Chain conformation and intramolecular crosslinking of poly(dimethylaminoethyl methacrylate-co-methyl methacrylate-co-butyl methacrylate) in the presence of mono- or dicarboxylic acids: a dilute solution viscometry study

In this study, intramolecular crosslinking and changes in the chain conformation of a methacrylate terpolymer i.e., poly(dimethylaminoethyl methacrylate-co-methyl methacrylate-co-butyl methacrylate) was traced in dilute solutions as a function of mono- or dicarboxylic acids concentration. Acetic acid was examined as the monocarboxylic acid but dicarboxylic acids were selected as a homologous series including oxalic, succinic and adipic acid. The polymer was dissolved in a solvent mixture consisting of acetone, ethanol and 1-propanol in 60:33.43:6.57 weight percent ratios, respectively. Viscometric data were obtained by dilute solution viscometry using an Ubbelohde capillary viscometer. Chain conformation parameters were determined using two empirical models consisting of Rao and Heller equations. According to the results, tertiary amine functional groups on the terpolymer backbone was protonated due to the reducing pH values after adding acetic acid, which in turn caused an increment in intramolecular repulsive forces induced by electrostatic charges. These repulsive forces expand the polymer coil to helix. Intramolecular crosslinking was observed using dicarboxylic acids when polymer concentrations were lower than the critical overlap concentration.