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

Mini-emulsified latexes of anionically polymerized deuterated and prot onated polystyrene (DPS = 185 000, HPS = 200 000) were prepared by dir ect mini-emulsification. Films containing 6 % deuterated particles wer e annealed at 144-degrees-C for various periods of time. The average d epth of penetration of the deuterated polystyrene chains and tensile s trength buildup were characterized during the course of annealing. Whe n the present results were compared with those of the conventional emu lsion polymerized system, the directly mini-emulsified latex had great er interdiffusion rates and higher tensile strength than the emulsion polymerized latex system at similar annealing times. This difference m ay be due to the polydisperse nature of the molecular weight distribut ion and/or to the large and polar chain end groups of the emulsion pol ymerized system. The present system shows a minimum depth of penetrati on 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 o n 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 angs trom-1.