Critical exponents and universality for the isotropic-nematic phase transition in a system of self-assembled rigid rods on a lattice

Monte Carlo simulations have been carried out for a system of monomers on square lattices that, by decreasing temperature or increasing density, polymerize reversibly into chains with two allowed directions and, at the same time, undergo a continuous isotropic-nematic (I-N) transition. The results show that the self-assembly process affects the nature of the transition. Thus, the determination of the critical exponents indicates that the universality class of the I-N transition changes from two-dimensional Ising-type for monodisperse rods without self-assembly to q=1 Potts-type for self-assembled rods.