been synthesised, and their properties have been studied alongside those of the parent conjugated polymer (P3HT). Spectroelectrochemical and conductometric analyses revealed an early rise of the conductance of the polymers. Once spectral changes begin taking place, the conductance is stable, implying a loss of mobility of charge carriers, even though standard doping/dedoping patterns are observed. Prototype bulk heterojunction solar cells have been fabricated, based on P3HT/[6,6]-Phenyl-C61-butyric acid methyl ester (PCBM), as well as by substituting P3HT for each of the copolymers. The prototype solar cells achieved PCEs of up to 2.11%. This is one of the highest reported power conversion efficiency (PCE) for devices based on P3HT with low average molecular weight M_n = 12 kDa. Strong correlation between the structure of the copolymer and its photovoltaic performance was found. Elongation of PEG copolymer chain and the use of methyl group instead of terminal hydroxyl groups significantly improved photovoltaic performance. Full article

(This article belongs to the Special Issue Conducting Polymers)

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10 pages, 2278 KiB

Open AccessPerspective

Graphene-Based Thermal Interface Materials: An Application-Oriented Perspective on Architecture Design

by Le Lv, Wen Dai, Aijun Li and Cheng-Te Lin

Polymers 2018, 10(11), 1201; https://doi.org/10.3390/polym10111201 - 27 Oct 2018

Cited by 45 | Viewed by 7744

Abstract

With the increasing power density of electrical and electronic devices, there has been an urgent demand for the development of thermal interface materials (TIMs) with high through-plane thermal conductivity for handling the issue of thermal management. Graphene exhibited significant potential for the development [...] Read more.

With the increasing power density of electrical and electronic devices, there has been an urgent demand for the development of thermal interface materials (TIMs) with high through-plane thermal conductivity for handling the issue of thermal management. Graphene exhibited significant potential for the development of TIMs, due to its ultra-high intrinsic thermal conductivity. In this perspective, we introduce three state-of-the-art graphene-based TIMs, including dispersed graphene/polymers, graphene framework/polymers and inorganic graphene-based monoliths. The advantages and limitations of them were discussed from an application point of view. In addition, possible strategies and future research directions in the development of high-performance graphene-based TIMs are also discussed. Full article

(This article belongs to the Special Issue Conducting Polymers)

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