梳型丙烯酰胺共聚物在水溶液中的缔合结构

采用荧光探针研究了丙烯酰胺(AM)/4-乙烯苄基辛烷基酚聚氧乙烯(10)醚(VBPOE)/2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)梳型共聚物(PAVA)在水溶液中的疏水缔合微结构。结果发现,在纯水和盐水溶液中,随聚合物浓度的增大,疏水微区的数量和非极性明显增加,但当PAVA浓度高于0.20 g/dL时,疏水微区的非极性趋于恒定,而且0.5 g/dLNaCl的加入对I1/I3值(I1/I3的变化可以表征疏水微区是否形成以及监测疏水缔合微区的变化)的影响极小,这证实了分子链在盐水中的构象仍然较伸展,使得PAVA在盐水中也能形成连续的缔合结构,从而赋予聚合物良好的抗盐和增粘性能。随着盐浓度的增加,缔合微结构的非极性变化不大,但其紧密度和数量增加,Ie/Im值持续增大。

Associating Structures of Comb-Like Acrylamide-Based Terpolymers in Aqueous Solutions

The hydrophobically associating microstructures in aqueous solutions were measured by the fluorescent probe for a comb-like terpolymers(PAVA) of acrylamide(AM),sodium 2-acrylamido-2-methylpropane sulphonate(NaAMPS) and p-vinylbenzyl-terminated octylphenoxy poly(ethylene oxide)(VBPOE,polymerization number: 10).The results show that the sizes and non-polarity of hydrophobic microdomains increase remarkably with increasing polymer concentration in unsalted and brine solutions.However,at the polymer concentrations higher than 0.20 g/dL,the non-polarity of hydrophobic microdomains tends to constancy and the I1/I3 value(the change of I1/I3 value can characterize the formation of hydrophobic micro-domains and monitor their change.)changes slightly with the addition of 0.5 g/dL NaCl.This suggests that the polymer chains are comparatively extended.Consequently,the continuous associating structures are also formed in brine solutions,which result in good thickening and resistance to salt for PAVA.As NaCl concentration increases,the non-polarity of associating microstructures increases slowly.However,the compact degree and sizes of these microstructures increase,leading to a continuous rise in Ie/Im.