具有温度敏感和荧光特性的侧链查尔酮共聚物的研究

采用2,2′-偶氮二异丁腈作为引发剂,将N-异丙基丙烯酰胺和4-甲基丙烯酰氧基-4′-二甲氨基查尔酮单体,在四氢呋喃溶剂中通过自由基共聚制备了一系列具有溶剂和温度双重敏感荧光特性的侧链查尔酮共聚物,并通过红外光谱、核磁共振氢谱和紫外-可见光谱对其结构进行表征,通过吸光度法测定了共聚物中查尔酮单元的含量.研究了侧链查尔酮共聚物的温敏性以及溶剂极性和温度双重敏感的荧光特性.结果表明,侧链查尔酮共聚物是一类具有最低临界溶解温度(LCST)的温敏性聚合物,其LCST温度随着共聚物中查尔酮含量的增加而降低;随着溶剂极性的增加,侧链查尔酮共聚物的紫外-可见最大吸收波长红移,其荧光发光波长红移并且发光强度先增强后降低,具有溶剂极性敏感的荧光特性;同时对比侧链查尔酮共聚物水溶液低温和高温下的荧光,发现低温下几乎无荧光,高温下其荧光得到明显增强,其荧光具有可逆的温度"开/关"特性。

STUDY ON CHALCONE-CONTAINING COPOLYMERS WITH THERMOSENSITIVITY AND FLUORESCENCE PROPERTIES

A series of chalcone-containing copolymers with the solvent and temperature dual responsive fluorescence were synthesized by the radical copolymerization of N-isopropylacrylamide(NIPAM) and 4methacryloyloxy-4'-dimethylaminochalcone(DMAC) in THF solution using AIBN as initiator,and their structures were confirmed by FTIR,1H-NMR and UV-Vis spectroscopy.The chalcone content in the copolymer was determined by UV-Vis absorbance method.The thermosensitivity of chalcone-containing copolymers and their solvent and temperature dual responsive fluorescence were investigated.The results show that the assynthesized chalcone-containing copolymers are a kind of thermosensitive polymers with a lower critical solution temperature(LCST) and the LCST of the copolymer decreases with the increase of the chalcone content in the copolymer.With the increase of the solvent polarity,both the maximum absorption wavelength and the fluorescence emitting wavelength of the chalcone-containing copolymers red-shifts,and the intensity of fluorescence first increases,then decreases,which exhibits solvent polarity sensitive fluorescence properties.Comparing the fluorescence of the copolymer aqueous solution at different temperatures,it is found that at high temperature the fluorescence of the copolymer has been enhanced,which endows the chalcone-containing copolymers with the reversible temperature"on /off"fluorescence properties.