CHARACTERIZATION OF FILM FORMATION FROM DIRECT MINI-EMULSIFIED POLYSTYRENE LATEX-PARTICLES VIA SANS

Mini-emulsified latexes of anionically polymerized deuterated and protonated polystyrene (DPS = 185 000, HPS = 200 000) were prepared by direct mini-emulsification. Films containing 6 % deuterated particles were annealed at 144-degrees-C for various periods of time. The average depth of penetration of the deuterated polystyrene chains and tensile strength buildup were characterized during the course of annealing. When the present results were compared with those of the conventional emulsion polymerized system, the directly mini-emulsified latex had greater interdiffusion rates and higher tensile strength than the emulsion polymerized latex system at similar annealing times. This difference may be due to the polydisperse nature of the molecular weight distribution and/or to the large and polar chain end groups of the emulsion polymerized system. The present system shows a minimum depth of penetration for full tensile strength of around 105-115 angstrom, comparable to 0.81 times the weight-average radius of gyration, R(g)w, of the whole polystyrene chain, while the tensile strength buildup was dependent on the annealing time to the 0.51 +/- 0.05 power. The tensile strength curve as a function of annealing time goes through a maximum and then levels off. Finally, the diffusion coefficient from the SANS data was (4.7 +/- 1.0) x 10(-16) cm2/s at the scattering vector Q = 0.0067 angstrom-1.