Abstract
A three-dimensional cellular automaton (3DCA) model is presented for describing the structural response of polymer systems to solvent quality. Polymer segments occupy a cubic lattice and evolve through local solvent-polymer exchange moves with fixed chain connectivity, excluded volume, bond-crossing rejection, nearest-neighbor interactions, and Metropolis-type acceptance. Solvent quality is controlled by the solvent-polymer interaction energy, while polymer-polymer cohesion is described by a separate contact energy. The model reproduces distinct poor-, θ-, and good-solvent regimes, including chain collapse, intermediate coil conformations, swelling, and aggregation. Radius-of-gyration scaling identifies the θ condition through a Flory exponent close to 0.50 and provides a basis for relating the lattice interaction energies to the Flory-Huggins parameter. Multichain simulations further show that chain topology strongly affects structural evolution: finite chains undergo pronounced restructuring associated with free chain ends, whereas periodically self-connected chains preserve fibrillar and system-spanning morphologies more effectively. The model therefore provides a minimal and transparent framework for linking local interaction rules to solvent-dependent mesoscale polymer structure, supported by an openly available simulation-to-figure workflow.
