A TEMPERATURE AND pH DOUBLE SENSITIVE CHOLESTERIC POLYMER FILM FROM A PHOTOPOLYMERIZABLE CHIRAL HYDROGEN-BONDED ASSEMBLY  

作　　者：Feng-jin Chen 郭金宝 Ou-yu Jin 魏杰 

机构地区：[1]College of Materials Science and Engineering,Beijing University of Chemical Technology

出　　处：《Chinese Journal of Polymer Science》2013年第4期630-640,共11页高分子科学（英文版）

基　　金：supported by the National Natural Science Foundation of China (No. 50903004)

摘　　要：In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.

关 键 词：Cholesteric polymer film Reflection band Stimulus responsive Chiral hydrogen-bonded assembly. 

分 类 号：O631.3[理学—高分子化学] TB383.2[理学—化学]