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61.
Guochen Wang Weiping Xu Yanxin Zhang Dong Chen Yuhong Ma Changtong Song Wantai Yang 《应用聚合物科学杂志》2024,141(13):e55172
Dynamic B O bonds are often applied to fabricate reversible-cross-linking and reprocessable polymer networks due to their high thermodynamic stability and kinetic tunability. However, it is still difficult to tailor boronic ester polymers, which have both excellent mechanical and self-healing properties in the absence of external stimuli. To address the above challenge, a range of room-temperature self-healable vitrimers are prepared by the reactions of various poly(vinyl hydroxyalkyl ether-alt-dialkyl maleate) copolymers and 1,4-phenyldiboronic acid. The dynamic cross-linking networks offer the as-prepared vitrimers superior mechanical properties and thermostability. Because of the presence of dynamic boronic ester bonds, the networks also demonstrated self-healing (the tensile strength recovered to 83% after 3 days at room temperature) and reprocessing capabilities (no significant change in tensile strength after thrice process recycles). Moreover, the vitrimers have potential as promising damping materials with wide temperature windows around room temperature. For example, the vitrimer of poly(ethylene glycol monovinyl ether-alt-dibutyl maleate) and 1,4-phenyldiboronic acid demonstrates its tanδmax 1.18, Tg = 6.2°C and effective damping temperature range is from −16.4 to 48.5°C. 相似文献
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Light-responsive cellulose nanocrystal@polydopamine (CNC@PDA) modified fluorinated polyacrylate was synthesized by Pickering emulsion polymerization with light-responsive block copolymer modified CNC@PDA as stabilizer. The epoxy groups in poly(acrylic acid-co-acrylamide)-b-poly(glycidyl methacrylate)-b-poly(hexafluorobutyl acrylate-co-coumarin) amphiphilic triblock copolymer reacted with the hydroxyl and amino groups on the surface of CNC@PDA to form the modified CNC@PDA. The successful preparation of modified CNC@PDA was confirmed by means of FT-IR, XRD, TG, UV–Vis, surface tension measurement, and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that the modified CNC@PDA had light-responsive and amphiphilic properties, and could be used as stabilizer to form stable Pickering emulsion. And the influence of modified CNC@PDA dosage on emulsion polymerization and film performance was systematically studied. The latex particle size decreased initially with increasing modified CNC@PDA dosage, from 0.6 to 1.0 wt%, and then increased. The mechanical, self-healing, and water–oil repellent properties of film were enhanced initially with increasing modified CNC@PDA dosage, from 0.6 to 1.0 wt%, and then declined. Atomic force microscope confirmed that the latex film had a rough surface. Moreover, the latex film comprising 1.0 wt% modified CNC@PDA presented not only high tensile strength (4.92 MPa), large elongation at break (657.70%), and superior oil/water repellency but also excellent self-healing property. 相似文献
63.
顾欣 《电信工程技术与标准化》2003,(8):74-81
本文系统地阐述了IP over DWDM的分层模型、关键技术,并对IP over DWDM技术在城域网中的应用和发展前景进行了介绍。 相似文献
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介绍了三明地区各县市至地调光缆线路的建设方案和光传输平台总体方案。利用SDH环形网络具有自愈能力的优点,详细分析了组网技术及复用段保护机制。说明了三明地区农网光纤通信系统的组网概况,及在光纤传输平台上配置SDH复用保护段设备的情况。 相似文献