Authors: Qiujing Dong Meijuan Qian Chunhua Luo
Publish Date: 2016/01/26
Volume: 23, Issue: 2, Pages: 33-
Abstract
The phase separation behavior and fluorescence properties of linear PNIPAM with chalcone side groups PNIPAMC in watercononsolvent systems were studied as a function of solvent composition x and temperature It was found that PNIPAMC exhibited a single lower critical solution temperature LCST in water–methanol water–acetone and water–tetrahydrofuran the addition of organic solvents initially decreased the phase separation temperature and a further addition increased it rapidly The minimum LCST was −8 °C for the mole fraction of methanol x methanol ≈ 031 17 °C for x acetone ≈ 014 and −2 °C for x tetrahydrofuran ≈ 013 However in water–ethanol solution a simultaneous LCST and upper critical solution temperature UCST existed for lower and higher ethanol concentrations respectively and the phase separation temperature decreased drastically with increasing ethanol concentrations Furthermore the solvent compositionsensitive and temperaturesensitive fluorescence properties of PNIPAMC were investigated The results showed that the fluorescence emission wavelength λmax underwent a blue shift and the intensity increased with the addition of a small amount of organic solvent With further addition of organic solvent λmax and intensity were almost not changed However when the content of organic solvent exceeded a critical value such as x methanol 017 λmax blueshifted and the intensity increased with the increase of organic solvent At low content of organic solvent λmax decreased greatly and the intensity increased rapidly as the temperature was raised from 20 °C to 50 °C because phase separation occurred when the temperature was elevatedThis research work was supported by the National Natural Science Foundation of China 50903018 Natural Science Foundation for High School of Anhui Province KJ2014A192 2014KJ014 and Support Plan for Young Elite Talents of High School of Anhui Province gxyqZD2016191
Keywords: