Macromolecular Rapid Communications最新文献

Zwitterionic polymers are an important class of polymers with far-ranging applications. In the widely studied poly(meth)acrylate and poly(meth) acrylamide-based zwitterions, properties can be tuned by changing the nature of substituents attached to ammonium ions. However, these changes influenced salt tolerance of zwitterionic polymers only to a limited extent. Upon adding salt these polymers expanded in solution initially. Further increase in salt concentration caused the polymer chains to shrink similar to the common water soluble, uncharged polymers thereby deteriorating the viscosity of aqueous solutions. In contrast to the conventional poly(meth)acrylate and poly(meth)acrylamide-based zwitterions, zwitterionic copolymaleimides showed substituent dependent salt-tolerant nature. In the absence of any substituent on the polymer backbone such as zwitterionic poly(ethylene-alt-maleimide) (ZI-PEMA) the viscosity of salt solutions increased both with the increasing salt concentration as well as the concentration of polymer. This is likely due to the continuous expansion of polymer coil in salt solutions with increasing salt concentration caused primarily by the rigidity of the polymer backbone. ZI-PEMA also enhanced the saturation limit of mono- and divalent salts like sodium chloride and hydrated calcium bromide in water. This property is useful for various applications like fish curing, for making high-density fluids, refrigeration, etc. across various industrial sectors.

Tetrafluoroethylene (TFE) terpolymers have emerged as advantageous substitutes for polytetrafluoroethylene (PTFE). Therefore, they are being considered as alternatives to PTFE in many application areas. The advantages of TFE terpolymers include their facile processability at elevated temperatures, their solubility in some polar organic solvents, their inertness against aqueous acids, aqueous bases and a large number of mostly nonpolar organic solvents, their low dielectric constant, their low refractive index as well as useful electro- and thermochemical properties. This review on TFE terpolymers focuses on their processing including shaping and surface modification as well as on selected properties including wettability, dielectric properties, mechanical response behavior, chemical stability, and degradability. Applications including their use as elastomeric sealing material, liner and cladding layer as well as their use as material for membranes, microfluidic devices, photonics, photovoltaics, energy storage, energy harvesting, sensors, and nanothermitic composites will be discussed. The review concludes with a discussion of the future potential of TFE terpolymers and scientific challenges to be addressed by future research on TFE terpolymers.

Polymerization of primary amine-containing monomers is challenging because the amine inhibits polymerization catalyst activity. An alternative approach to access primary amine functionalized polymers is postpolymerization modification. To this end, the hydroaminoalkylation of vinyl-terminated polyolefins with N-(trimethylsilyl)benzylamine is used to prepare primary amine-terminated polyolefins, with the free primary amine substituent being revealed upon hydrolytic work up. These materials are spectroscopically characterized, and an investigation of thermal properties by differential scanning calorimetry and thermogravimetric analysis is completed. These results show that the primary amine substituent increases the glass transition temperature and improves thermal stability. The reactive primary amine functionality is used in the photo-oxidative dimerization of polyolefins to demonstrate how this elusive functionality can be applied in oligomer valorization.

Hydrogels are widely used in biological dressing, tissue scaffolding, drug delivery, sensors, and other promising applications owing to their water-rich soft structures, biocompatibility, and adjustable mechanical properties. However, most of the conventional hydrogels are isotropic. The anisotropic structures existed widely in the organizational structure of plants and animals, which played a crucial role in biological systems. In this work, a method of limited domain swelling to prepare anisotropic hydrogels is proposed. Through spatially controlled swelling, the extension direction of hydrogels can be limited by a tailored mold, further achieving anisotropic hydrogels with concentration gradients. The external solution serves as a swelling solution to promote swelling and extension of the hydrogel matrix in a mold which can control the extension direction. Due to the diversity of external solutions, the method can be applied to prepare a variety of stimulus-responsive polymers. The limited domain swelling method is promising for the construction of anisotropic hydrogels with different structures and properties.

Hydrophobic antifouling polymers capable of self-healing performance are highly desirable for industrial applications. However, the construction of self-healing, hydrophobic antifouling polymers is challenging considering their complex fouling environments, which are humid in aqueous environment. In this work, a self-healing hydrophobic polymer containing Fe³⁺-catechol coordination applicable to antifouling is synthesized. The hydrophobic fluoroalkyl segments in the polymers formed unique domains dispersed in a polydimethylsiloxane matrix. The as-synthesized polymers can completely restore their tensile strength, and their self-healing efficiency is above 90% in both artificial seawater and pure water because of the dynamic Fe³⁺-catechol coordination interactions. The as-synthesized polymer exhibited self-healing and antifouling properties against common marine bacteria. The colony adhesion and self-healing processes of the damaged coating in artificial seawater containing marine bacteria are characterized by laser confocal microscopy. This strategy may be useful for the development of future polymeric antifouling materials.

