Monte Carlo simulation of tetrahedral chains, 7 the shape of linear and star‐branched polymers near to theta‐conditions

Abstract

AbstractBy use of the pivot algorithm, star‐branched chains with F = 4, 8 and 12 arms of length n and linear chains (F = 2) are generated on a tetrahedral lattice (120 ≤ nF ≤ 3 840). By taking into account nearest neighbour interactions (each contact contributes an energy ϕ kT to the total energy of the configuration) a variation of the thermodynamic quality of the solvent is simulated by a variation of the energy parameter ϕ near the value of ϕθ = ‐0,475, characteristic of theta‐conditions. For theta‐conditions various quantities characteristic of the instantaneous shape of polymers exhibit similar values as found for nonreversal random walks; furthermore, while linear theta‐chains are slightly less asymmetric than athermal ones, the opposite behaviour is found for star‐branched polymers. Clearly, for all thermodynamic conditions the asymmetry of configurations decreases with increasing number of arms but remains appreciable even for F = 12.