Review
Materials Science, Multidisciplinary
Chirag R. Ratwani, Ali Reza Kamali, Amr M. Abdelkader
Summary: This review summarizes the recent advances in self-healing polymers based on reversible cycloaddition reactions, with a focus on the Diels-Alder (DA) reaction. The principles of the DA reaction and its application in polymers are introduced. The thermodynamics governing the rupture-repair process in self-healing polymers and the use of advanced spectroscopic techniques are discussed, along with their applicability in thermosets, epoxy resins, biopolymers, and polymer nanocomposites.
PROGRESS IN MATERIALS SCIENCE
(2023)
Article
Chemistry, Applied
Wan Zhao, Xiaotao Han, Yibin Lu, Zhiwen Zhang, Qiang Zhang, Pai Peng, Haitang Wu
Summary: This study proposes a novel strategy based on Diels-Alder bond for the fabrication of self-healing urushiol-based coatings with highly efficient self-healing performances and robust mechanical properties. By modifying natural urushiol and crosslinking it, a thermally reversible and self-healing bio-based coating is obtained. The ratio of urushiol furan derivative to bismaleimide is found to significantly affect the properties of the self-healing coatings. The optimized formulation results in a coating with high self-healing efficiency, hardness, and contact angle.
PROGRESS IN ORGANIC COATINGS
(2023)
Article
Engineering, Chemical
Bowen Xu, Feilong Han, Xuqiang Pei, Suojiang Zhang, Jingbo Zhao
Summary: This research proposed a new scheme for the industrial production of self-healing polyurethane and successfully synthesized a self-healing polyurethane using diacetyl oxime as the chain extender and triethanolamine as the cross-linking agent. The oxime urethanes in the polyurethane deblock efficiently at around 90 degrees C and re-block after the temperature is lowered, showing good self-healing properties.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2021)
Article
Materials Science, Multidisciplinary
Felipe Orozco, Mahsa Kaveh, Dian S. Santosa, Guilherme Macedo R. Lima, Diego Ribas Gomes, Yutao Pei, Rodrigo Araya-Hermosilla, Ignacio Moreno-Villoslada, Francesco Picchioni, Ranjita K. Bose
Summary: The conductive polyketone polymer and carbon nanotube composite discussed in the paper exhibit efficient electroactive shape memory effect and self-healing ability, making them suitable for soft robotics and actuators. These responsive polymers offer a step towards sustainable materials by extending product lifetime and reprocessability.
ACS APPLIED POLYMER MATERIALS
(2021)
Article
Chemistry, Organic
Jian-Xiang Zhu, Fu Pi, Teng Sun, Wen-Yu Huang, Lu Gao, Zhi-Chao Chen, Wei Du, Ying-Chun Chen
Summary: This article introduces a palladium-catalyzed tandem reaction that proceeds through sequential 2,4-dienylation/Michael addition/pi-sigma-pi isomerization/allylic alkylation. Using ortho-functionalized aryl enones and 2,4-dienyl carbonates as substrates, enantioenriched architectures with fused and spirocyclic frameworks are constructed in moderate to excellent yields and stereoselectivity. Importantly, the intrinsic intramolecular Diels-Alder reaction pattern of the dienylated intermediates is effectively reversed via Pd(0)-pi-Lewis base catalysis.
Article
Polymer Science
Ali Safaei, Joost Brancart, Zhanwei Wang, Sogol Yazdani, Bram Vanderborght, Guy Van Assche, Seppe Terryn
Summary: By adjusting the off-stoichiometric ratio of maleimide-to-furan in the polymer network, we demonstrate the ability of Diels-Alder polymers to heal macroscopic damages at room temperature and restore their mechanical properties within a few hours. Immediate partial recovery is observed mere minutes after reuniting the fractured surfaces. The influence of crosslink density on self-healing and material performance was investigated through an extensive study of seven different Diels-Alder polymers.
