Macromolecular Chemistry and Physics最新文献

Benzocyclobutene (BCB) stands out as a compound of remarkable structural distinction, featuring a thermodynamically stable benzene ring coupled with a kinetically dynamic four-membered ring. This unique structure allows for ring-opening reactions under specific conditions, leading to the formation of crosslinking products. The primary initiation for the ring-opening of the four-membered ring in BCB is heat, although mechanical stress and light exposure can also trigger this transformation. This ability has catapulted it to prominence in the field of polymer material development. It has spurred the creation of a vast array of polymers that incorporate BCB groups either in their main chains or side chains, showcasing BCB's extensive applicability as a crosslinking agent. Additionally, BCB-based polymers (BCB polymer) exhibit a suite of desirable properties, such as exceptional dielectric characteristics, chemical and thermal resilience, minimal thermal expansion, and low moisture uptake. These attributes render them particularly suitable for a range of applications, including electronic packaging, silicon-based photonic integration, flat panel display technology, biomedical devices, and beyond. This paper delves into the various methods of inducing ring-opening crosslinking in BCB, summarizes the recent advancements in performance enhancement of BCB polymer materials, and examines their wide applications in different fields.

One possible way to store the excess CO₂ present in atmosphere is to use it as a reagent for the synthesis of commodities. In particular, CO₂ and epoxides can be copolymerized to produce a large variety of polycarbonates which appear very promising in various application fields. Further, the addition of an appropriate transfer agent in the reaction mixture promotes the formation of telechelic polycarbonates which can be used where specific functional polymers are necessary. In this work, (hydroxyethyl) methacrylate and 2-hydroxyethyl-2-bromoisobutyrate species are exploited as transfer agents in the copolymerization of CO₂ and cyclohexene oxide, in the presence of a macrocyclic phenolate dimagnesium catalyst. The effect of the transfer agent concentration on the polycarbonate characteristics is evaluated. Finally, the obtained telechelic polycarbonates are used as macromonomers and macroinitiators in the synthesis of statistical and block copolymers.

The relentless increase in global energy consumption, coupled with the detrimental effects of over-reliance on non-renewable fossil fuels, has necessitated a paradigm shift in the energy industry towards sustainable energy sources. Thermoelectric materials have emerged as a promising avenue for harnessing waste heat, offering a viable solution to the dual challenges of energy scarcity and environmental pollution. Compared with traditional electronic thermoelectric materials, ionic thermoelectric (i-TE) materials have received increasing attention. This review provides an overview of the recent advancements in i-TE materials based on the thermodiffusion effect, including an in-depth analysis of the fundamental principle, material design, and potential applications. The significance of material selection is highlighted, with types of i-TE materials ranging from liquid to quasi-solid and solid states, each presenting unique advantages and challenges. The innovative microstructural engineering and regulating interactions are identified as key strategies to enhance the thermoelectric performance of i-TE materials. Furthermore, the applications in capacitors and generators and sensing devices are summarized, demonstrating their potentials in varieties of scenarios. Encouraged by the recent rapid progresses, it is believed that the ionic i-TE materials and related technology are expected to generate practical impacts in the future solutions for sustainable energy.

Technologies that facilitate recycling are attracting considerable interest from the perspective of resource constraints. In the present study, degradable primer films are to facilitate the removal of strongly bonded joints. This film consists of a light-cured trifunctional anthracene compound that thermally decomposes to its original liquid state. To demonstrate its function as a degradable primer film and verify its range of applications, various substrates, such as aluminum alloys, stainless steel, carbon fiber-reinforced plastics, carbon fiber-reinforced thermoplastics, and polyetheretherketone, are bonded through the primer film using a two-component epoxy adhesive. All the single-lap specimens exhibit strengths above 10 MPa, which is sufficient, or base material fracture. When adhesive bonding specimens prepared using the same procedure are heated at 180 °C to transform the coating film to a liquid state, the bond strength is significantly reduced. The primer film is expected to exhibit long-term stability of more than one year at ≈60 °C.

