INTERPENETRATING ORGANOMETALLIC POLYMER NETWORKS BASED ON POLY(DIMETHYLACRYLAMIDE-CO-METHYLENEBISACRYLAMIDE) - SYNTHESIS AND ISEC-ESR CHARACTERIZATION

Poly(N,N-dimethyl acylamide) re sins, cross-linked up to 8 mol % with methylenebisacrylamide, have been investigated in the swollen state (d ichloromethane, DCM, and tetrahydrofuran, THF) by means of inverse ste ric exclusion chromatography (ISEC) and electron spin resonance spectr oscopy (ESR). Their behavior has been evaluated on the basis of a phys icochemical model, which was previously developed to describe the beha vior of the same materials in water. This model is based on the assump tion that the swollen resins can be depicted as concentrated viscous p olymer solutions. In DCM, this hypothesis still holds for the relative ly lightly cross-linked swollen gels, while it is not acceptable when the crosslinking degree is higher than 4 mol %. When THF is used as th e liquid medium; the investigated resins do not fully swell, and the s pin probe employed for the ESR measurements is adsorbed from the liqui d phase onto the polymer chains. Therefore, the characterization of th ese polymers swollen in THF did not give unambiguous results. The same ISEC-ESR combined approach has been exploited to study the swelling b ehavior of several sequential interpenetrating organometallic polymer networks. These materials were obtained upon dispersion of different a mounts of an organometallic, cross-linked -dimethylacrylamide/methylen ebisacrylamide)-inside a poly(N,N-dimethylacrylamide) resin, cross-lin ked with methylenebisacrylamide (4 mol %). Th, introduction of the ''g uest'' copolymer into the tridimensional network of the resin has been found to increase the swelling volume of the ''host'' matrix.