Showing papers on "Polymer published in 2013"
TL;DR: In this paper, the surface of inorganic nanoparticles is modified to improve the interfacial interactions between the inorganic particles and the polymer matrix, which improves the properties of polymeric composites.
1,709 citations
TL;DR: The most promising nanoscale fillers are layered silicate nanoclays such as montmorillonite and kaolinite as mentioned in this paper, which can provide active and/or smart properties to food packaging systems.
1,461 citations
TL;DR: CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration and have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage.
Abstract: Conjugated microporous polymers (CMPs) are a class of organic porous polymers that combine π-conjugated skeletons with permanent nanopores, in sharp contrast to other porous materials that are not π-conjugated and with conventional conjugated polymers that are nonporous. As an emerging material platform, CMPs offer a high flexibility for the molecular design of conjugated skeletons and nanopores. Various chemical reactions, building blocks and synthetic methods have been developed and a broad variety of CMPs with different structures and specific properties have been synthesized, driving the rapid growth of the field. CMPs are unique in that they allow the complementary utilization of π-conjugated skeletons and nanopores for functional exploration; they have shown great potential for challenging energy and environmental issues, as exemplified by their excellent performance in gas adsorption, heterogeneous catalysis, light emitting, light harvesting and electrical energy storage. This review describes the molecular design principles of CMPs, advancements in synthetic and structural studies and the frontiers of functional exploration and potential applications.
1,335 citations
TL;DR: Infiltration of a conducting polymer hydrogel into Si-based anodes results in a well-connected three-dimensional network structure consisting of Si nanoparticles conformally coated by the conducting polymer, demonstrating a cycle life of 5,000 cycles with over 90% capacity retention at current density.
Abstract: Silicon has a high-specific capacity as an anode material for Li-ion batteries, and much research has been focused on overcoming the poor cycling stability issue associated with its large volume changes during charging and discharging processes, mostly through nanostructured material design. Here we report incorporation of a conducting polymer hydrogel into Si-based anodes: the hydrogel is polymerized in-situ, resulting in a well-connected three-dimensional network structure consisting of Si nanoparticles conformally coated by the conducting polymer. Such a hierarchical hydrogel framework combines multiple advantageous features, including a continuous electrically conductive polyaniline network, binding with the Si surface through either the crosslinker hydrogen bonding with phytic acid or electrostatic interaction with the positively charged polymer, and porous space for volume expansion of Si particles. With this anode, we demonstrate a cycle life of 5,000 cycles with over 90% capacity retention at current density of 6.0 A g(-1).
1,181 citations
TL;DR: The state of the art in the field of antimicrobial polymeric systems during the last decade is described in this paper, where a classification of the different materials is carried out dividing basically those synthetic polymers that exhibit antimicrobial activity by themselves; those whose biocidal activity is conferred through their chemical modification; those that incorporate antimicrobial organic compounds with either low or high molecular weight; and those that involve the addition of active inorganic systems.
1,063 citations
TL;DR: This work reviews the progress that has been made in making sequence-controlled polymers of increasing length and complexity and proposes some strategies for controlling sequences in chain-growth and step-growth polymerizations.