Article
Polymer Science
Paulina Bednarczyk, Karolina Mozelewska, Malgorzata Nowak, Joanna Klebeko, Joanna Rokicka, Paula Ossowicz-Rupniewska
Summary: The development of new photoreactive resins and the investigation of the relationship between phase structure and smart properties have attracted great interest. Different urethane acrylate resins with built-in DA structures and varying hard segment structures were prepared. Polymer films were cured using UV radiation and tested for various properties including photopolymerization kinetics, thermal characteristics, thermoreversibility performance, and self-healing ability.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Chemistry, Applied
Shalini Parihar, Bharti Gaur
Summary: This article reports on the development of two bio-based thermo-reversible polymers derived from gum rosin. The introduction of thermo-reversible linkages and Diels-Alder bonds improves the durability and self-healing capabilities of the material.
PROGRESS IN ORGANIC COATINGS
(2022)
Article
Materials Science, Composites
Xiaoqing Zhang, Sihui Liu, Zhuojian He, Caihong Lei
Summary: A thermally reversible sizing agent was prepared by mixing FAE and MAT for potential self-healing ability in carbon fiber composites. Surface characteristics of the modified carbon fibers were investigated, showing high healing efficiency in the first cycle. This strategy has potential to bring interface self-healing in carbon fiber composites from research to industrial applications.
POLYMER COMPOSITES
(2021)
Article
Polymer Science
Makoto Katoh, Mitsuhiro Shibata
Summary: This study investigates the polymer networks containing both Diels-Alder (DA) adduct moieties and disulfide bonds through the DA and thiol-maleimide reactions at various feed monomer ratios. The cured products exhibit the occurrence of DA and thiol-maleimide reactions, and self-healing abilities.
Article
Engineering, Chemical
Shiyang Zhang, Zelong Xu, Yatao Weng, Mingwei Cai, Yali Wang, Wenju Zhu, Yonggang Min, Xiaohua Ma
Summary: A high performance thermally rearranged polymer (EBAP-TR) membrane with high permeability, selectivity, mechanical strength and reliability has been reported. The membrane was formed by cross-linking and thermally rearranging a novel ortho-hydroxyl functionalized polyimide (EBAP-OH). The resulting EBAP-TR membrane exhibits remarkable CO2 permeability (6455 Barrer) and CO2/CH4 selectivity (40), outperforming the newest 2019 CO2/CH4 trade offline.
JOURNAL OF MEMBRANE SCIENCE
(2023)
Article
Polymer Science
Alexis Morinval, Luc Averous
Summary: This study developed a thermally responsive network based on reversible Diels-Alder reaction, by chemically modifying AMS and PBAT. It successfully addressed the incompatibility between the two materials, offering potential for developing high-performance materials in the circular bioeconomy.
EUROPEAN POLYMER JOURNAL
(2023)
Article
Chemistry, Physical
Eugenio Amendola, Barbara Palmieri, Stefania Dello Iacono, Alfonso Martone
Summary: In this study, the possibility of using a self-healing epoxy as an organic coating for metallic substrates was investigated. The recovery performance of the epoxy was evaluated through morphological observation, spectroscopic analysis, and mechanical and nanoindentation tests. The barrier properties and anti-corrosion performance were assessed through electrochemical impedance spectroscopy (EIS). The results showed that the coating could be repaired and restored its original properties after proper thermal treatment, indicating promising applications in the field of corrosion-resistant protective coatings and adhesives.
Article
Polymer Science
Yubin Li, Zhijian Yang, Xu Zhao, Jianhu Zhang, Ling Ding, Liping Pan, Congmei Lin, Xue Zheng
Summary: A novel thermally mendable polyurethane binder was synthesized through Diels-Alder cycloaddition reaction, showing good self-healing ability and the capability to repair microcracks efficiently in energetic composites.
