Monte Carlo Study of Dilute Solutions of Heteroarm Star Copolymers in Solvents Differing in Thermodynamic Quality

Lattice Monte Carlo simulations (an original modification of the Siepmann and Frenkel simulation variant) was used to study the conformational behavior of heteroarm star copolymers star-(polystyrene; polyisoprene), PS8PI8, in a common good solvent for both types of arms (tetrahydrofuran) and in selective θ-solvents for both types of arms (in cyclohexane, i.e., in θ-solvent for PS and in 1,4-dioxane, i.e. in θ-solvent for PI). Results of simulations were compared with experimental data published by Pispas et al. The coarse graining procedure was performed to match the experimental behavior of heteroarm stars in a good solvent. The computer simulations reproduce all decisive trends of the conformational behavior for both selective solvents. The quantitative agreement between experimental and simulated size characteristics is very good. Simulations yield very detailed information on the system at the molecular level and show that the incompatible arms significantly segregate in selective solvents.