Alternating Multiblock Copolymers Exhibiting Protein-Like Transitions in Selective Solvents: A Monte Carlo Study
S. Wołoszczuk1 , M. Banaszak1 , P. Knychała1 , K. Lewandowski1 , M. Radosz2
1 Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614, Poznan, Poland
2 Department of Chemical and Petroleum Engineering University of Wyoming, Laramie, WY 82071-3295, USA
Journal of Non-Crystalline Solids, 354 (2008) 4138–4142 (2008)
We present a lattice Monte Carlo study of a series of block copolymer chains in selective solvents of varying quality, first using a diblock chain of the length of N = 32 with a 16–16 microarchitecture, and then – two multiblock chains of N = 64 and N = 128, with (8—8)4 and (16—16)4 microarchitectures, respectively. We report a variety of thermodynamic and structural properties, such as energy, specific heat, end-to-end distance and radius of gyration both for the whole chain and for individual blocks. The simulations have demonstrated that a multiblock copolymer in a selective solvent exhibits protein-like behavior undergoing a two-step transition, first from a swollen state to a secondary ‘pearl-necklace’ state and then to a tertiary super-globular state as the solvent quality decreases, i.e. upon cooling. We have found that mean-squared end-to-end distances of multiblock chains decrease as the temperature is reduced, as expected.