POLYMERS FOR ADVANCED TECHNOLOGIES
(2021)
Article
Nanoscience & Nanotechnology
Sungmin Jung, Han Gyeol Jang, Jun Young Jo, Yoon Sang Kim, Doh C. Lee, Jaewoo Kim
Summary: Smart polymer materials with damage-detection and self-healing functionalities are developed by incorporating spiropyran (SP) beads into a Diels-Alder (DA) matrix. The dual functionality is highly dependent on the proportion of polyurethane (PU), with the best performance achieved at 40 wt% PU. A high healing efficiency of 96% is achieved via a dynamic DA reaction, and the dual-functionality remains repeatable after 10 cycles with a slight reduction in detection and healing efficiencies.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Polymer Science
Lisa Ehrlich, Doris Pospiech, Upenyu L. Muza, Albena Lederer, Julia Muche, Dieter Fischer, Petra Uhlmann, Felix Tzschoeckell, Simon Muench, Martin D. Hager, Ulrich S. Schubert
Summary: This study investigates solid electrolytes based on ionic liquid polymers that offer stable ion conduction. Ionic liquid monomers are converted into linear homopolymers or polymer networks by thermally initiated radical polymerization or UV-initiated copolymerization. The materials are confirmed through NMR or Raman spectroscopy, and their ionic conductivities are measured. The results show that these materials have potential as electrolytes for solid-state batteries.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2023)
Article
Chemistry, Analytical
Ekaterina Tsarenko, Ulrich S. Schubert, Ivo Nischang
Summary: Multifunctional nanoparticle formulations for medical purposes have been successfully developed, with a persistent challenge being the quantitative compositional analysis of the NPs with the polymer matrix and encapsulated drugs. In this study, PLGA NPs were formulated and their integrity and size were analyzed using DLS and SEM. Liquid chromatography on reversed-phase silica monolithic columns was used to quantitatively assess the amount of small molecule drugs and NP constituting PLGA polymer. The study demonstrates the viability of reversed-phase monolithic silica in chromatography, providing a valuable strategy for analysis of various precursor polymer systems and drug components in multifunctional drug formulations.
ANALYTICAL CHEMISTRY
(2023)
Article
Chemistry, Physical
Erik Schroeter, Lada Elbinger, Manon Mignon, Christian Friebe, Johannes C. Brendel, Martin D. Hager, Ulrich S. Schubert
Summary: Aqueous zinc batteries with organic cathode materials have the potential to be sustainable, safe, environmentally friendly, and highly flexible secondary energy storage systems. In this study, we demonstrate the preparation of an oxygen-tolerant, semi-organic setup using an all-aqueous process, from polymerization to coin cell assembly, without the need for intermediate purification steps. The resulting battery exhibits high energy densities and excellent stability, making it a promising candidate for cost-effective and efficient rechargeable zinc-based batteries.
JOURNAL OF POWER SOURCES
(2023)
Article
Polymer Science
Nicole Ziegenbalg, Hans F. F. Ulrich, Steffi Stumpf, Philipp Mueller, Jurgen Wiethan, Janette Danner, Ulrich S. S. Schubert, Torben Adermann, Johannes C. C. Brendel
Summary: This study investigated the polymerization of VME monomer in water and found that the resulting polymer could coordinate with silver or gold ions, forming stable dispersions. Polyvinyl alcohol (PVA) was identified as the only surfactant capable of creating stable dispersions. Exposure to sunlight led to controlled reduction of the metal ions and the formation of composite particles. Silver ion-containing dispersions demonstrated strong antibacterial properties.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2023)
Article
Polymer Science
Natalie E. Goeppert, Michael Dirauf, Phil Liebing, Christine Weber, Ulrich S. Schubert
Summary: A monomer of 3-benzylmorpholine-2,5-dione is synthesized from l-phenylalanine and characterized by various techniques. A well-defined poly(ester amide) homopolymer is then synthesized using a binary catalyst system, showing high controllability of dispersities and molar masses. The resulting polyesteramides have potential as drug delivery vehicles, especially for hydrophobic drugs.
MACROMOLECULAR RAPID COMMUNICATIONS
(2023)
Article
Materials Science, Multidisciplinary
Zehan Chen, He Jia, Stephanie Hoeppener, Christian Friebe, Jiande Wang, Geraldine Chanteux, Dongjiu Xie, Yan Lu, Alexandru Vlad, Ulrich S. Schubert, Jean-Francois Gohy
Summary: We develop hollow porous silicon nanospheres with a three-dimensional carbon coating and SiC transition interlayer (C@SiC@Si@SiC@C) to address the challenges faced by Si anodes. The synthesized C@SiC@Si@SiC@C anode shows high utilization of the active substance, high measured capacity (3200 mAh g-1), and stable cycling performance (0.7% per cycle decay rate at 0.2C). The superior performances are attributed to the unique structure design and the functional features of carbon coating and SiC transition interlayer.