Abstract: Background During the last few decades, progress has been made in manipulating the architecture of synthetic polymer materials. However, the primary structure—that is, the sequential arrangement of monomer units in a polymer chain—is generally poorly controlled in synthetic macromolecules. Common synthetic polymers are usually homopolymers, made of the same monomer unit, or copolymers with simple chain microstructures, such as random or block copolymers. These polymers are used in many areas but do not have the structural and functional complexity of sequence-defined biopolymers, such as nucleic acids or proteins. Indeed, monomer sequence regulation plays a key role in biology and is a prerequisite for crucial features of life, such as heredity, self-replication, complex self-assembly, and molecular recognition. In this context, developing synthetic polymers containing controlled monomer sequences is an important area for research. Precise molecular encoding of synthetic polymer chains. In most synthetic copolymers, monomer units (represented here as colored square boxes A, B, C, and D) are distributed randomly along the polymer chains (left). In sequence-controlled polymers, they are arranged in a specific order in all of the chains (right). Monomer sequence regularity strongly influences the molecular, supramolecular, andmacroscopic properties of polymer materials. Advances Various synthetic methods for controlling monomer sequences in polymers have been identified, and two major trends in the field of sequence-controlled polymers have emerged. Some approaches use biological concepts that have been optimized by nature for sequence regulation. For instance, DNA templates, enzymes, or even living organisms can be used to prepare sequence-defined polymers. These natural mechanisms can be adapted to tolerate nonnatural monomers. The other trend is the preparation of sequence-controlled polymers by synthetic chemistry. In the most popular approach, monomer units are attached one by one to a support, which is an efficient method but demanding in practice. Recently, some strategies have been proposed for controlling sequences in chain-growth and step-growth polymerizations. These mechanisms usually allow fast and large-scale synthesis of polymers. Specific kinetics and particular catalytic or template conditions allow sequence regulation in these processes. Outlook The possibility of controlling monomer sequences in synthetic macromolecules has many scientific and technological implications. Information can be controlled at the molecular level in synthetic polymer chains. This opens up interesting perspectives for the field of data storage. In addition, having power over monomer sequences could mean structural control of the resulting polymer, as it strongly influences macromolecular folding and self-assembly. For instance, functional synthetic assemblies that mimic the properties of globular proteins, such as enzymes and transporters, can be foreseen. Moreover, monomer sequence control influences some macroscopic properties. For example, bulk properties such as conductivity, rigidity, elasticity, or biodegradability can be finely tuned in sequence-controlled polymers. The behavior of polymers in solution, particularly in water, is also strongly dependent on monomer sequences. Thus, sequence regulation may enable a more effective control of structure-property relations in tomorrow’s polymer materials.
1,008 citations
TL;DR: The main achievements in nitroxide-mediated polymerization (NMP) from its discovery to late 2010 are discussed in this paper, where various synthetic approaches to nitroxides and alkoxyamines are first presented.
987 citations
TL;DR: A shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.
Abstract: Microporous polymers of extreme rigidity are required for gas-separation membranes that combine high permeability with selectivity. We report a shape-persistent ladder polymer consisting of benzene rings fused together by inflexible bridged bicyclic units. The polymer’s contorted shape ensures both microporosity—with an internal surface area greater than 1000 square meters per gram—and solubility so that it is readily cast from solution into robust films. These films demonstrate exceptional performance as molecular sieves with high gas permeabilities and good selectivities for smaller gas molecules, such as hydrogen and oxygen, over larger molecules, such as nitrogen and methane. Hence, this polymer has excellent potential for making membranes suitable for large-scale gas separations of commercial and environmental relevance.
834 citations
TL;DR: This present review wants to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.
Abstract: Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.
827 citations
TL;DR: In this article, a stretchable polymer LED is fabricated that is capable of emitting light when subjected to strains as large as 120% and a prototype 5 × 5 pixel monochrome display based on an array of these LEDs is demonstrated.
Abstract: A stretchable polymer LED is fabricated that is capable of emitting light when subjected to strains as large as 120%. A prototype 5 × 5 pixel monochrome display based on an array of these LEDs is demonstrated.
826 citations
TL;DR: Almost all synthetic polymers require stabilization against adverse environmental effects, and two aspects of degradation are of particular importance: Storage conditions, and Addition of appropriate stabilizers.
