BUTTERFLY-LIKE PATTERNS OF TRIBLOCK COPOLYMER GELS AS OBSERVED BY SMALL-ANGLE NEUTRON-SCATTERING

At high (150-1000%) stretching of a physical gel of a triblock copolym er a ''butterfly''-type scattering pattern is observed with a pronounc ed scattering-free strip perpendicular to the stretching direction. Th e phenomenon is attributed to the cluster character of the physical ne twork in the gel. Stretching brings endblock domains (junction points of the network) closer to each other in the direction perpendicular to the stretching and leads to formation of a layered structure. High co nnectivity of the network inside the clusters leads to saturation of t he deformation within the clusters as manifested by the scattering-fre e region in the SANS pattern. (C) 1996 John Wiley & Sons, Inc.