Differences in association behavior of isotactic and atactic poly(methacrylic acid)

作者：Sitar Simona; Aseyev Vladimir; Kogej Ksenija^*

来源：Polymer, 2014, 55(3): 848-854.

DOI：10.1016/j.polymer.2014.01.007

• Isotactic poly(methacrylic acid)
• Light scattering
• Aggregation

In this paper we show by light scattering techniques that polymer tacticity introduces an opposite association behavior in the case of aqueous solution of poly(methacrylic acid) in the presence of 0.1 M NaCl. Aggregates of highly stereoregular isotactic poly(methacrylic acid), iPMA, are disrupted by shear and gradually reform in solution at rest, whereas those of the usual atactic form, aPMA, multiply as a result of mechanical stress (phenomenon of negative thixotropy) and gradually decrease in number after its cessation. The aggregates have characteristics of microgel particles and may act as precursors for temperature induced gelation at higher concentrations. According to the shape parameter rho (similar to 0.6 and similar to 0.70 for iPMA and aPMA, respectively) iPMA aggregates have a denser core than aPMA ones. Additional differences between both isomers are demonstrated at higher degrees of neutralization, alpha(N), through the analysis of the polyelectrolyte slow mode, which was identified for all alpha(N) > 0.25 with iPMA but only for alpha(N) = 1 with aPMA.

• 出版日期2014-2-12