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Abstract Most triblock copolymer-based physical hydrogels form three-dimensional networks through micellar packing, and formation of polymer loops represents a topological defect that diminishes hydrogel elasticity. This effect can be mitigated by maximizing the fraction of elastically effective bridges in the hydrogel network. Herein, we report hydrogels constructed by complexing oppositely charged multiblock copolymers designed with a sequence pattern that maximizes the entropic and enthalpic penalty of micellization. These copolymers self-assemble into branched and bridge-rich network units (netmers), instead of forming sparsely interlinked micelles. We find that the storage modulus of the netmer-based hydrogel is 11.5 times higher than that of the micelle-based hydrogel. Complementary coarse grained molecular dynamics simulations reveal that in the netmer-based hydrogels, the numbers of charge-complexed nodes and mechanically reinforcing bridges increase substantially relative to micelle-based hydrogels.

Abstract Mussel periostracum, a nonliving multifunctional gel that covers the rigid inorganic shells of mussels, provides protection against mechanical impacts, biofouling, and corrosion in harsh ocean environments. The inner part of the periostracum, which emerges from biological tissues, functions as a natural interface between tissue and inorganic materials. The periostracum shows significant potential for application in implantable devices that provide interfaces; however, this system remains unexplored. In this study, we revealed that the inner periostracum performs graded mechanical functions and efficiently dissipates energy to accommodate differences in stiffness and stress types on both sides. On the tissue end, the lightly pigmented periostracum exhibits extensibility and energy dissipation under repetitive tension. This process was facilitated by the slipping and reassembly of β-strands in the discovered major proteins, which we named periostracin proteins. On the shell end, the highly pigmented, mineralized, and porous segment of the periostracum provided stiffness and cushioned against compressive stresses exerted by the shell valves during closure. These findings offer a novel possibilities for the design of interfaces that bridge human tissue and devices.

Abstract Self‐healing polymeric materials, which can repair physical damage, offer promising prospects for protective applications across various industries. Although prolonged durability and resource conservation are key advantages, focusing solely on mechanical recovery may limit the market potential of these materials. The unique physical properties of self‐healing polymers, such as interfacial reduction, seamless connection lines, temperature/pressure responses, and phase transitions, enable a multitude of innovative applications. In this perspective, the diverse applications of self‐healing polymers beyond their traditional mechanical strength are emphasized and their potential in various sectors such as food packaging, damage‐reporting, radiation shielding, acoustic conservation, biomedical monitoring, and tissue regeneration is explored. With regards to the commercialization challenges, including scalability, robustness, and performance degradation under extreme conditions, strategies to overcome these limitations and promote successful industrialization are discussed. Furthermore, the potential impacts of self‐healing materials on future research directions, encompassing environmental sustainability, advanced computational techniques, integration with emerging technologies, and tailoring materials for specific applications are examined. This perspective aims to inspire interdisciplinary approaches and foster the adoption of self‐healing materials in various real‐life settings, ultimately contributing to the development of next‐generation materials.

The demand for face masks is increasing exponentially due to the coronavirus pandemic and the particulate matter (PM) in the atmosphere. As a result, an enormous number of disposable mask filters have been produced and discarded, contributing to plastic waste. Underprivileged people who cannot afford to purchase commercial face masks have started making fabric masks with waste clothing; however, this material does not effectively filter viruses or PM. Therefore, in this study, a chitosan coating was applied to clothing fabrics to increase their effectiveness as face masks. The improvement in the PM removal efficiency owing to the chitosan polymer was observed for stocking, innerwear, and bamboo materials, but not for cotton. Furthermore, chitosan prepared in the form of a nanowhisker (CsW) achieved a PM 2.5 removal efficiency of 96% in a five-layer cotton fabric. In addition, a commercial biodegradable poly(lactic acid) filter was coated with CsW, which increased the PM 2.5 removal efficiency from 67% to 83%. Additionally, microbial growth was significantly suppressed in the chitosan-coated fabrics, and the degree to which it was suppressed depended on the coating concentration. The study will aid in the utilization of face mask filters that are more sustainable, efficient, and widely accessible.

Abstract Among plastic items, single‐use straws are particularly detrimental to marine ecosystems because such straws, including those made of poly(lactic acid) (PLA), are sharp and extremely slowly degradable in the ocean. While paper straws are promising alternatives, they exhibit hydration‐induced swelling even when coated with a non‐degradable plastic coating and promote effervescence (fizzing) in soft drinks owing to their surface heterogeneities. In this study, upgraded paper straw is coated with poly(butylene succinate) cellulose nanocrystal (PBS/CNC) composites. CNC increases adhesion to paper owing to their similar chemical structures, optimizes crystalline PBS spherulites through effective nucleation, and reinforces the matrix through its anisotropic and rigid features. The straws are not only anti‐fizzing when used with soft drinks owing to their homogeneous and seamless surface coatings, but also highly water‐resistant and tough owing to their watertight surfaces. All degradable components effectively decompose under aerobic composting and in the marine environment. This technology contributes to United Nations Sustainable Development Goal 14 (Life Below Water).

