Interpretation of small angle neutron scattering by copolymer solutions as a function of concentration

2014 Using a generalization of the Random Phase Approximation (RPA) for a three-component system, the intensity scattered by a two-block copolymer has been calculated in the two special cases : a) the coherent scattering length of the solvent is identical to the coherent scattering length of one of the blocks, b) the difference between the average scattering length of the whole molecule and the solvent is zero. Expressions are explicitly given and discussed as a function of the concentration and the momentum transfert q assuming the solvent to be good for both sequences. Experimental results obtained by small angle neutron scattering on a two block copolymer PSH-PSD (hydrogenated and deuterated Polystyrene) in a mixture of hydrogenated and deuterated benzene show a good agreement between the theory and the experiments. J. Phys. France 49 (1988) 1963-1968 NOVEMBRE 1988, 1 Classification Physics Abstracts 61.12 78.35