Aggregates of Isotactic Poly(methacrylic acid) Chains in Aqueous CsC1 Solutions: a Static and Dynamic Light Scattering Study

作者：Hocevar Katarina; Sitar Simona; Kogej Ksenija^*

来源：Acta Chimica Slovenica, 2015, 62(3): 546-554.

• isotactic poly(methacrylic acid)
• light scattering
• hydrodynamic radius
• shape parameter
• aggregation
• poly-electrolyte slow mode

Properties of isotactic polymethacrylic acid, iPMA, chains were studied at 25 degrees C in aqueous solutions at various CsC1 concentrations, c(s) (= 0.05-0.20 M), in dependence on degree of neutralization of the polyion's carboxyl groups, a, using static, SLS, and dynamic light scattering, DLS, measurements. It was demonstrated that iPMA chains with a, somewhat above the solubility limit of iPMA in aqueous solutions (in the present case at alpha(N)=0.27) are strongly aggregated. The size of the aggregates increases with increasing cs, whereas the shape parameter, rho, is approximately constant (rho approximate to 0.6), irrespective of cs. The low rho value suggests that the aggregates have characteristics of microgel particles with a dense core surrounded by a less dense corona. The diffusion of iPMA chains was investigated also at higher alpha(N), up to alpha(N)= 1. The polyion slow mode arising from electrostatic interactions between charged chains was observed for alpha(N), exceeding the value 0.27 even at the highest c(s) (= 0.20 M). The diffusion coefficients for the show mode were nearly independent of alpha(N) and c(s) at the studied polymer concentration.

• 出版日期2015