Langmuir, Vol.15, No.1, 27-31, 1999
Microemulsions of a vinyl acetate 2-ethylhexyl acrylate monomer mixture
The microemulsion system containing vinyl acetate (VAc), 2-ethylhexyl acrylate (EHA), n-propanol (PrOH), water, and nonyl phenol ethoxylate with 25 mol of ethylene oxide (NPEO25) or the maleic monoester of NPEO25 (MEMNPEO25) was studied. It was established that the probability of microemulsion formation increases either in the presence of the surfactant or following the increase of the VAc concentration in the mixture of comonomer. The nonlinear modification of refractive indexes controlled by the organic (o) over aqueous (w) phase ratio and the changing of pyrene fluorescence spectra, of the viscosity of the system without surfactant, and of the conductivity in systems with MEMNPEO25, all demonstrate the formation of nanostructures assigned to the association of PrOH in water. Depending on composition, three types of microemulsion were evidenced: w/o, bicontinuous, and o/w. Owing to the higher reactivity of EHA, the copolymers obtained diminish after polymerization the number of homogeneous samples compared to that of homopolymers. The final conversions depend on the type of initial microemulsions.
Keywords:MICROPOROUS POLYMERIC MATERIALS;METHYL-METHACRYLATE;2-HYDROXYETHYL METHACRYLATE;FLUORESCENCE;SURFACTANT;SYSTEMS;WATER;COSURFACTANTS;PYRENE;ACID