Abstract: Exposure to ultraviolet (UV) radiation may cause the significant degradation of many materials. UV radiation causes photooxidative degradation which results in breaking of the polymer chains, produces free radical and reduces the molecular weight, causing deterioration of mechanical properties and leading to useless materials, after an unpredictable time. Polystyrene (PS), one of the most important material in the modern plastic industry, has been used all over the world, due to its excellent physical properties and low-cost. When polystyrene is subjected to UV irradiation in the presence of air, it undergoes a rapid yellowing and a gradual embrittlement. The mechanism of PS photolysis in the solid state (film) depends on the mobility of free radicals in the polymer matrix and their bimolecular recombination. Free hydrogen radicals diffuse very easily through the polymer matrix and combine in pairs or abstract hydrogen atoms from polymer molecule. Phenyl radical has limited mobility. They may abstract hydrogen from the near surrounding or combine with a polymer radical or with hydrogen radicals. Almost all synthetic polymers require stabilization against adverse environmental effects. It is necessary to find a means to reduce or prevent damage induced by environmental components such as heat, light or oxygen. The photostabilization of polymers may be achieved in many ways. The following stabilizing systems have been developed, which depend on the action of stabilizer: (1) light screeners, (2) UV absorbers, (3) excited-state quenchers, (4) peroxide decomposers, and (5) free radical scavengers; of these, it is generally believed that excited-state quenchers, peroxide decomposers, and free radical scavengers are the most effective. Research into degradation and ageing of polymers is extremely intensive and new materials are being synthesized with a pre-programmed lifetime. New stabilizers are becoming commercially available although their modes of action are sometimes not thoroughly elucidated. They target the many possible ways of polymer degradation: thermolysis, thermooxidation, photolysis, photooxidation, radiolysis etc. With the goal to increase lifetime of a particular polymeric material, two aspects of degradation are of particular importance: Storage conditions, and Addition of appropriate stabilizers. A profound knowledge of degradation mechanisms is needed to achieve the goal.
TL;DR: This Review describes successful 2D polymerization strategies, as well as seminal research that inspired their development, and describes the early application targets of 2D polymers, each of which might benefit from predictable long-range molecular organization inherent to this macromolecular architecture.
Abstract: Two-dimensional polymers, which exhibit periodic bonding in two orthogonal directions, offer mechanical, electronic and structural properties distinct from their linear or irregularly crosslinked polymer counterparts. Their potential is largely unexplored because versatile and controlled synthetic strategies are only now emerging. This Review describes recent developments in two-dimensional polymerization methods.
TL;DR: In this paper, trathin sheets of polymer LEDs that emit light even when being crumpled or stretched have been realized, and they could prove useful for integration with textiles.
Abstract: Ultrathin sheets of polymer LEDs that emit light even when being crumpled or stretched have been realized The 2-μm-thick devices emit red or orange light with a sufficiently high brightness for indoor applications, and they could prove useful for integration with textiles
TL;DR: This progress report summarizes the numerous DPP-containing polymers recently developed for field-effect transistor applications including diphenyl-DPP and dithienyl- DPP-based polymers as the most commonly reported materials and highlights fundamental structure-property relations such as the relationships between the thin film morphologies and the charge carrier mobilities observed for D PP- containing polymers.
Abstract: This progress report summarizes the numerous DPP-containing polymers recently developed for field-effect transistor applications including diphenyl-DPP and dithienyl-DPP-based polymers as the most commonly reported materials, but also difuranyl-DPP, diselenophenyl-DPP and dithienothienyl-DPP-containing polymers. We discuss the hole and electron mobilities that were reported in relation to structural properties such as alkyl substitution patterns, polymer molecular weights and solid state packing, as well as electronic properties including HOMO and LUMO energy levels. We moreover consider important aspects of ambipolar charge transport and highlight fundamental structure-property relations such as the relationships between the thin film morphologies and the charge carrier mobilities observed for DPP-containing polymers.
Book•
03 Mar 2013
TL;DR: In this article, the authors discuss the role of molecular as well as fracture mechanics and shear yielding in collision and fatigue in a multiphase polyamide-polyamide (MPP) system.
Abstract: 1 Introduction.- I-Mechanics and Mechanisms.- 2 Molecular Aspects.- 3 Fracture Mechanics.- 4 Shear Yielding.- 5 Crazing.- 6 Impact and Fatigue.- II-Materials.- 7 Glassy Polymers I-Thermoplastics.- 8 Glassy Polymers II-Thermosets.- 9 Crystalline Polymers.- 10 Rubbers.- 11 Toughened Multiphase Plastics.- Author Index.
