文献类型：期刊文献

英文题名：Dual Thermoresponsive Aggregation of Schizophrenic PDMAEMA-b-PSBMA Copolymer with an Unrepeatable pH Response and a Recycled CO2/N2 Response

作者：Sun, Hui[1];Chen, Xiaolu[1];Han, Xia[1];Liu, Honglai[1]

机构：[1]East China Univ Sci & Technol, Sch Chem & Mol Engn, Key Lab Adv Mat, Shanghai 200237, Peoples R China

年份：2017

卷号：33

期号：10

起止页码：2646

外文期刊名：LANGMUIR

收录：;EI(收录号：20171203454487);WOS:【SCI-EXPANDED(收录号:WOS:000396639700020)】；

基金：The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China (nos. 21376073 and 91534103), the 111 Project of the Ministry of Education of China (no. B08021), and Fundamental Research Funds for the Central Universities of China.

语种：英文

外文关键词：Bubble formation - Emulsification - Block copolymers

摘要：A dual thermoresponsive block copolymer of p oly [2- ( dim ethylamino) ethyl methacrylate]-block-poly-(sulfobetaine methacrylate) (PDMAEMA-b-PSBMA) ex-hibited reversible schizophrenic aggregation behavior in water because of the upper critical solution temperature (UCST) of the PSBMA block and the lower critical solution temperature (LCST) of the PDMAEMA block. Both the UCST and LCST shifted to lower values with increasing DMAEMA/SBMA block ratios, which was ascribed to the hydrophobic/hydrophilic balance of both blocks. Because of the salt-sensitive PSBMA and pH-responsive PDMAEMA, the UCST and LCST values of PDMAEMA-b-PSBMA were codetermined by varying the salt concentrations and pH. Specifically, increasing the salt concentration resulted in a notable decrease in the UCST and a slight increase in the LCST due to the salt-induced screening of the electrostatic attractions of the PSBMA and salt-enhanced solubility of the PSBMA blocks, respectively. The LCST decreased with increasing pH because of the deprotonation of PDMAEMA, and the UCST first increased and then decreased with increasing pH. Besides, the copolymer with larger PDMAEMA content was more sensitive to pH. For the repetitive adjustment to thermoresponsive aggregation, repeated addition of acids and bases induced salt accumulation and diminished the switchability of pH, whereas repeated switching cycles were achieved by CO2/N-2 bubbling without introducing salt enrichment. The difference in HCl/NaOH titration and CO2/N-2 bubbling also existed in the switching cycles when PDMAEMA-b-PSBMA served as a stimulus-responsive emulsifier.