Poly(vinyl acetate-co-dibutyl maleate) latex films in the presence of grafted and post-added poly(vinyl alcohol)

We describe the synthesis and characterization of a series of poly(vinyl acetate-co-dibutyl maleate) [P(VAc-DBM)] latex particles (monomer molar ratio 10.6:1). One set of samples [high-M and M-250k SDS-P(VAc-DBM), gel content 50% and 0%] was prepared in the presence of an anionic surfactant sodium dodecyl sulfate. The other two sets of samples [high-M and M-250k PVOH-P(VAc-DBM)] were prepared in the presence of poly(vinyl alcohol) (PVOH). These polymers differ in gel content (50 and 0%) and the extent of PVOH grafting (30 and 15%). Polymer diffusion across cell boundaries in the latex films was monitored by fluorescence resonant energy transfer (ET) experiments. First, we examined M-250k samples in the presence of grafted and post-added PVOH. The presence of post-added PVOH (5%) causes a small but detectable retardation on the rate of polymer diffusion, whereas the presence of grafted PVOH (degree of grafting: 15%) significantly promotes the polymer diffusion rate. For the high-M P(VAc-DBM), the presence of post-added PVOH also retards the polymer diffusion. Strikingly, the presence of grafted PVOH (degree of grafting: 30%) in the high-M PVOH-P(VAc-DBM) promotes the polymer diffusion to such an extent that the diffusion was complete in the freshly prepared films. Our data also suggest that under our experimental conditions, the rate of P(VAc-DBM) diffusion increases with an increase of the degree of PVOH grafting. To confirm these results, we carried out fluorescence microscopy experiments to monitor the fate of PVOH in these latex films and found that in newly formed PVOH-P(VAc-DBM) films, the PVOH was either uniformly distributed in the P(VAc-DBM) matrix or the domains were too small to be resolved (i.e., < 0.5 mum). (C) 2004 Wiley Periodicals, Inc.