In this work, a cellular automaton in three dimensions (3DCA) is presented for describing the structural response of polymer systems to solvent quality. Polymer segments occupy a cubic lattice and evolve through local exchange moves between solvent and polymer, with fixed chain connectivity, excluded volume, rejection of bond crossings, interactions between nearest neighbours and an acceptance criterion of the Metropolis type. The solvent quality is controlled by the interaction energy between solvent and polymer, while the cohesion among polymer segments is described by a separate contact energy.
The model reproduces the distinct regimes of poor, θ and good solvents, including the collapse of chains, intermediate coil conformations, swelling and aggregation. The scaling of the radius of gyration identifies the θ condition through a Flory exponent close to 0.50 and provides a basis for relating the interaction energies on the lattice to the Flory-Huggins parameter.
Simulations with several chains further show that the topology of the chains strongly affects the structural evolution. Finite chains undergo pronounced restructuring associated with their free ends, whereas periodically self-connected chains preserve fibrillar morphologies that span the whole system more effectively.
The model therefore provides a minimal and transparent framework for linking local interaction rules to the mesoscale structure of polymers in solvents of different quality. The simulation code, written in Python, and the data are openly available together with the workflow that leads from the simulation to the published figures, which supports reproducibility and further development.
This study was carried out at the Institute of Thermal Separation Processes at Hamburg University of Technology within the Collaborative Research Centre CRC 1615 (SMART Reactors).
Vasilii Korotenko, Irina Smirnova, Pavel Gurikov (2026). 3D Cellular Automata of Polymer Structural Response to Solvent Quality. Macromolecular Theory and Simulations 35 (6), e70060.