Super engineering plastics that utilise bio-derived cyclic monomers rarely offer the same thermal/mechanical properties, scalability and recyclability as petrochemical derived plastics. Here the authors use a phase transfer catalyst to synthesise a transparent, recyclable and tough isosorbide-based polymer with a high molecular weight.

Abstract The demand for face masks is increasing exponentially due to the coronavirus pandemic and issues associated with airborne particulate matter (PM). However, both conventional electrostatic‐ and nanosieve‐based mask filters are single‐use and are not degradable or recyclable, which creates serious waste problems. In addition, the former loses function under humid conditions, while the latter operates with a significant air‐pressure drop and suffers from relatively fast pore blockage. Herein, a biodegradable, moisture‐resistant, highly breathable, and high‐performance fibrous mask filter is developed. Briefly, two biodegradable microfiber and nanofiber mats are integrated into a Janus membrane filter and then coated by cationically charged chitosan nanowhiskers. This filter is as efficient as the commercial N95 filter and removes 98.3% of 2.5 µm PM. The nanofiber physically sieves fine PM and the microfiber provides a low pressure differential of 59 Pa, which is comfortable for human breathing. In contrast to the dramatic performance decline of the commercial N95 filter when exposed to moisture, this filter exhibits negligible performance loss and is therefore multi‐usable because the permanent dipoles of the chitosan adsorb ultrafine PM (e.g., nitrogen and sulfur oxides). Importantly, this filter completely decomposes within 4 weeks in composting soil.

Although collagens from vertebrates are mainly used in regenerative medicine, the most elusive issue in the collagen-based biomedical scaffolds is its insufficient mechanical strength. To solve this problem, electrospun collagen composites with chitins were prepared and molecular interactions which are the cause of the mechanical improvement in the composites were investigated by two-dimensional correlation spectroscopy (2DCOS). The electrospun collagen is composed of two kinds of polymorphs, α- and β-chitin, showing different mechanical enhancement and molecular interactions due to different inherent configurations in the crystal structure, resulting in solvent and polymer susceptibility. The collagen/α-chitin has two distinctive phases in the composite, but β-chitin composite has a relatively homogeneous phase. The β-chitin composite showed better tensile strength with ~41% and ~14% higher strength compared to collagen and α-chitin composites, respectively, due to a favorable secondary interaction, i.e., inter- rather than intra-molecular hydrogen bonds. The revealed molecular interaction indicates that β-chitin prefers to form inter-molecular hydrogen bonds with collagen by rearranging their uncrumpled crystalline regions, unlike α-chitin.

Sustainability has become increasingly important as environmental issues continue to rise. Biodegradable polymers offer a sustainable solution as they use biomass. In this study, biochar (BC) prepared by the pyrolysis of biomass was compounded with polybutylene succinate (PBS) to enhance its Young's modulus, and the residual BC was shown to amend the soil, following degradation. The incorporation of biochar into the PBS matrix is strategically achieved through a BC with treatment involving an aprotic polar solvent. This process not only reduces the size of the biochar particles but also ensures their uniform dispersion within the PBS matrix. As a result, a remarkable 2.5-fold increase in Young's modulus is observed, reaching an impressive 571.04 MPa, compared with the baseline Young's modulus of neat PBS, which stands at 220.92 MPa. Interestingly, the degradation rate of the resulting composites was comparable to that of neat PBS despite the decrease in the number of potential hydrolysis sites owing to the increased Young's modulus of the PBS/BC composite. These sustainable composite exhibited properties different from those of conventional PBS and is expected to be used in potentially novel applications toward environmental sustainability, such as in agricultural mulch films or electronic printing. [ABSTRACT FROM AUTHOR]

Two new species of Gelechiidae, Stenolechia byuni Park, sp. nov. and Acanthophila hallasana Park, sp. nov. are described from Korea. Images of adults and genitalia are given.

Three genera Megacraspedus Zeller, 1839, Aulidiotis Meyrick, 1925, and Cuprina Sinev, 1988 and four species of the superfamily Gelechioidea are reported for the first time from the Korean Peninsula. They are Megacraspedus coleophorodes (Li and Zheng, 1995) and Aulidiotis phoxopterella (Snellen, 1903) of Gelechiidae; Martyringa ussuriella Lvovsky, 1979 of Oecophoridae; and Cuprina fuscella Sinev, 1988 of Stathmopodidae. Images of adults and genitalia of the species are given. Keywords: Lepidoptera, Aulidiotis, Cuprina, Megacraspedus, New record