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A novel light-induced shape-memory material based on poly(l-lactide)-poly(ethylene glycol) copolymer is developed successfully by dangling the photoresponsive anthracene group on the PEG soft segment selectively. For synthesis strategy, the preprepared photoresponsive monomer N,N-bis(2-hydroxyethyl)-9-anthracene-methanamine (BHEAA) is first embedded into PEG chains; then, we couple this anthracene-functionalized PEG precursor with PLA precursor to result in PLA-PEG-A copolymer. The composition of target product can be well-defined by simply adjusting the feed ratio. The chemical structures of intermediate and final products are confirmed by (1)H NMR. Differential scanning calorimetry analysis of material reveals that the PEG soft segment became noncrystallizable when 4% or more BHEAA is introduced, and this feature is beneficial to the mobility of anthracene groups in polymer matrix. The static tensile tests show that the samples exhibit rubberlike mechanical properties except for the PLA-dominant one. The reversibility of [4 + 4] cycloaddition reaction between pendant anthracene groups in PLA-PEG-A film is demonstrated by UV-vis. Eventually, the light-induced shape-memory effect (LSME) is successfully realized in PLA-PEG-A. The results of cyclic photomechanical tests also reveal that the content of PLA hard segment as well as photosensitive anthracene moieties plays a crucial role in LSME.

Currently, a variety of elastomers with a self-healing capacity and reprocessability have been developed by dynamic chemistry to extend the service life, increase the reliability of polymeric materials, and reduce the waste. However, it is still a large challenge to seek an appropriate dynamic interaction that may perfectly match the general performance of the target polymeric materials such as polyurethane. Herein, we report a poly-(thiourethane-urethane) (PTUU−N x ) elastomer containing dynamic thiourethane bonds prepared via a thiol−isocyanate click reaction, which is stable at room temperature, healable at moderate temperature, and reprocessable at high temperature. Importantly, it exhibits a mechanical strength similar to the polyurethane because of a very similar structure. The dynamic feature of PTUU−N x is demonstrated theoretically and experimentally to originate from the exchange of thiourethane bonds via the reversible generation of isocyanates and thiols. Most importantly, the thiourethane bond possesses a much lower bond dissociation energy than the urethane bond, which not only makes PTUU−N x elastomers easier to be reprocessed but also endows them with a desirable self-healing ability under moderate conditions. In addition, the optimized sample PTUU−N 2 is utilized to fabricate a conductive device by coating Ag glue on the elastomer surface and inserting the coated elastomer into a circuit, which displays a high self-healing efficiency, as the material recovers to its original mechanical property and conductivity. Therefore, these results not only indicate that the PTUU−N x elastomers have considerable potential for applications in intelligent electronic devices but also provide new ideas for developing new self-healing materials by applying the adaptable dynamic bond to the target polymers.

Lithium tetrafluoroborate (LiBF4) used as an electrolyte additive to improve the cycling performance of LiNi0.5Co0.2Mn0.3O2/graphite cell at higher operating voltage is investigated. With 1.0 wt% LiBF4 addition into the electrolyte, the capacity retention of lithium ion battery after 100 cycles was greatly improved from 29.2% to 90.1% in the voltage of 3.0 V–4.5 V. To understand the mechanism of the capacity retention enhancement at high voltage operation, the properties including the cell performance, the impedance behavior as well as the characteristics of the electrode interfacial properties are examined. It is found that LiBF4 was likely to participate in the formation of interface film on both electrodes. The improved performances of the cell are attributed to the modification of interface layer components on graphite anode and LiNi0.5Co0.2Mn0.3O2 cathode, which leading to lower the interfacial impedance.