Poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) are well-known biodegadable polyesters due to their outstanding performance. The biodegradation behavior of PLA/PBAT blends in freshwater with sediment is investigated in this study by analyzing the appearance, chemical structure and aggregation structure of their degraded residues via SEM, TG, DSC, gel permeation chromatography (GPC) and XPS. The effect of aggregation structure, hydrophilia and biodegradation mechanisms of PBAT and PLA on the biodegradability of PLA/PBAT blends is illuminated in this work. After biodegradation, the butylene terephthalate unit in the molecular structure of the components and the molecular weight of PLA/PBAT blends decreased, while the content of C-O bond in the composites increased, indicating that the samples indeed degraded. After 24 months of degradation, the increase in the relative peak area proportion of C-O to C=O in PLA/PBAT-25, PLA/PBAT-50 and PLA/PBAT-75 was 62%, 46% and 68%, respectively. The biodegradation rates of PBAT and PLA in the PLA/PBAT blend were lower than those for the respective single polymers.

As a replacement for highly flammable and volatile organic liquid electrolyte, solid polymer electrolyte shows attractive practical prospect in high-energy lithium metal batteries. However, unsatisfied interface performance and ionic conductivities are two critical challenges. A common strategy involves introducing organic solvents or plasticizers, but this violates the original intention of security design. Here, an electrolyte concept called liquid polymer electrolyte without any small molecular solvents is proposed for safe and high-performance batteries, based on the design of a room-temperature liquid-state brush-like polymer as the sole solvent of lithium salts. This liquid polymer electrolyte is non-flammable and exhibits high ionic conductivity (1.09 $$\times$$× 10⁻⁴S cm⁻¹ at 25 °C), significant lithium dendrite suppression, and stable long-term cycling over a wide operating temperature range ( ≥ 1000 cycles at 60 °C and 90 °C). Moreover, the pouch cell can resist thermal abuse, vacuum environment, and mechanical abuse. This electrolyte and design strategy are expected to provide enlightening ideas for the development of safe and high-performance polymer electrolytes.

We study a one-hop device-to-device (D2D)-assisted wireless caching network, where popular files are randomly and independently cached in the memory of end users. Each user may obtain the requested files from its own memory without any transmission, or from a helper through a one-hop D2D transmission, or from the base station. We formulate a joint D2D link scheduling and power allocation problem to maximize the system throughput. However, the problem is non-convex, and obtaining an optimal solution is computationally hard. Alternatively, we decompose the problem into a D2D link-scheduling problem and an optimal power allocation problem. To solve the two subproblems, we first develop a D2D link-scheduling algorithm to select the largest number of D2D links satisfying both the signal to interference plus noise ratio and the transmit power constraints. Then, we develop an optimal power allocation algorithm to maximize the minimum transmission rate of the scheduled D2D links. Numerical results indicate that both the number of the scheduled D2D links and the system throughput can be improved simultaneously with the Zipf-distribution caching scheme, the proposed D2D link-scheduling algorithm, and the proposed optimal power allocation algorithm compared with the state of the arts.

Aramid fiber products have been widely used in both civil and military fields. However, the improper disposal of waste aramid fiber products could result in potential environmental problems and waste of valuable resources. In comparison with mechanical recycling, recycling of aramid fibers into aramid nanofibers (ANFs) as a novel 1D building block for functional materials has better development prospects and has got greater attention. However, the time-consuming preparation cycle of the existing approaches is not conducive to rapid and large-scale production or an in situ study of the mechanism. Herein, based on the in situ size control of solid KOH, a proton donor-assisted deprotonation system for both Kevlar fibers and their various products, i.e. KOH(aq)/DMSO system, was developed to prepare ANFs with a well-defined and uniform structure. Through this novel deprotonation system, not only is the preparation time of 0.2 wt% ANFs greatly shortened to 26 min (a tenth of the time of the state-of-the-art technology) but also the production of ANFs with high concentration (4.0 wt%) and in large amounts (1500 mL) can be realized within several hours. Importantly, the deprotonation process of Kevlar fibers as well as the formation mechanism and structural restoration of ANFs were studied by in situ characterization methods. In addition, the controlled preparation of ANF aerogels with diverse microstructures was realized by the structural restoration of ANFs under different protic solvents and subsequent lyophilization, and the physical properties of ANF aerogels were investigated. Significantly, the various Kevlar products and ANF aerogels both can be rapidly and highly efficiently dissociated to ANFs, undoubtedly demonstrating the proof-of-concept for recycling of waste aramid products and closed-loop recycling of ANF-based materials. Therefore, this work not only offers a better understanding of the mechanism of both the deprotonation of aramid fibers and the restoration of ANFs, but also provides a highly feasible, highly efficient and cost-effective recycling strategy of waste aramid products and ANF-based materials.