Phenolic aerogels based on resorcinol-formaldehyde (RF) are among the best thermally insulating materials. However, the hydrophilicity inherent to the free phenolic moiety of RF gels generally limits their actual range of applications. Prior efforts to render phenolic gels hydrophobic are restricted to post-synthetic functionalizations of hydrophilic gels, processes that are often limited in efficiency, scope, and/or longevity. Here, an acid-mediated conversion of 1,3,5-trimethoxybenzene with formaldehyde is reported, yielding monolithic trimethoxybenzene-formaldehyde (TMBF) aerogels and xerogels with low density (0.11-0.30 g cm^-3), high porosity (74-92 %), inner surface areas (S_BET) of up to 284 m² g^-1, and thermal conductivity of 34.5-43.9 mW m^-1 K^-1. For a monolithic xerogel based on TMBF xerogels an unprecedently low thermal conductivity of 34.5 mW m^-1 K^-1 could be achieved. In addition, all TMBF gels are thermally stable (degradation >280-310 °C) and highly hydrophobic (water contact angles 130°-156°). As such, TMBF serves as a new class of inherently hydrophobic aerogels and xerogels and useful complement to RF materials.

To cope with the constraints of conventional drug delivery systems, site-specific drug delivery systems are the major focus of researchers. The present research developed water-swellable, pH-responsive methacrylic acid-based hydrogel scaffolds of Artemisia vulgaris seed mucilage with mucin and loaded with acyclovir sodium as a model drug. The developed hydrogel discs are evaluated for diverse parameters. Drug loading efficiency in all formulations ranges from 63% to 75%. The hydrogels exhibited pH-dependent swelling, displaying optimum swelling in a phosphate buffer (pH 7.4), and insignificant swelling in an acidic buffer (pH 1.2), in addition, they responded well to electrolyte concentrations. The sol-gel fraction is estimated ranging from 60 to 95%. Dissolution studies unveiled sustained drug release for 24 h in a phosphate buffer of pH 7.4, exhibiting zero-order release kinetics. Moreover, FTIR spectra confirmed the drug-excipient compatibility. SEM photomicrographs revealed a rough and porous surface of hydrogel discs with several pores and channels. The PXRD diffractograms exposed the amorphous nature of the polymeric blends. The findings of acute toxicity studies proved the developed hydrogel network is biocompatible. Therefore, these outcomes connote the newly created network as a smart delivery system, able to dispatch acyclovir sodium into the intestinal segment for a prolonged period.

The pursuit of innovative organic materials and the examination of the "structure-function" correlation in lithium-ion batteries (LIBs) are crucial and highly desirable. Current research focuses on the creation of novel conjugated organic polymers with polycarbonyl groups and examining the impact of electrode structure on the function of lithium-ion batteries. In this paper, two novel cyanovinylene-based conjugated organic polymers, NBA-TFB and NBA-TFPB, are synthesized using a Knoevenagel condensation reaction with naphthalene diimide as the integral unit. The performance of NBA-TFB and NBA-TFPB as cathodes in lithium-ion batteries is investigated. Improved conductivity and increased active site density in NBA-TFPB resulted in superior electrochemistry compared to NBA-TFB. Specifically, NBA-TFPB exhibited a larger reversible capacity (87.58 mAh g^-1 at 0.2C and 88.34% retention after 100 cycles), exceptional rate capability (66.13 mAh g^-1 at 5C), and robust cycling stability (99.58% coulombic efficiency at 1C and 60.71% retention after 2000 cycles). This study expands the family of diimide-based naphthalene polymers and provides a strategy for enhancing the performance of organic electrode materials containing polycarbonyl structure.

2D covalent organic frameworks (COFs) are attractive for fluorescence sensing due to their lightweight, robust, and highly ordered porous structures. However, the highly conjugated structures between adjacent layers of covalent organic frameworks can often result in aggregation-caused quenching (ACQ) properties. Here, the study designs two flexible hydrazone-linked COFs to suppress ACQ effects, thereby enhancing their luminescent activities. Furthermore, the high density of nitrogen and oxygen atoms on these flexible walls serves as binding sites for hydrogen bonding interactions, indicating sensitivity and selectivity towards 2,4,6-trinitrophenol detection.

Stretchable organic solar cells (SOSCs) have advanced rapidly in the last few years as power sources required to realize portable and wearable electronics become available. Through rational material and device engineering, SOSCs are now able to retain their photovoltaic performance even when subjected to repeated mechanical deformations. However, reconciling a high efficiency and an excellent stretchability is still a huge challenge, and the development of SOSCs has lagged far behind that of flexible OSCs. In this perspective article, recent strategies for imparting mechanical robustness to SOSCs while maintaining high power conversion efficiency are reviewed, with emphasis on the molecular design of active layers. Initially, an overview of molecular design approaches and recent research advances is provided in improving the stretchability of active layers, including donors, acceptors, and single-component materials. Subsequently, another common strategy for regulating photovoltaic and mechanical properties of SOSCs, namely multi-component system, is summarized and analyzed. Lastly, considering that SOSCs research is in its infancy, the current challenges and future directions are pointed out.