Particle scattering form factors of chemical and conformational triblock copolymers

Partially substituted derivatives of cellulose display unusual behavior. Ag gregates are found which resemble star-branched macromolecules. The dimensi ons of these aggregates are large and indicate either an uncommon chain sti ffness of the arms, or a structure that consists of two star-branched coron as which are connected over a rigid stem composed of f-laterally aggregated cellulose chains. This structure may be considered as the smallest object in the fringed micellar crystal structure of native cellulose and is given the name fringed micelle. Ln the present paper the angular dependence of th e scattering intensity in visible light (LS) and small angle neutron scatte ring (SANS) of such conformational tri-block copolymers is derived. The the ory is based on the mean field approach. Closed expressions are obtained by application of Gordon's cascade theory. The theory can describe the scatte ring curves in the whole q = (4 pi/lambda)sin(theta/2) range of LS and SANS . The derived solutions have to be considered as a first approximation sinc e the effect of excluded volume has not been taken into account. Attempts a re in progress to find a suitable approximation for this problem. (C) 2000 Elsevier Science Ltd. All rights reserved.