CORRELATION HOLE EFFECT IN COMB-LIKE COPOLYMER SYSTEMS OBTAINED BY HYDROGEN-BONDING BETWEEN HOMOPOLYMERS AND END-FUNCTIONALIZED OLIGOMERS

This paper addresses concentration fluctuations in comblike copolymer systems obtained by hydrogen bonding between polymers and end-function alized oligomers. Monodisperse block copolymer systems in the homogene ous melt exhibit small-angle X-ray scattering peaks at finite nonzero angle due to characteristic correlation hole concentration fluctuation s. In comblike copolymer systems obtained by hydrogen bonding, the dom inant fluctuations have been found by us to vary experimentally betwee n conventional long wavelength fluctuations (for weak hydrogen bonding ) and finite wavelength fluctuations (strong hydrogen bonding). Monte Carlo computer simulations show that both regimes occur in one and the same system depending on the temperature. The transition between both regimes is directly related to the fraction of free oligomers, which depends on the temperature and the interactions. The structure factors are analyzed in terms of the random phase approximation applied to a mixture of free oligomers and comb copolymers, using a uniform distrib ution of teeth along the polymer chains and a binomial distribution in the number of polymers with a given number of teeth, confirmed numeri cally, as input. The agreement is excellent at both high and low tempe ratures.