With the development of new energy vehicles, there is a growing demand for automotive interior materials that meet higher standards. In this case, thermoplastic elastomer (TPE), being a completely recyclable environment-friendly polymer material, possesses advantages such as plasticizers and solvents free, excellent mechanical properties, less volatile organic compounds (VOC) release and low processing cost compared with polyvinyl chloride (PVC), polyurethane (PU), and thermoplastic polyolefin (TPO) skins, become a desirable choice for automotive injection molding automotive skin. Hence, this work investigates the influence of hydrogenated styrene-butadiene-styrene block copolymer (SEBS) molecular weight, chemical structure, and polypropylene (PP) doping amount on thermodynamic, crystallinity, rheological, and mechanical properties of TPE, which provides a scientific basis for guiding the material selection of TPE injection molding skin.

Vat photopolymerization (VPP) of highly aromatic polyurethanes (PUs) expands the library of additive manufacturing (AM) materials and enables a vast array of ductile thermoplastics, rigid and flexible thermosets, and elastomers. Aromatic diisocyanates and various diols enable printing of rigid, highly aromatic cross-linked parts, which offer high glass transition temperatures and tunable thermomechanical performance. The judicious control of molecular weight of the photo-reactive telechelic oligomers allows for a fundamental study of the influence of cross-link density in highly aromatic 3D PU printed objects. VPP AM produces objects with high resolution, smooth surface finish, and isotropic mechanical properties. Thermal post-processing is critical in maintaining excellent thermomechanical properties with semi-crystallinity as a function of cross-link density. Due to the presence of two ester carbonyls in the bis(2-hydroxyethyl) terephthalate chain extender, the printed parts are readily amenable to depolymerization with methanolysis to produce difunctional dimethyl dicarbamates under modest reaction conditions. Dimethyl dicarbamates serve as suitable monomers for subsequent polycondensation.

The growing demand for energy-storage devices has raised inevitable concerns regarding the availability of redox-active inorganic compounds and metals. It is expected that some of the inorganic compounds will be replaced by organic redox polymers, which are produced from abundant sources using environmentally benign processes, and they exhibit inherent advantages, including flexibility, processability, and biocompatibility. Redox polymers contain groups that can be reversibly reduced and oxidized by gaining and releasing electrons, respectively, and constitute an emerging class of functional organic materials. This article begins with a retrospective discussion of polymers and their electron exchange concepts, presenting them as old but new materials. The basics of electrochemical redox couples are briefly reintroduced, and the chemical design strategies for extending them to redox polymers are summarized. Subsequently, the efficient and reversible charge propagation and storage in densely populated redox-active sites on soft polymer platforms are discussed. The potential to employ redox polymers in rechargeable charge-storage applications and next-generation devices is discussed, along with the current challenges and prospects. This outlook suggests fundamental questions and proposes interesting topics for redox polymers to facilitate their development as valuable materials for use in sustainable technologies.

The new halogen-free donor polymer PCN6 is constructed using 2-ethylhexyl-4,6-dibromo-3-cyano-thieno[3,4-b]thiophene as acceptor (A) block, and is compared in detail with the commercially available PTB7-Th. It is found that PCN6 has a wider film absorption (300–700 nm) and lower highest occupied molecular orbital (HOMO) energy levels (−5.52 eV) than PTB7-Th (−5.34 eV), suggesting a great advantage of the monocyano-functionalized modification strategy in terms of molecular absorption and energy level tuning. The performance difference between PCN6:Y6- and PTB7-Th:Y6-based organic solar cells (OSCs) is compared by a series of studies including light intensity dependence, carrier mobility, AFM, TEM, and GIWAXS. The results show that PCN6:Y6-based OSCs have stronger crystallinity, better charge transport, higher and more balanced carrier mobility, and less exciton complex loss. Therefore, the power conversion efficiency (PCE) of PCN6:Y6-based OSCs reaches 11.34%, while the PCE of PTB7-Th:Y6-based OSCs is only 9.02%. These results suggest that 2-ethylhexyl-4,6-dibromo-3-cyano-thieno[3,4-b]thiophene is an excellent A block for the construction of halogen-free donor polymers with low HOMO energy levels, and also demonstrate that the introduction of cyano in the conjugated backbone of polymers is a good strategy to achieve high-performance OSCs.