Zhang Panpan, Zhang Xuan, Kreuzer Lucas P, Schwaiger Dominik M, Lu Min, Cubitt Robert, Zhong Qi, Müller-Buschbaum Peter
Key Laboratory of Intelligent Textile and Flexible Interconnection of Zhejiang Province; Key Laboratory of Advanced Textile Materials & Manufacturing Technology, Ministry of Education, Zhejiang Sci-Tech University, 310018 Hangzhou, China.
Department of Physics, Chair for Functional Materials, TUM School of Natural Sciences, Technical University of Munich, James-Franck-Street 1, 85748 Garching, Germany.
Langmuir. 2023 Aug 1;39(30):10464-10474. doi: 10.1021/acs.langmuir.3c00905. Epub 2023 Jul 17.
The kinetics of UV radiation-induced fast collapse and recovery in thermally cycled and rehydrated light- and thermo- double-responsive copolymer films of poly(oligo(ethylene glycol) methyl ether methacrylate--6-(4-phenylazophenoxy)hexyl acrylate), abbreviated as P(OEGMA--PAHA), are probed by neutron reflectivity (NR). The copolymer film is exposed to a thermal treatment starting at a temperature of 60 °C, which is well above its transition temperature (TT = 53 °C) before the temperature is rapidly decreased from 60 to 23 °C. Based on the applied protocol, the initially collapsed P(OEGMA--PAHA) film is rehydrated due to the switching of polymer chains from a more hydrophobic to a more hydrophilic state when the temperature falls below its TT. The whole rehydration process can be divided into 3 stages: DO absorption, chain rearrangement, and film reswelling. After rehydration, the thermally cycled P(OEGMA--PAHA) film is switched by UV irradiation via setting the UV radiation on and off. Considering the UV-induced collapse and recovery, both processes are slower than those observed in freshly hydrated films without any thermal stimulus history. Therefore, the experienced thermal history of the film should be considered in the design of sensors and detectors based on double-responsive copolymer films.
通过中子反射率（NR）研究了聚（寡聚（乙二醇）甲基醚甲基丙烯酸酯-6-（4-苯基偶氮苯氧基）己基丙烯酸酯）（简称为P（OEGMA-PAHA））的热循环和再水化的光热双响应共聚物薄膜中紫外线辐射诱导的快速塌陷和恢复动力学。共聚物薄膜在60°C的温度下开始进行热处理，该温度远高于其转变温度（TT = 53°C），然后温度从60°C迅速降至23°C。根据所应用的方案，当温度降至其TT以下时，最初塌陷的P（OEGMA-PAHA）薄膜会因聚合物链从更疏水状态转变为更亲水状态而重新水化。整个再水化过程可分为三个阶段：DO吸收、链重排和薄膜再膨胀。再水化后，通过打开和关闭紫外线辐射，对热循环的P（OEGMA-PAHA）薄膜进行紫外线照射切换。考虑到紫外线诱导的塌陷和恢复，这两个过程都比在没有任何热刺激历史的新鲜水合薄膜中观察到的过程要慢。因此，在基于双响应共聚物薄膜的传感器和探测器设计中应考虑薄膜经历的热历史。
