BIREFRINGENCE AND DIFFRACTION OF LIGHT IN ORDERED BLOCK-COPOLYMER MATERIALS

The scattering of light from ordered block copolymer materials, consis ting of irregularly shaped birefringent grains with randomly oriented optic axes, is analyzed theoretically and experimentally. We show that independent estimates of the characteristic grain sizes can be obtain ed from the far-field angular spread of the diffracted light and from the total orthogonally polarized scattered power. Experimental measure ments on ordered polystyrene-polyisoprene diblock copolymer solutions in toluene support the predictions of the theory. Grain sizes estimate d from diffraction and total power measurements are in agreement. Such measurements should aid in the physical characterization of ordered b lock copolymer materials, as well as other random anisotropic media.