TL;DR: Compared with its sulfur–polyaniline core–shell counterparts, the yolk–shell nanostructures delivered much improved cyclability owing to the presence of internal void space inside the polymer shell to accommodate the volume expansion of sulfur during lithiation.
Abstract: Lithium–sulfur batteries have attracted much attention in recent years due to their high theoretical capacity of 1672 mAh g–1 and low cost However, a rapid capacity fade is normally observed, attributed mainly to polysulfide dissolution and volume expansion Although many strategies have been reported to prolong the cyclability, the high cost and complex preparation processes still hinder their practical application Here, we report the synthesis of a polyaniline–sulfur yolk–shell nanocomposite through a heating vulcanization of a polyaniline–sulfur core–shell structure We observed that this heating treatment was much more effective than chemical leaching to prepare uniform yolk–shell structures Compared with its sulfur–polyaniline core–shell counterparts, the yolk–shell nanostructures delivered much improved cyclability owing to the presence of internal void space inside the polymer shell to accommodate the volume expansion of sulfur during lithiation The yolk–shell material exhibited a stable capaci
TL;DR: From this observation emerged a versatile and comprehensive approach to surface modification of a variety of solid, porous, and nanoparticulate substrates composed of metals, ceramics, and polymers.
Abstract: Polyphenolic compounds present in tea, red wine, and chocolate form thin adherent polyphenol films on substrates through spontaneous adsorption from solution. From this observation emerged a versatile and comprehensive approach to surface modification of a variety of solid, porous, and nanoparticulate substrates composed of metals, ceramics, and polymers (see picture; ROS=reactive oxygen species).
TL;DR: The cobalt-coordinated conjugated microporous polymers can also simultaneously function as heterogeneous catalysts for the reaction of CO2 and propylene oxide at atmospheric pressure and room temperature, wherein the polymers demonstrate better efficiency than a homogeneous salen-cobalt catalyst.
Abstract: Conjugated microporous polymers are a new class of porous materials with an extended π-conjugation in an amorphous organic framework. Owing to the wide-ranging flexibility in the choice and design of components and the available control of pore parameters, these polymers can be tailored for use in various applications, such as gas storage, electronics and catalysis. Here we report a class of cobalt/aluminium-coordinated conjugated microporous polymers that exhibit outstanding CO2 capture and conversion performance at atmospheric pressure and room temperature. These polymers can store CO2 with adsorption capacities comparable to metal-organic frameworks. The cobalt-coordinated conjugated microporous polymers can also simultaneously function as heterogeneous catalysts for the reaction of CO2 and propylene oxide at atmospheric pressure and room temperature, wherein the polymers demonstrate better efficiency than a homogeneous salen-cobalt catalyst. By combining the functions of gas storage and catalysts, this strategy provides a direction for cost-effective CO2 reduction processes.
TL;DR: A novel approach is presented to disperse non-oxidized graphene flakes with non-covalent functionalization of 1-pyrenebutyric acid and to fabricate nanocomposites with outstanding thermal conductivity and mechanical properties.
Abstract: Homogeneous distribution of graphene flakes in a polymer matrix, still preserving intrinsic material properties, is key to successful composite applications. A novel approach is presented to disperse non-oxidized graphene flakes with non-covalent functionalization of 1-pyrenebutyric acid and to fabricate nanocomposites with outstanding thermal conductivity (∼1.53 W/mK) and mechanical properties (∼1.03 GPa).
TL;DR: In this article, a review summarizes recent advances in the hydrolysis of cellulose by different types of solid acids, such as sulfonated carbonaceous based acids, polymer based acids and magnetic solid acids.
TL;DR: The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery.
