Poly‐<i>n</i>‐Hexyl methacrylate. IV. Dilute solution properties by viscosity and light scattering

Abstract

Abstract Poly‐ n ‐hexyl methacrylate prepared by the emulsion technique was fractionated three times by the fractional precipitation procedure to obtain eight fractions. Relationships between viscosity‐ and weight‐average molecular weight were obtained in both an ideal solvent, isopropanol, and a nonideal solvent, methyl ethyl ketone. These relationships are represented by equations: The effect of the size of the pendant groups (‐methyl, ‐ethyl, n ‐butyl and ‐ n ‐hexyl ester) on the degree of extension of macromolecules in ideal solvents is discussed. It was found that initially as we progress from polymethyl to poly‐ n ‐butyl methacrylate the degree of flexibility of the macromolecule increases as the size of the pendant group increases. These results are believed to be due to the short‐range interference effect of the solvent molecule on the degree of free rotation of the macromolecule. However, it was found that poly‐ n ‐bexyl methacrylate chains have considerably greater chain extension than any of the other three polymers. This expansion of poly‐ n ‐hexyl methacrylate chains ia a result of the steric effect of large pendant units.