POLYMER-POLYMER COMPLEXATION BETWEEN POLY(MONOMETHYL ITACONATE) AND POLY(VINYLPYRIDINE)S

Polymer-polymer hydrogen-bonded complexes of poly(monomethyl itaconate) with poly(2-vinylpyridine) and poly(4-vinylpyridine) were studied. Several solvents have been assayed for these systems: methanol, methylformamide and binary mixtures (50/50) of methanol with water, tetrahydrofuran, dimethylformamide and dimethylacetamide. In all cases, instantaneous precipitate formation was observed after mixing the solutions of poly(monomethyl itaconate) and poly(vinylpyridine)s. Polymer complexes prepared from methanol solutions show different stoichiometries depending on the feed composition, but that found in most cases was 3:2 of monomethyl itaconate:vinylpyridine repeat units. Complexes are insoluble in all the tested solvents; only fresh precipitate may be solubilized by increasing the pH of the solution. Complex formation is observed even when the density of pyridine groups is reduced to 25% by copolymerization with styrene. Differential scanning calorimetry analyses do not show a glass transition temperature for poly(monomethyl itaconate) polymer complexes; only a wide degradation peak was observed. Thermogravimetric experiments corroborate that the thermal degradation behaviour does not differ substantially from that of the pure components. In these conditions, Fourier-transform infra-red spectroscopy was used to study their hydrogen-bonding interactions. The infra-red spectra corresponding to polycomplexes clearly show evidence of hydrogen bonding between the components and there seems to be some evidence of partial pyridine protonation.