MATERIALS & DESIGN
(2023)
Review
Materials Science, Multidisciplinary
Maryam Moradi, Michael Jaeger, George R. Newkome, Ulrich S. Schubert
Summary: Plasmon-triggered modulation of fluorophores' photoluminescence brings tremendous opportunities for various applications. The distance between plasmonic components and fluorophores is crucial in plasmon-exciton coupling and the overall optical characteristics of the fluorophores. Developing novel hybrid systems with active tuning of optical properties is in high demand, and incorporating responsive materials like liquid crystals and stimuli-responsive polymers as a separating layer can achieve this.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Nanoscience & Nanotechnology
He Jia, Zehan Chen, Shanshan Yan, Fabio Lucaccioni, Zdravko Kochovski, Yan Lu, Christian Friebe, Ulrich S. Schubert, Jean-Francois Gohy
Summary: Nanoreactors with hydrophilic porous SiO2 shells and amphiphilic copolymer cores were prepared, which can adjust their hydrophilic/hydrophobic balance and exhibit chameleon-like behavior depending on the environment. The resulting nanoparticles showed excellent colloidal stability in solvents with different polarities. Importantly, with the help of nitroxide radicals attached to the amphiphilic copolymers, the synthesized nanoreactors exhibited high catalytic activity in both polar and nonpolar environments, and achieved high selectivity for the products of benzyl alcohol oxidation in toluene.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Multidisciplinary
Patrick Endres, Timo Schuett, Julian Kimmig, Stefan Zechel, Martin D. Hager, Robert Geitner, Ulrich S. Schubert
Summary: In this study, online NMR measurements are introduced as a new analytical setup for investigating the synthesis of oxymethylene dimethyl ether (OME). The setup is validated by comparing it with state-of-the-art gas chromatographic analysis. The influence of parameters such as temperature, catalyst concentration, and catalyst type on OME fuel formation based on trioxane and dimethoxymethane is investigated, with Amberlyst(TM) 15 (A15) and trifluoromethanesulfonic acid (TfOH) being used as catalysts. A kinetic model is applied to describe the reaction and calculate the activation energy and catalyst order.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Erik Schroeter, Christian Stolze, Jakob Meyer, Martin D. Hager, Ulrich S. Schubert
Summary: The hydrophilic polymer PTMAm was used as a redox target material in an aqueous organic redox targeting flow battery. The polymer was processed into granules with a conductive agent and an alginate binder to obtain a hydrophilic, water-insoluble redox target. The redox target was combined with the redox mediator molecule TEMPOAmide, and electrochemical characterization and flow battery testing were conducted. In addition, in-situ characterization of the redox target was performed for the first time, providing estimates of its state-of-charge changes during cycling. A figure of merit, redox targetivity, was proposed to evaluate the efficiency of the targeting reaction and guide future optimization of materials, cell designs, and operational parameters for RTFBs.
Article
Energy & Fuels
Aurelien Sokeng Djoumessi, Anastasia Sichwardt, Daria Miliaieva, Jan Cermak, Maximilian Schaal, Felix Otto, Stepan Stehlik, Jaroslav Kulicek, Vojtech Nadazdy, Torsten Fritz, Alexander Kromka, Bohuslav Rezek, Ulrich S. S. Schubert, Harald Hoppe
Summary: Diamond nanoparticles, also known as nanodiamonds, have attracted scientific interest due to their optical and electronic properties, nontoxicity, biocompatibility, and large surface area. The versatility of the surface chemistry of nanodiamonds allows for the attachment of various functional groups, providing a platform for adjusting their properties and functions. In this study, high-pressure high-temperature nanodiamonds were tested as charge extraction material in organic solar cells, and hydrogenated nanodiamonds were found to be effective for electron extraction.
