3D cellular automata of polymer structural response to solvent quality

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.