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以N,N-二甲基丙烯酰胺(DMA)和双丙酮丙烯酰胺(DAAM)为共聚单体,在水溶液中采用常规自由基聚合以K_2S_2O_8-Na_2SO_3双氧化还原体系为引发剂,合成了一系列具有最低临界溶解温度(LCST)的温敏性聚合物P(DMA-co-DAAM).采用紫外可见分光光度计、动态光散射、芘荧光探针法和变温核磁共振氢谱等多种手段研究共聚物在不同温度下的溶液结构,结果表明共聚物P(DMA-co-DAAM)具有明显的热致缔合行为,在低温下聚合物以单链形式溶解,温度升高超过LCST之后由于P(DMA-co-DAAM)分子链上DAAM侧基发生亲水-疏水性变化,部分疏水链段缔合形成微相分离的胶束聚集体.进一步的研究还表明通过改变共聚物组成和溶液浓度能够有效调节共聚物溶液的缔合转变温度,共聚物P(DMA-co-DAAM)的LCST值与DAAM含量成很好的线性关系,DAAM含量越高LCST温度越低.采用常规自由基聚合所带来的链间异质性以及分子量的多分散性等特点并没有显著影响共聚物P(DMA-co-DAAM)的温敏性.
N, N-dimethylacrylamide (DMA) and diacetone acrylamide (DAAM) were used as comonomers to synthesize a series of K 2 S 2 O 8 -Na 2 SO 3 double redox systems by conventional radical polymerization in aqueous solution. The thermosensitive polymer P (DMA-co-DAAM) with the lowest critical solution temperature (LCST) was studied by means of UV-visible spectrophotometer, dynamic light scattering, pyrene fluorescence probe and NMR spectroscopy. The results showed that the copolymer P (DMA-co-DAAM) had obvious thermal-induced association behavior. At low temperature, the polymer dissolved in single-stranded form. When the temperature was increased beyond LCST, P (DMA-co-DAAM), hydrophilic and hydrophobic changes occurred on the side groups of DAAM, and some hydrophobic segments were associated to form micellar aggregates with micro-phase separation.Further studies also showed that by changing the copolymer composition and solution concentration The LCST value of copolymer P (DMA-co-DAAM) has a good linear relationship with the content of DAAM. The higher the DAAM content is, the lower the temperature of LCST is. Conventional free radical polymerization The resulting heterogeneity between chains and molecular weight Polydispersity characteristics did not significantly affect the copolymer P (DMA-co-DAAM) temperature sensitive.