Mechanism of Romascone (R) release from hydrolyzed vinyl acetate nanoparticles: thermogravimetric method

The evaporation kinetics of pure Romascone(R) (methyl 2,2-dimethyl-6-methylene-1-cyclohexanecarboxylate) and Romascone(R) when mixed with vinyl acetate (VAc) nartoparticles have been determined by using thermogravimetric analysis. For pure Romascone(R), the evaporation rate follows an Arrhenius dependence with temperature. When Romascone(R) is mixed with VAc nanoparticles, two evaporation mechanisms are identified depending on the presence of comonomer and cross-linking degree. (a) Evaporation limited by the presence of non-interactive nanoparticles. The evaporation rate is governed by the evolution of the equilibrium vapor pressure that depends on the volume fraction of volatile molecules. (b) Evaporation limited by the diffusion of volatile molecules through a polymeric particle wall. Since the diffusion depends on the physical state or structure of the polymeric nanoparticle phase, the volume fraction of volatile molecules is a determinant parameter. Furthermore, a sudden modification in the evolution of the diffusion coefficient with volatile volume fraction gives rise to discussion on phase transition. Copyright (C) 2006 John Wiley & Sons, Ltd.