Molecular Weight Effect on the Quaternization of Poly(4-vinylpyridine) with Alkylbromide

Abstract

The objective of this work is to study the influence of molecular weight on the quaternization of poly(4-vinylpyridine) (P4VP) with octyl and dodecyl bromide. The P4VP with different molecular weight was synthesized by radical polymerization. The molecular weight was determined by viscosimetric and light scattering. A set of copolymers containing the poly(4-vinylpyridine) of different molecular weights quaternized with octyl and dodecyl bromide (C8Br and C12Br) were prepared. In order to determine the solubility limit of each copolymer; phase diagrams were established according to the water percentage in the mixture water-ethanol. Empiric laws for the rate maximum (Tmax) and Mw were proposed. We have considered six P4VP samples in wide intervals of molecular weights: 0.75.104 to 94.104 g/mol. The ratio between the high size and the small size is 106.7. The maxima rate of quaternization (Tmax) and the initial constants rate k0 increase with P4VP molecular weights. Critical time for the quaternization kinetics is 360 h, which is independent of Mw. The length of alkyl chain from C8 does not affect the quaternization kinetics. The solubility of copolymers in water decreases with macromolecular weight,which is not the case for P4VP homopolymer.