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用溶液聚合方法合成了线型聚(N-异丙基丙烯酰胺-co-N-乙烯基吡咯烷酮)共聚物,通过弹性光散射(elastic light scattering,ELS)、荧光光谱与动态光散射研究了共聚物水溶液分子链可逆聚集的温度和时间依赖性.研究表明,升温时,ELS强度增加,分子链聚集;降温时,ELS强度降低,聚集的分子链解离.荧光光谱研究表明,分子链在升温时发生了疏水缔合相互作用,从而使得分子链聚集体荧光强度增加,降温时分子链发生解离,使荧光强度减弱.动态光散射测得升温时聚合物的平均流体力学半径在最低临界溶解温度(LCST)时急剧增大,而后减小,降温过程的变化与升温相反.此外,从弹性光散射容易得出,共聚物因含有亲水性NVP而使其LCST高于PNIPAM均聚物.可见,通过弹性光散射、荧光光谱和动态光散射得到的共聚物分子链在水溶液中的可逆聚集行为是一致的.
Linear poly (N-isopropylacrylamide-co-N-vinylpyrrolidone) copolymers were synthesized by solution polymerization. The effects of copolymerization The temperature and time dependence of molecular chain of aqueous solution are reversible. The results show that the strength of ELS increases and the molecular chain accumulates when the temperature rises, and the strength of ELS decreases and the aggregated molecular chain dissociates when the temperature is lowered. Fluorescence spectroscopy studies show that the molecular chain is heated at elevated temperature The hydrophobic interaction occurs, so that the molecular chain aggregates increased fluorescence intensity, molecular chain dissociation occurs when cooling, so that the fluorescence intensity decreased.Analysis of dynamic light scattering polymer average hydrodynamic radius at the lowest critical solution When the temperature (LCST) increases sharply, and then decreases, the change of the cooling process is opposite to that of the temperature rising.Furthermore, it can be easily deduced from the elastic light scattering that the copolymer has higher LCST than the PNIPAM homopolymer due to the hydrophilic NVP. It can be seen that the reversible aggregation behavior of copolymer chains in aqueous solution obtained by elastic light scattering, fluorescence spectroscopy and dynamic light scattering is consistent.