CONFORMER POPULATIONS AND THE EXCLUDED-VOLUME EFFECT IN LATTICE SIMULATIONS OF FLEXIBLE CHAINS IN SOLUTIONS

Monte-Carlo simulations on a tetrahedral lattice have been used to investigate whether a change in solvent quality induces gauche-trans conformational isomerization in the chain backbone. The populations of gauche states x(g) and of the all-trans sequences with length i bonds were calculated. The results show that the conformational equilibrium is affected by a solvent mainly in the short and flexible chains. The actual amount of solvent perturbation depends critically on the severity of intramolecular excluded volume interactions assumed in the lattice chain models. In discussion, a general neglect of this effect in the literature is pointed out which, in the light of the present study, seems to be warranted for long and semiflexible chains only.