Hofmeister Effect on Thermo-responsive Poly(N-isopropylacrylamide)Hydrogels Grafted on Macroporous Poly(vinyl alcohol) Formaldehyde Sponges  

作　　者：Kai Shi Di Sha Jiu-Duo Xu Xu Yang Bao-Long Wang Yan-Xiong Pan Xiang-Ling Ji 

机构地区：[1]State Key Laboratory of Polymer Physics and Chemistry,Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China [2]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Journal of Polymer Science》2020年第3期257-267,I0006,共12页高分子科学（英文版）

基　　金：financially supported by Foundation of State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry

摘　　要：In this work,the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature(LCST)of the macroporous thermo-responsive poly(N-isopropylacrylamide)grafted poly(vinyl alcohol)formaldehyde(PVF-g-PNIPAM)hydrogels are investigated with differential scanning calorimetry(DSC).Four kinds of anions with strong hydration,including CO3^2–,SO4^2–,S2 O3^2–,and F^–,and four kinds of anions with weak hydration,including Br^–,NO3^–,I^–,and ClO4^–,and Cl^–as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM.On the one hand,the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water.On the other hand,the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains,which results in the increase of LCST values.In addition,the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.In this work, the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature（LCST）of the macroporous thermo-responsive poly（N-isopropylacrylamide） grafted poly（vinyl alcohol） formaldehyde（PVF-g-PNIPAM） hydrogels are investigated with differential scanning calorimetry（DSC）. Four kinds of anions with strong hydration, including CO32–, SO42–, S2 O32–, and F–, and four kinds of anions with weak hydration, including Br–, NO3–, I–, and ClO4–, and Cl– as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM. On the one hand, the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water. On the other hand, the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains, which results in the increase of LCST values. In addition, the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.

关 键 词：Hofmeister effect THERMO-RESPONSIVE PVF-g-PNIPAM Hydroxyl groups Network structure 

分 类 号：TQ427.26[化学工程]