两性离子聚合物合成及盐敏机理研究

Study on the Synthesis and Salt Sensitivity Mechanism of Zwitterionic Polymers

利用两性离子单体在高盐环境中分子链更舒展的特殊性能,即反聚电解质效应,设计合成一种两性离子聚合物。该聚合物以两性离子功能单体和丙烯酰胺(AM)合成,优选1,4-丁磺酸内酯与N-(3-二甲基丙基)甲基丙烯酰胺合成的甲基丙烯酰胺丙基-N,N-二甲基丁磺酸盐(NS-2)为功能单体。优化聚合物合成条件为:反应温度40℃,溶液pH值=7,引发剂质量分数为0.05%,单体占溶液总质量的40%,反应时间10 h,m(AM)∶m(NS-2)=9∶1。进而利用流变仪探究盐浓度对聚合物溶液黏弹性的影响,并用动态光散射法探究不同盐浓度和盐离子类型下分子形态和展布规律,结果表明随着盐浓度增加合成聚合物的黏弹模量和复合模量增大,分子链在高盐环境下呈现更舒展的形态和展布,流体力学半径增大,链内/链间的疏水缔合作用增强,分子链间相互缠绕出现大尺寸缔合峰,且盐离子特异性影响程度表现为Mg^(2+)>Ca^(2+)>Na^(+)。

This article utilizes the special performance of zwitterionic monomers in high salt environments,namely the anti electrolyte effect,to design and synthesize a zwitterionic polymer.The polymer is synthesized from zwitterionic functional monomers and acrylamide(AM),with the preferred functional monomer being methylacrylamide propyl-N,N-dimethylbutylsulfonate(NS-2)synthesized from 1,4-butylsulfonic acid lactone and N-(3-dimethylpropyl)methylacrylamide.The optimized conditions for polymer synthesis are:reaction temperature of 40℃,solution pH=7,initiator mass fraction of 0.05%,monomer accounting for 40% of the total solution mass,reaction time of 10 hours,AM∶NS-2 mass ratio of 9∶1.Furthermore,a rheometer was used to investigate the effect of salt concentration on the viscoelasticity of polymer solutions,and dynamic light scattering was used to investigate the molecular morphology and distribution patterns under different salt concentrations and salt ion types.The results showed that as the salt concentration increased,the viscoelastic modulus and composite modulus of the synthesized polymer increased,and the molecular chains exhibited a more relaxed morphology and distribution in high salt environments.The fluid dynamics radius increased,and the hydrophobic binding between chains/within chains was enhanced.Large size binding peaks were observed in the entanglement between molecular chains,and the degree of salt ion specific influence was manifested as Mg^(2+)>Ca^(2+)>Na^(+).