Computational analysis of short-range surface-directed polymerization-induced phase separation

The conventional off-critical polymerization-induced phase separation (PIPS) of binary mixtures leads to the fabrication of droplet-type structure. However, the presence of a surface preferably attracting one of the components while phase separation by spinodal decomposition is occurring can change the configuration of surface energy and result in the formation of wetting layer(s) adjacent to the wall. Farther from the wall, droplets can still form. The method is called surface-directed spinodal decomposition. The method is applicable in the fabrication of materials with layered morphology and may lead to the enhancement of the surface physical characteristics of mixtures. The current paper theoretically studied short-range surface-directed PIPS of a solvent/monomer mixture. The results showed the average diameter of particles in the bulk in the intermediate stage of phase separation grew with time by power-law function proportional to t(*alpha), and the exponent (alpha(ave) approximate to 0.3) was found close to the Lifshitz-Slyozov growth exponent (1/3) for the diffusivities studied in this paper. The time evolution of the thickness of the wetting layer was found to be logarithmic. The effects of the parameters such as diffusion coefficient, surface potential, and temperature gradient on the morphology development by the short-range surface-directed PIPS technique are discussed in this paper.