包合作用与质子化程度对聚(N-丙烯酰-N′-丙基哌嗪)浊点的影响

聚（N-丙烯酰-N′-丙基哌嗪）(PAcrNPP) 是一种pH和温度双重响应的均聚物，通过调节PAcrNPP溶液的pH值可以改变其质子化程度，随着质子化程度的增加高分子溶液浊点逐渐升高。我们测试了不同尺寸的环糊精(CD)对PAcrNPP浊点的影响，在相同摩尔浓度时，α-CD对高分子溶液浊点影响最大，而α-CD对浊点几乎没有影响。分别在pH 9.0和pH 7.4时测量了含有不同浓度的α-CD的PAcrNPP水溶液的浊点，不同pH条件下，PAcrNPP水溶液的浊点随α-CD浓度的增大而升高。并根据溶液中不同存在形式的PAcrNPP对浊点的贡献，推导了一个方程，从化学平衡的角度说明了环糊精的包合与质子化程度对浊点的共同影响。

Effects of Inclusion Complexation and Degree of Protonation on Cloud Point ofPoly(N-acryloyl-N′-propylpiperazine)

Poly (N-acryloyl-N'-propylpiperazine) (PAcrNPP) is a pH- and temperature-responsive homopolymer. Degree of protonation of PAcrNPP can be changed by adjusting pH of the solution. Cloud point of PAcrNPP increased with increasing degree of protonation. We investigated effects of different sizes of cyclodextrins (CD) on cloud point of PAcrNPP. It was found that α-CD showed a significant effect on cloud point of PAcrNPP while α-CD had almost no effect on its cloud point. At pH 9.0 and pH 7.4, we measured cloud points of PAcrNPP solutions containing different concentrations of α-CD. Cloud point of PAcrNPP solutions rises with increase of concentration of α-CD. Further more, we deduced an equation on the basis of contributions of different forms of PAcrNPP to cloud point. This equation describes the combined effect of complexation of CD and degree of protonation on cloud point from the viewpoint of chemical equilibrium.