Article
Chemistry, Physical
Thomas Wloka, Steffen Czich, Franziska Chalupa-Gantner, Maria Sittig, Michael Dirauf, Christine Weber, Michael Gottschaldt, Klaus Liefeith, Aleksandr Ovsianikov, Benjamin Dietzek-Ivansic, Ulrich S. Schubert
Summary: Hydrogels, widely used in biomedical applications, also show great potential in other fields such as lens fabrication and electronics. The technique of two-photon polymerization (2PP) is effective in processing hydrogels due to its high spatio-temporal resolution. This study synthesized water-soluble two-photon photo-initiators (2PIs) based on benzyli-dene cyclopentanone structures, and evaluated their efficiency and cytotoxicity for 2PP. The results showed that several 2PIs exhibited low cytotoxicity and good initiation efficiency, making them suitable for 3D structuring of hydrogels.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Julian Hniopek, Josefine Meurer, Stefan Zechel, Michael Schmitt, Martin D. Hager, Juergen Popp
Summary: Stimuli-responsive polymers can switch specific physical properties in response to a change of the environmental conditions, making them useful for applications requiring adaptive materials. A straightforward method using Raman micro-spectroscopy and 2DCOS analysis is presented to study the response behavior of reversible polymers on a molecular level with molecular sensitivity and spatial as well as temporal resolution. This label-free and non-invasive approach allows for the investigation of macroscopic properties alongside the molecular response of the polymer to external stimuli.
Article
Polymer Science
Yuanzhang Jiang, Xuyi Wang, Yanting Han, Dakai Gong, Yingchun Gu, Lin Tan
Summary: In this study, FeCl3 and poly(acrylic acid) (PAA) were doped into waterborne polyurethanes (WPUs) to create multifunctional materials with self-healing and antimicrobial properties. WPU/Fe/PAA-5.5, containing 5.5 wt % PAA, exhibited excellent mechanical properties, strong self-healing capabilities, and an impressive antimicrobial rate of over 90%. These supramolecular films were also highly recyclable through hot-pressing.
Article
Polymer Science
Longyu Tian, Min Wang, Guangming Liao, Baoliang Liu, Sujuan Zhang, Yucheng Sun, Zhen Meng, Jintao Zhang, Zaijun Lu
Summary: Two kinds of benzoxazine monomers were synthesized and used to prepare polybenzoxazine anion exchange membranes (AEMs) with quaternary ammonium functionalization. The LQPBZ AEM exhibited better ion conductivity and alkaline stability.
Article
Polymer Science
Claire A. Lemarchand
Summary: This study investigates the shock behavior of three different polymers through molecular dynamics simulations. The results reveal specificities in the shock behavior of polymers, including deviations from the linear relation between shock velocity and particle velocity, as well as differences in shear stress relaxation behind the shock front. It is found that the deviation of the Hugoniot locus is related to the change in the relative contribution of bonding and non-bonding potential energies, while polymers with higher glass transition temperatures exhibit slower shear stress relaxation.
Article
Polymer Science
Zengquan Liu, Xiaochun Yin, He Zhang, Shuo Gao, Qinglin Kuang, Yanhong Feng
Summary: A powder solid-state extension (PSSE) technology was proposed to address the high melt viscosity issue of UHMWPE. By uniaxial extension and sintering in the solid state, a highly self-reinforced material was prepared. X-ray diffraction and scattering techniques were used to study the structural evolution during the PSSE process, and a solid-phase induced transformation model was established.
Article
Polymer Science
Zhike Li, Anyu Luo, Rui Zhou, Xin Li, Haiyan Li
Summary: A novel high temperature resistance IL@SiO2 nanocapsules were successfully prepared and their friction and wear properties in PA6 composites were studied. The addition of IL@SiO2 nanocapsules reduced the friction coefficient and wear rate without affecting the mechanical properties of PA6. The synergy between the IL core and SiO2 wall in the nanocapsules improved the self-lubricating performance of the PA6 composites.
Article
Polymer Science
Xin Liu, Xuhong Guo, Qi Liao
Summary: In this study, an algorithm for accurately estimating viscosity is developed using molecular dynamics simulations and the Green-Kubo formula. This algorithm can be applied to complex systems with long correlations, such as macromolecular and biological simulation systems.
