水溶性AM-St两亲嵌段共聚物的自乳化微乳液法合成

Synthesis of Water-Soluble Amphiphilic Block Copolymer by Self-Emulsifying Microemulsion Method

以分子量低、表面活性好的丙烯酰胺 (AM ) 苯乙烯 (St)两亲嵌段共聚物 (PAM b PSt)为大分子表面活性剂 ,配制了丙烯酰胺 苯乙烯微乳液共聚合体系 ;绘制了拟三元微乳液相图 ;从微乳液相图中选择了合适的共聚合体系 ,用自乳化微乳液共聚合法制得高分子量的两亲嵌段共聚物PAM b PSt。用FTIR及UV分析了产物的化学组成 ,用DSC表征了产物分子链的嵌段结构 ;用荧光探针法与旋转粘度法研究了产物PAM b PSt的疏水缔合性。结果表明 ,采用大分子表面活性剂同样可配制出O/W型微乳液共聚合体系 ,且仅使用 3g即可将 0 2 5 g疏水单体稳定地分散在水中 ,表现出高的乳化效率 ;而且这种新的自乳化微乳液体系 ,免去了去除表面活性剂的后处理纯化过程 ,可一步制得纯净的两亲嵌段共聚物 ;所制产物具有良好的疏水缔合性 ,表现出明显的增稠作用 ,其水溶液粘度为同质量分数 (ω(p) =0 5 % )的聚丙烯酰胺水溶液粘度的 5倍。

The microemulsion system for the copolymerization of acrylamide(AM) and styrene(St) was prepared using copolymer(PAM-b-PSt) of small molecular weight and good surface activity as macromolecular surfactant. The phase diagram of three components was drawn up, from which a suitable copolymerization system was selected and an amphiphilic block copolymer PAM-b-PSt with high molecular weight was synthesized by self-emulsifying microemulsion copolymerization. The composition of the copolymer was analyzed by FTIR and UV method, the block architecture was characterized by DSC, and the hydrophobic association behaviour of the copolymer was investigated by fluorescence probe technique and apparent viscosity measurement. The results show that the microemulsion copolymerization system of O/W type can also be prepared using macromolecular surfactant. Only 3 g of the macromolecular surfactant was enough to disperse 0.25 g St into water. The method has advantages of having high emulsification efficiency and avoiding purification processes of polymers to remove the surfactant. The pure copolymer PAM-b-PSt could be obtained in one step process. The product has excellent hydrophobic association behaviour and thickening property, and the viscosity of its aqueous solution is about 5 times higher than that of PAM aqueous solution under the same concentration(ω(p)=0.5%).