Abstract: The demand for efficient utilization of biomass induces a detailed analysis of the fundamental chemical structures of biomass, especially the complex structures of lignin polymers, which have long been recognized for their negative impact on biorefinery. Traditionally, it has been attempted to reveal the complicated and heterogeneous structure of lignin by a series of chemical analyses, such as thioacidolysis (TA), nitrobenzene oxidation (NBO), and derivatization followed by reductive cleavage (DFRC). Recent advances in nuclear magnetic resonance (NMR) technology undoubtedly have made solution-state NMR become the most widely used technique in structural characterization of lignin due to its versatility in illustrating structural features and structural transformations of lignin polymers. As one of the most promising diagnostic tools, NMR provides unambiguous evidence for specific structures as well as quantitative structural information. The recent advances in two-dimensional solution-state NMR techniques for structural analysis of lignin in isolated and whole cell wall states (insitu), as well as their applications are reviewed.
TL;DR: The authors have proposed for the first time an overview of all chemical grafting strategies used to date on nanofibrillated cellulose with focus on surface modification such as physical adsorption, molecular grafting or polymer grafting.
Abstract: Interest in nanofibrillated cellulose (NFC) has increased notably over recent decades. This bio-based nanomaterial has been used essentially in bionanocomposites or in paper thanks to its high mechanical reinforcement ability or barrier property respectively. Its nano-scale dimensions and its capacity to form a strong entangled nanoporous network have encouraged the emergence of new high-value applications. It is worth noting that chemical surface modification of this material can be a key factor to achieve a better compatibility with matrices. In order to increase the compatibility in different matrices or to add new functions, surface chemical modification of NFC appears to be the prior choice to conserve its intrinsic nanofibre properties. In this review, the authors have proposed for the first time an overview of all chemical grafting strategies used to date on nanofibrillated cellulose with focus on surface modification such as physical adsorption, molecular grafting or polymer grafting.
TL;DR: A protein was successfully enclosed within a hollow self-assembled spherical complex, with a long-term view towards the control of protein functions for the development of new applications.
TL;DR: In this paper, the authors highlight the functionalization chemistry of graphene with polymers by both covalent and non-covalent approaches and highlight the properties of these modified graphenes with an emphasis on different area where future developments are expected.
TL;DR: The results indicated that the C-16 alkyl side chain ionomer had a slightly better initial performance, despite its low IEC value, but very poor durability in the fuel cell.
Abstract: To produce an anion-conductive and durable polymer electrolyte for alkaline fuel cell applications, a series of quaternized poly(2,6-dimethyl phenylene oxide)s containing long alkyl side chains pendant to the nitrogen-centered cation were synthesized using a Menshutkin reaction to form comb-shaped structures The pendant alkyl chains were responsible for the development of highly conductive ionic domains, as confirmed by small-angle X-ray scattering (SAXS) The comb-shaped polymers having one alkyl side chain showed higher hydroxide conductivities than those with benzyltrimethyl ammonium moieties or structures with more than one alkyl side chain per cationic site The highest conductivity was observed for comb-shaped polymers with benzyldimethylhexadecyl ammonium cations The chemical stabilities of the comb-shaped membranes were evaluated under severe, accelerated-aging conditions, and degradation was observed by measuring IEC and ion conductivity changes during aging The comb-shaped membranes retained
TL;DR: Azo-bridged, nitrogen-rich, aromatic, water stable, nanoporous covalent organic polymers, which can be synthesized by catalyst-free direct coupling of aromatic nitro and amine moieties under basic conditions are reported, displaying an unprecedented increase in CO(2)/N(2) selectivity with increasing temperature.
Abstract: Porous materials are well studied for gas capture and separation technologies. Here, the authors report nitrogen-rich, nanoporous polymers, which display very high CO2/N2 selectivity with increasing temperature, which may be attributable to an entropically driven N2-phobicity effect.
TL;DR: Polymer tandem solar cells with 10.2% power conversion efficiency are demonstrated via stacking two PDTP-DFBT:PC₇₁ BM bulk heterojunctions, connected by MoO₃/PEDOT:PSS/ZnO as an interconnecting layer.
