Polymer‐solvent interactions in mixed solvents, 1. Isotactic, syndiotactic and atactic poly(methacrylic acid) in water/2‐chloroethanol mixtures

Abstract

The viscosimetric behaviour and the preferential solvation of syndiotactic, isotactic, and atactic poly(methacry1ic acid), [poly(l-carboxy-1-methylethylene)] are studied in water/2chloroethanol mixtures. The experimental results show that the preferential solvation of the polymer is strongly dependent on its local conformation. In the case of the syndiotactic sample, a close correlation has been established between the compact structure t coil conformational transition and the variation of the preferential and absolute solvation of the polymer by 2-chloroethanol, asserting the importance of hydrophobic interactions in the stabilization of the compact structure. Experimental data concerning the isotactic sample suggest the existence of an "inverse compact structure" in 2-chloroethanol-rich mixtures.

Conformational studies on poly(ethacrylic acid) in aqueous salts by potentiometric, viscometric, optical and1H-NMR measurements

“…Its potentiometric, viscometric and optical titrations in aqueous salts have shown the pH-induced conformational transition similar to those of the maleic acid copolymers [12][13][14][15]. Results of solubility measurements [16] of hydrophobic dyes into PMA at low degree of ionization a of carboxyl groups and preferential binding [17] of organic solvents to PMA in aqueous solutions are consistent with the conclusion of the existence of the compact form at low a stabilized by hydrophobic interaction between methyl groups, although some authors have emphasized importance of hydrogen bond formation for stabilization of the acid form of PMA [18,19]. Poly(ethacrylic acid) (PEA) may also be an important substance for studying the compact form and the conformational transition of the hydrophobic polyelectrolyte from a standpoint of comparison with PMA.…”