Bioinspired Sustainable Polymer with Stereochemistry-Controllable Thermomechanical Properties

Stereocontrolled Phenol-Yne Click Polymerization Toward High-Performance Bioplastics with Closed-Loop Recyclability

Hydroxyl-yne click polymerization is a highly atom-economic and powerful tool for constructing sequence-controlled and structure-diverse unsaturated polymers. However, the cis/trans stereochemistry remains underdeveloped, thus lacking a stereodivergent synthesis of stereocontrolled polymers. Herein, we first report the organocatalyzed stereocontrolled phenol-yne click polymerization of bioderived diphenols and dipropiolates by judiciously changing the substrates, catalysts, and reaction solvents. Various sequence- and stereocontrolled poly(vinyl ether ester)s were effectively synthesized under mild reaction conditions, in which the trans content in the polymeric backbone can be proportionally altered in the range of 46%-100%. More importantly, the bulk properties of these materials such as thermal (Td,5% of 329-362 °C; Tg of 48-92 °C), mechanical (ultimate tensile strengths of 41-89 MPa, tensile moduli of 960-1991 MPa, and elongations at break of 71%-242%), and transport properties (oxygen transmission rates of 0.2-0.3 bar and water vapor transmission rates of 1.3-2.8 g mm m-2 day-1) can be tuned broadly. Moreover, the installed dynamic acetal moieties contribute to the excellent degradability and recyclability of these materials. This study provides an efficient and sustainable strategy for synthesizing stereoregulated biopolymers with closed-loop recyclability, thereby expanding the chemical diversity of click polymers with structure-controlled and tailored properties.

Impact of molecular configuration on the photoluminescence and electrical characteristics of poly-pyrrol-thiazol-imine polymers films

The optical, photoluminescence, and electrical properties of Poly(Z)-PTI and Poly(E)-PTI, two Poly-Pyrrol-Thiazol-Imine polymers with comparable chemical structures but distinct configurations, were examined. Using the dip-casting method, polymer films were deposited on ITO substrates. UV-VIS spectroscopy revealed that both polymers diverged between 500 and 800 nm, showing the impact of molecular arrangement, but showed similar absorption behavior for wavelengths shorter than 500 nm. For Poly(Z)-PTI, the direct optical energy gaps were 2.06 eV, while for Poly(E)-PTI, they were 1.78 eV. Poly(Z)-PTI displayed an emission peak at 610 nm (red) according to laser photoluminescence spectra, while Poly(E)-PTI peaked at 563 nm (green-yellow). The capacitance behavior was revealed by electrochemical impedance spectroscopy. Nyquist plots suggested an equivalent circuit model of Rs (CRct)(QR)(CR) for both polymers, and the relaxation times were 15.9 ns for Poly(Z)-PTI and 89.5 ns for Poly(E)-PTI. The Mott-Schottky analysis verified the n-type conductivity, revealing 2.18 × 1016 cm- 3 carrier densities for Poly(Z)-PTI and 1.78 × 1016 cm- 3 for Poly(E)-PTI. At lower frequencies, both polymers exhibited limited conductivity and large dielectric constants. Insights into the possible uses of Poly-Pyrrol-Thiazol-Imine polymers in electrical and optoelectronic devices are provided by this study, which emphasizes the influence of molecular configuration on these polymers' characteristics.

Characterization of Biodegradable Polymers for Porous Structure: Further Steps toward Sustainable Plastics

Plastic pollution poses a significant environmental challenge, necessitating the investigation of bioplastics with reduced end-of-life impact. This study systematically characterizes four promising bioplastics-polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and polylactic acid (PLA). Through a comprehensive analysis of their chemical, thermal, and mechanical properties, we elucidate their structural intricacies, processing behaviors, and potential morphologies. Employing an environmentally friendly process utilizing supercritical carbon dioxide, we successfully produced porous materials with microcellular structures. PBAT, PBS, and PLA exhibit closed-cell morphologies, while PHBV presents open cells, reflecting their distinct overall properties. Notably, PBAT foam demonstrated an average porous area of 1030.86 μm2, PBS showed an average porous area of 673 μm2, PHBV displayed open pores with an average area of 116.6 μm2, and PLA exhibited an average porous area of 620 μm2. Despite the intricacies involved in correlating morphology with material properties, the observed variations in pore area sizes align with the findings from chemical, thermal, and mechanical characterization. This alignment enhances our understanding of the morphological characteristics of each sample. Therefore, here, we report an advancement and comprehensive research in bioplastics, offering deeper insights into their properties and potential morphologies with an easy sustainable foaming process. The alignment of the process with sustainability principles, coupled with the unique features of each polymer, positions them as environmentally conscious and versatile materials for a range of applications.

Synthetic Polyisoprene Rubber as a Mimic of Natural Rubber: Recent Advances on Synthesis, Nanocomposites, and Applications

Up to now, rubber materials have been used in a wide range of applications, from automotive parts to special-design engineering pieces, as well as in the pharmaceutical, food, electronics, and military industries, among others. Since the discovery of the vulcanization of natural rubber (NR) in 1838, the continuous demand for this material has intensified the quest for a synthetic substitute with similar properties. In this regard, synthetic polyisoprene rubber (IR) emerged as an attractive alternative. However, despite the efforts made, some properties of natural rubber have been difficult to match (i.e., superior mechanical properties) due not only to its high content of cis-1,4-polyisoprene but also because its structure is considered a naturally occurring nanocomposite. In this sense, cutting-edge research has proposed the synthesis of nanocomposites with synthetic rubber, obtaining the same properties as natural rubber. This review focuses on the synthesis, structure, and properties of natural and synthetic rubber, with a special interest in the synthesis of IR nanocomposites, giving the reader a comprehensive reference on how to achieve a mimic of NR.