Smart materials that can dynamically modulate incident light provide a broad prospect for the development of smart windows. However, the absence of capability to create smart materials with rapid transmittance switchability and mechanical robustness has restricted the realization of self-defensive smart windows. Here, a solvatochromic alcogel designed by cellulose–polyacrylamide supramolecular configuration for developing a self-defensive smart window is reported. The alcogel with compact nano-bulge structures exhibits reversible and rapid switching of transparency between 85% and 5%, cycle time less than 8 s, and has strong mechanical robustness with elastic modulus of over 60 MPa. With this smart alcogel, the proposed self-defensive smart window not only shows real-time and reliable adjustment of transparency but also outputs a strong mechanical impact resistance of up to 42.8 kJ m −2 , 10 and 12 times higher than that of a normal glass and photochromic window, respectively. It is believed that this study will open new opportunities for both fabrication and application of biological gels in smart windows and intelligent devices.
In biomedicine fields, biofouling can easily occur on devices such as sensors and catheters, causing some iatrogenic infections, which menace the lives and health of patients greatly. Therefore, it is of great significance to solve the problems of bacterial infection on the surfaces of medical devices. In this paper, “self-defensive” and antifouling zwitterionic hydrogel coatings were prepared by network interpenetration of the hydrogel and the polymeric substrates. The zwitterionic polysulfobetaine methacrylate (PSBMA) hydrogel coatings resisted most of the bacteria to adhere on the substrates. When a few bacteria were lucky to escape the antifouling defense and adhered to the coatings, gentamicin sulfate (GS) would be released under the trigger of a weakly acidic environment caused by bacterial metabolism to kill these bacteria. Simultaneously, the coatings of the bacteria-adhering sites would be degraded by hyaluronidase secreted by these bacteria and peeled off to remove the bacteria and renew the antifouling surfaces. The antifouling properties and mechanism of the self-defensive behavior of the hydrogel coatings on polymeric substrates were investigated. Furthermore, the in vitro and in vivo antibacterial performances, as well as the biocompatibility of the coatings, were demonstrated. The results suggested that the self-defensive antifouling zwitterionic hydrogel coatings hold great potential to be used on the surfaces of polymeric medical devices.
Mingde Tong,Xinhao Shi,Tao Feng,Ying Dai,Pengfei He
To achieve the repeatability of aerospace thermal components, C/TaC‒SiC composites were fabricated. Cycle ablation and bending tests were carried out. After 3 × 60 s of ablation beyond 2100°C, the mechanical property retention rate was 80.9%. Interestingly, a reaction similar to “ouroboros ring,” in which the cyclic reactions of “TaC being oxidized to Ta 2 O 5 and Ta 2 O 5 being reduced to TaC,” occurred in the central ablation region of C/TaC‒SiC composites. On the one hand, the continuous generation of TaC could prevent liquid state Ta 2 O 5 from being blown off central ablation region, playing a similar role in “water and soil conservation.” On the other hand, liquid Ta 2 O 5 covered the surface of C/TaC‒SiC composites during ablation process, contributing to block the inward permeation of oxidized gases. In addition, novel “Grotto” structures were detected in the transitional ablation region of C/TaC‒SiC composites. The formation reason of the “Grotto” structure has also been discussed.
危险品化学品经营许可证（带存储）