This review highlights the recent progress made in the area of thermoelectric (TE) applications of conducting polymers and related composites. Several examples of such materials and their TE ...properties are discussed. TE properties of new poly(2,7-carbazole) derivatives are highlighted. References are also made to carbon nanotube/polymer composites and their improved electrical and TE performance. Studies on polymer/inorganic materials composites have also taken a step forward and have shown very promising TE properties.
Dwindling fossil resources, surging energy demand and global warming stimulate growing demand for renewable polymer products with low carbon footprint. Going well beyond the limited scope of natural ...polymers, biomass conversion in biorefineries and chemical carbon dioxide fixation are teamed up with highly effective tailoring, processing and recycling of polymers. “Green monomers” from biorefineries, and “renewable oil”, gained from plastics' and bio wastes, render synthetic polymers renewable without impairing their property profiles and recycling. In context of biofuel production, limitations of the green economy concepts are clearly visible. Dreams and reality of “green polymers” are highlighted. Regardless of their new greenish touch, highly versatile and cost‐effective polymers play an essential role in sustainable development.
Dwindling fossil resources, surging energy demand, and global warming account for paradigm change and growing demand for renewable polymer products with low carbon footprint. “Green monomers” from biorefineries, carbon dioxide conversion, and “renewable oil”, gained from plastics' and bio wastes, render synthetic polymers renewable without impairing their property profiles and recycling. Dreams and reality of “green polymers” are highlighted.
Over the last ten years, the development of synthetic polymers containing controlled monomer sequences has become a prominent topic in fundamental and applied polymer science. This emerging area is ...particularly broad and combines classical polymer chemistry tools with techniques imported from other domains such as biology, biochemistry, organic synthesis, engineering, and bioanalytics. Consequently, it also generates new structures, terminologies, and applications that are not within the traditional scope of polymer science. The term “sequence‐controlled polymers” (SCPs) was recently proposed as a generic name to describe all these recent trends. However, since the field of SCPs has been growing very rapidly in recent literature, it is urgent to accurately define its scientific frontiers. In this important context, this review is an attempt to define, rationalize, and classify the field of SCPs. In particular, all synthetic approaches that have been reported for the synthesis of SCPs are discussed and categorized. In addition, the characterization tools, properties, and potential applications of these new polymers are described herein. Overall, this review serves as a reference guide for understanding the burgeoning field of SCPs.
The field of sequence‐controlled polymers is an exciting emerging area that combines classical polymer science aspects with concepts imported from other disciplines. In this context, the aim of this review is to help the readers understand this young, yet fast‐moving area of research. Thus, the state‐of‐the‐art is described. Additionally, some definitions and categories are also proposed for rationalizing the field.
The past decade has witnessed tremendous advances in the synthesis of polymers that contain elements from the main groups beyond those found in typical organic polymers. Unique properties that arise ...from dramatic differences in bonding and molecular geometry, electronic structure, and chemical reactivity, are exploited in diverse application fields. Herein we highlight recent advances in inorganic backbone polymers, discuss how Lewis acid/base functionalization of polymers results in unprecedented reactivity, and survey conjugated hybrids with unique electronic structures for sensor and device applications.
Polymers go main group! This Review shows how the incorporation of the full range of available main‐group elements into polymers leads to new functional hybrid materials with potential use in diverse application fields ranging from advanced elastomers, responsive gels, biodegradable materials, to organic electronics, imaging agents, sensors, and supported catalysts.
The introduction of graphene-based nanomaterials has prompted the development of flexible nanocomposites for emerging applications in need of superior mechanical, thermal, electrical, optical, and ...chemical performance. These nanocomposites exhibit outstanding structural performance and multifunctional properties by synergistically combining the characteristics of both components if proper structural and interfacial organization is achieved. Here, we briefly introduce the material designs and basic interfacial interactions in the graphene-polymer nanocomposites and the corresponding theoretical models for predicting the mechanical performances of such nanocomposites. Then, we discuss various assembly techniques available for effectively incorporating the strong and flexible graphene-based components into polymer matrices by utilization of weak and strong interfacial interactions available in functionalized graphene sheets. We discuss mechanical performance and briefly summarize other physical (thermal, electrical, barrier, and optical) properties, which are controlled by processing conditions and interfacial interactions. Finally, we present a brief outlook of the developments in graphene-based polymer nanocomposites by discussing the major progress, opportunities, and challenges.
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•Polysaccharide-based SAPs sustainable alternative for conventional, synthetic SAPs.•Semi-synthetic SAPs with fine-tuned properties for specialized applications.•Smart SAPs ...particularly interesting for specific applications such as drug delivery.
The current review provides an overview of different types of superabsorbent polymers (SAPs) together with appropriate strategies elaborated to enable their synthesis. The main focus will be on polysaccharide-based, semi-synthetic and ‘smart’ SAPs along with their derivatives. SAPs have already shown their use in a plethora of applications including diapers, the biomedical field, agriculture, etc. The different polymer classification possibilities are discussed, as well as the classification of the constituting building blocks. The main part of SAPs still has a synthetic origin. However, as they are often not biocompatible, biodegradable or renewable, natural SAPs based on polysaccharides have gained increasing interest. Due to the low solubility of synthetic polymers, purification problems or the need for organic solvents, a trend has emerged towards combining polysaccharides with synthetic monomers to create semi-synthetic, hybrid SAPs for specialized applications with fine-tuned properties including wound dressings, fertilizers or self-healing concrete. These specialized, semi-synthetic SAPs offer strong potential for a series of applications in the future. However, future research in this respect is still needed to optimize homogeneity and to increase gel fractions. A final part of this review includes ‘smart’ SAPs such as SAPs with a T-, electro- and pH-sensitivity. These ‘smart’ SAPs are especially becoming useful for certain biomedical applications such as drug release for which an in vivo location can be targeted. The use of ‘smart’, semi-synthetic SAPs with fine-tuned characteristics combining the best characteristics of both synthetic and natural SAPs, offer the greatest potential for the future.
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•Extrinsic dielectric properties include dipolar and space charge polarizations.•Intrinsic dielectric properties are electronic/atomic/orientational polarizations.•Contributions of ...electronic and atomic polarizations are limited for high κ.•Dipolar glass polymers are good candidates for high energy and low loss dielectrics.•Multilayer films utilize both interfacial and orientational polarizations.
High energy density, high temperature, and low loss polymer dielectrics are highly desirable for electric energy storage applications such as film capacitors in the power electronics of electric vehicles or high-speed trains. Fundamentally, high polarization and low dielectric loss are two conflicting physical properties, because more polarization processes will involve more loss mechanisms. As such, we can only achieve a delicate balance between high dielectric constant and reasonably low loss. This review focuses on achieving low dielectric loss while trying to enhance dielectric constants for dielectric polymers, which can be divided into two categories: extrinsic and intrinsic. For extrinsic dielectric systems, the working mechanisms include dipolar (e.g. nanodielectrics) and space charge (e.g. ion gels) interfacial polarizations. These polarizations do not increase the intrinsic dielectric constants, but cause decreased breakdown strength and increased dielectric loss for polymers. For intrinsic dielectric polymers, the dielectric constant originates from electronic, atomic (or vibrational), and orientational polarizations, which are intrinsic to the polymers themselves. Because of the nature of molecular bonding in organic polymers, the dielectric constant from electronic and atomic polarizations is limited to 2–5 for hydrocarbon-based insulators (i.e., band gap > 4 eV). It is possible to use orientational polarization to enhance intrinsic dielectric constant while keeping reasonably low loss. However, nonlinear ferroelectric switching in ferroelectric polymers must be avoided. Meanwhile, paraelectric polymers often exhibit high electronic conduction due to large chain motion in the paraelectric phase. In this sense, dipolar glassy polymers are more attractive for low loss dielectrics, because frozen chain dynamics enables deep traps to prevent electronic conduction. Both side-chain and main-chain dipolar glass polymers are promising candidates. Furthermore, it is possible to combine intrinsic and extrinsic dielectric properties synergistically in multilayer films to enhance breakdown strength and further reduce dielectric loss for high dielectric constant polar polymers. At last, future research directions are briefly discussed for the ultimate realization of next generation polymer film capacitors.
Fibre-reinforced polymer structures are often used when stiff lightweight materials are required, such as in aircraft, vehicles and biomedical implants. Despite their very high stiffness and strength
..., such lightweight materials require energy- and labour-intensive fabrication processes
, exhibit typically brittle fracture and are difficult to shape and recycle
. This is in stark contrast to lightweight biological materials such as bone, silk and wood, which form by directed self-assembly into complex, hierarchically structured shapes with outstanding mechanical properties
, and are circularly integrated into the environment. Here we demonstrate a three-dimensional (3D) printing approach to generate recyclable lightweight structures with hierarchical architectures, complex geometries and unprecedented stiffness and toughness. Their features arise from the self-assembly of liquid-crystal polymer molecules into highly oriented domains during extrusion of the molten feedstock material. By orienting the molecular domains with the print path, we are able to reinforce the polymer structure according to the expected mechanical stresses, leading to stiffness, strength and toughness that outperform state-of-the-art 3D-printed polymers by an order of magnitude and are comparable with the highest-performance lightweight composites
. The ability to combine the top-down shaping freedom of 3D printing with bottom-up molecular control over polymer orientation opens up the possibility to freely design and realize structures without the typical restrictions of current manufacturing processes.
Traditional shape memory polymers (SMPs) are those capable of memorizing a temporary shape and recovering to the permanent shape upon heating. Although such a basic concept has been known for half a ...century, recent progresses have challenged the conventional understanding of the polymer shape memory effect and significantly expanded the practical potential of SMPs. In this article, notable recent advances in the field of SMPs are highlighted. Particular emphasis is placed on how the new developments have changed the conventional view of SMPs, what they mean for practical applications, and where the future opportunities are.
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Conducting polymers have been widely used in biomedical applications such as biosensors and tissue engineering but their non-degradability still poses a limitation. Therefore, great attention has ...been directed toward the recently developed degradable and electrically conductive polymers (DECPs). The different strategies for synthesis of degradable and conducting polymers containing conducting oligomers are summarized and discussed here as well as the influence of different macromolecular architectures such as linear, star-shaped, hyperbranched and cross-linked DECPs. Blends and composites of biodegradable and conductive polymers are also discussed. The developing trends and challenges with the design of DECPs are also presented.
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