PHASE SEGREGATION DYNAMICS OF A CHEMICALLY REACTIVE BINARY MIXTURE

We investigate a model system of a chemically reactive binary mixture, where the simple reaction A reversible arrow B between the two consti tuents of the mixture occurs simultaneously with spinodal decompositio n. The competition between the thermodynamic short-range attractive an d the reactive long-range repulsive interactions leads to the formatio n of steady-state patterns. In the case of equal forward and backward reaction rates the steady-state average domain width, R(infinity), sca les with the reaction rate, Gamma, as R(infinity) similar to(1/Gamma)( s), where the exponent a equals approximately 1/3 for low rates and eq uals exactly 1/4 for high rates. These exponent values and the variati on of the maximum amplitude of the order parameter with the reaction r ate can be derived by minimizing the free energy in a square wave and a single mode approximation, respectively. The phases segregation dyna mics is simulated numerically using the appropriate Langevin equation.