Article
Polymer Science
Hao Pu, Yun-Lei Hou, Jing -Zhou Chen, Dong -Lin Zhao
Summary: The use of modified graphene improves the interfacial adherence of carbon fibers to epoxy resin, resulting in enhanced interfacial and bending properties of CF and matrix in CF/EP composites, as well as increased interlaminar shear strength and flexural strength.
Article
Polymer Science
Wei-Chung Ke, Jin-Wei Lin, Manohar Reddy Busireddy, Yueh-Hsing Lee, Jiun-Tai Chen, Chain-Shu Hsu
Summary: This study introduces a crosslinkable monomer, TAIC, to synthesize three crosslinked polyimide films, which exhibit improved thermal, mechanical, and dielectric properties. The introduction of TAIC enhances the tensile strength, reduces the dielectric constant and dielectric loss, and decreases the coefficient of thermal expansion of the polyimide films.
Article
Polymer Science
Alex Kwasi Kumi, Ruiling Fan, Ye Chen, Yumei Zhang
Summary: The difference in leaching of amylopectin from cellulose/amylopectin/1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) blends during regeneration in water and aqueous ethanol has been studied. Molecular dynamics simulations showed that the dissolution and regeneration mechanisms of amylopectin in [Bmim][Cl] are similar to cellulose in ionic liquids. Water regeneration leads to weak electrostatic interactions, resulting in high leaching of amylopectin. In contrast, ethanol-water interactions enhance electrostatic interactions among amylopectin chains, limiting amylopectin leaching in aqueous ethanol.
Article
Polymer Science
Xi Zeng, Junwei Zhou, Junbiao Peng, Chunsheng Zhang, Danling Wang, Yihu Song, Qiang Zheng
Summary: This study utilizes an oligomer deep eutectic solvent (DES) based on polyethylene glycol to regulate the vulcanization kinetics of rubber. The results show that the DES can accelerate vulcanization at low temperatures without affecting the crosslinking density and Mullins effect.
Article
Polymer Science
Qianqian Yue, Yongfei Peng, Xingjian Liu, Aihua He, Huarong Nie
Summary: The addition of metal deactivators can effectively suppress the aging of TBIR, prolong its lifespan, and have no negative effects on its physical and processing properties. These research findings are of great importance for improving the stability and aging resistance of polymers.
Article
Polymer Science
J. Gomez-Caturla, J. Ivorra-Martinez, R. Tejada-Oliveros, V Moreno, D. Garcia-Garcia, R. Balart
Summary: This work focuses on the development of environmentally friendly PLA formulations by using different esters derived from geraniol as plasticizers. The results show that these esters have good compatibility with PLA, and they can effectively enhance the elongation and plasticity of PLA, reduce its glass transition temperature, and slightly improve its water absorption capabilities.
Article
Polymer Science
Dandan Li, Zhaohui Lu, Zhao Ke, Ke Xu, Fengna Dai, Youhai Yu, Guangtao Qian, Chunhai Chen
Summary: In this study, cross-linked PI aerogel membranes with low dielectric constant and high moisture resistance were prepared by co-polymerization and scraping coating technology. The incorporation of fluorinated blocks and benzimidazole ring structures resulted in novel PI aerogel membranes with fascinating dielectric properties and outstanding moisture resistance.
Article
Polymer Science
Zhaoyang Chu, Qing Zhang, Haihua Luo, Han Zhou, Fapei Zhang, Wei Chen, Wenhua Zhang
Summary: Multi-physical fields solution processing strategy is a universal and facile method for preparing various conjugated polymer films and high-performance devices. In this study, we employed a combined microfluidic flow and ultrasonication strategy (FU) for processing CP solutions, and found a pronounced synergetic effect in promoting the pre-ordering of chains in solution. The conformation order and anisotropy of the solution were revealed through various characterizations. A non-classical nucleation model for polymer crystallization in non-equilibrium solution processing was confirmed. The roles of microfluidic flow and ultrasonication in chain aggregation and crystallization were addressed through multi-physical simulations. Compared to pristine solutions, the FU strategy showed improved solution anisotropy and crystallization kinetics, resulting in higher crystallinity in films and increased mobilities in OFET devices. The FU processing strategy provides a universal approach for regulating chain conformation and aggregation in conjugated polymer solutions.