Abstract: Polymer tandem solar cells with 102% power conversion efficiency are demonstrated via stacking two PDTP-DFBT:PC₇₁ BM bulk heterojunctions, connected by MoO₃/PEDOT:PSS/ZnO as an interconnecting layer The tandem solar cells increase the power conversion efficiency of the PDTP-DFBT:PC₇₁ BM system from 81% to 102%, successfully demonstrating polymer tandem solar cells with identical sub-cells of double-digit efficiency
TL;DR: In this paper, a monomer approach for renewable polymers is presented, which is based on the assumption that natural molecular biomass plays an important role in the field of polymers and can be directly used or derivatized as monomers for controlled polymerization, in a way similar to many petroleum-derived monomers.
Abstract: Natural molecular biomass plays an important role in the field of renewable polymers, as they can be directly used or derivatized as monomers for controlled polymerization, in a way similar to many petroleum-derived monomers. We deliver this perspective primarily based on a monomer approach. Biomass-derived monomers are separated into four major categories according to their natural resource origins: (1) oxygen-rich monomers including carboxylic acids (lactic acid, succinic acid, itaconic acid, and levulinic acid) and furan; (2) hydrocarbon-rich monomers including vegetable oils, fatty acids, terpenes, terpenoids and resin acids; (3) hydrocarbon monomers (bio-olefins); and (4) non-hydrocarbon monomers (carbon dioxide). A variety of emerging synthetic tools (controlled polymerization and click chemistry) are particularly summarized. An overview on future opportunities and challenges, which are critical to promote biorefinery in the production of renewable chemicals and polymers, is given.
TL;DR: New reactions enabled by a single class of ligands, phosphine-sulfonate (ortho-phosphinobenzenesulfonates), using their palladium complexes, are summarized, which have developed four unusual reactions, and three of these have produced novel types of polymers.
Abstract: Ligands, Lewis bases that coordinate to the metal center in a complex, can completely change the catalytic behavior of the metal center. In this Account, we summarize new reactions enabled by a single class of ligands, phosphine–sulfonates (ortho-phosphinobenzenesulfonates). Using their palladium complexes, we have developed four unusual reactions, and three of these have produced novel types of polymers.In one case, we have produced linear high-molecular weight polyethylene, a type of polymer that group 10 metal catalysts do not typically produce. Secondly, complexes using these ligands catalyzed the formation of linear poly(ethylene-co-polar vinyl monomers). Before the use of phosphine–sulfonate catalysts, researchers could only produce ethylene/polar monomer copolymers that have different branched structures rather than linear ones, depending on whether the polymers were produced by a radical polymerization or a group 10 metal catalyzed coordination polymerization. Thirdly, these phosphine–sulfonate ca...
TL;DR: This combined synthetic, characterization, and computational approach predicts the adsorptive properties of crystalline MTV-MOF systems and is a first step in resolving the more general problem of spatial disorder in other ordered materials, including mesoporous materials, functionalized polymers, and defect distributions within crystalline solids.
Abstract: We determined the heterogeneous mesoscale spatial apportionment of functional groups in a series of multivariate metal-organic frameworks (MTV-MOF-5) containing BDC (1,4-benzenedicarboxylate) linkers with different functional groups--B (BDC-NH2), E (BDC-NO2), F [(BDC-(CH3)2], H [BDC-(OC3H5)2], and I [BDC-(OC7H7)2]--using solid-state nuclear magnetic resonance measurements combined with molecular simulations. Our analysis reveals that these methods discern between random (EF), alternating (EI and EHI), and various cluster (BF) forms of functional group apportionments. This combined synthetic, characterization, and computational approach predicts the adsorptive properties of crystalline MTV-MOF systems. This methodology, developed in the context of ordered frameworks, is a first step in resolving the more general problem of spatial disorder in other ordered materials, including mesoporous materials, functionalized polymers, and defect distributions within crystalline solids.