Homology Violation in a Series of Amphiphilic Comb-Like Statistical Copolymers of N-Methyl-N-vinylacetamide and N-Methyl-N-vinylamine with Moderate Density of Grafting of Side Dodecyl Groups

Abstract

A series of water-soluble comb-like copolymers of N-methyl-N-vinylacetamide and N-methyl-N-vinylamine (MVAA‒со‒MVA) bearing hydrophobic dodecyl side groups С12Н25 has been investigated by means of molecular hydrodynamics (viscometry, translational diffusion, and analytical ultracentrifugation) in dilute solutions in 0.1 M NaCl, under conditions of suppression of the polyelectrolyte effects. The issues of homology of these amphiphilic copolymers have been considered. The viscometry data plotted as lnηr as function of c[η] have allowed to distinguish between macromolecules of the copolymers according to their hydrophobicity. Positive values of the second derivative B2 determined from the initial parts of these curves have served as a measure of hydrophobicity of the amphiphilic copolymers. The noticeable differences in the B2 values for different copolymers have shown that they do not form true homologous series. For the quasi-homologous series of the MVAA–со–MVAC12H25·HI copolymers with close values of B2, the Kuhn–Mark–Houwink–Sakurada relationships have been obtained and the equilibrium rigidity of the chains has been assessed using the modified Gray–Bloomfield–Hearst equation.