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. S everal solvents have been assayed for these systems: methanol, methylf ormamide and binary mixtures (50/50) of methanol with water, tetrahydr ofuran, dimethylformamide and dimethylacetamide. In all cases, instant aneous precipitate formation was observed after mixing the solutions o f poly(monomethyl itaconate) and poly(vinylpyridine)s. Polymer complex es prepared from methanol solutions show different stoichiometries dep ending on the feed composition, but that found in most cases was 3:2 o f monomethyl itaconate:vinylpyridine repeat units. Complexes are insol uble in all the tested solvents; only fresh precipitate may be solubil ized by increasing the pH of the solution. Complex formation is observ ed even when the density of pyridine groups is reduced to 25% by copol ymerization with styrene. Differential scanning calorimetry analyses d o not show a glass transition temperature for poly(monomethyl itaconat e) polymer complexes; only a wide degradation peak was observed. Therm ogravimetric experiments corroborate that the thermal degradation beha viour 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 c orresponding to polycomplexes clearly show evidence of hydrogen bondin g between the components and there seems to be some evidence of partia l pyridine protonation.