Network domain structure in phase-separating polymer solutions

Results from molecular dynamics simulations of phase separation in a quench ed polymer solution are presented for both two- and three-dimensional syste ms. Simulations clearly demonstrate the existence of a networklike pattern formation at an early to intermediate time regime for sufficiently dense po lymer solutions. This network structure, however, relaxes at late times as the minimization of the interface energy wins over the elastic stress of th e network. A crossover of domain growth exponent from a smaller value at in termediate times to the Lifshitz-Slyozov value of 1/3 at late times is seen in three-dimensional (3D) simulations of network breakup. Our results for the late-time growth exponent and dynamical scaling of the structure factor s strongly indicate that the late-time growth kinetics of quenched polymer solutions belong to the same universality class of small molecular mixtures . (C) 1999 American Institute of Physics. [S0021-9606(99)50448-0].