CONFORMATION OF A(2)B AND A(3)B MIKTOARM STAR COPOLYMERS IN DILUTE-SOLUTIONS

The dimensionless ratio sigma(G), expressing quantitatively the effect s of heterointeractions between unlike units on the conformational pro perties of copolymers, has been determined experimentally by intrinsic viscosity analysis for the A(2)B and A(3)B miktoarm stars in various solvent conditions. In the case of symmetric samples (where the length s of A and B arms are the same) in a common good solvent, the values o f the required Flory parameter Phi for homopolymer stars with three an d four arms were used. For the other cases and solvent. conditions, Ph i was determined by extended Monte Carlo calculations which provide a lower bound of this quantity. The experimental values of sigma(G) are compared with the results obtained by Monte Carlo simulations and rece nt renormalization group predictions.