Kinetics at the collapse transition of homopolymers and random copolymers

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Abstract
We describe the results of Monte Carlo simulations for kinetics at the collapse transition of a homopolymer in a lattice model. We find the kinetic laws corresponding to the three kinetic stages of the process: R2g(t)=R2g(0)−At7/11 at the early stage corresponding to formation and growth of locally collapsed clusters, the coarsening stage is characterized by growth of clusters according to the law S∝t1/2, where S is the average number of Kuhn units per cluster, and the final relaxation stage is described by the law R2g(t)=R2g(∞)+A1(1)e−t/τ1(1) with τ1(1)∝N2. We also present preliminary results on the equilibrium properties and ‘‘collapse’’ transition of a random copolymer. The transition curve is determined as a function of hydrophobic bead concentration na. We discuss the different collapsed copolymer states as a function of the composition. At low hydrophilicity we believe the critical value of the interaction parameter is governed by the law χc(na)∝na−2/3. In the kinetics we see unusual phenomena such as the appearance of a metastable long-lived states with few clusters and nontrivial loop structure.