Molecular orientation in polymers from near-field optical polarization measurements

Abstract

A combined noncontact shear force and scanning near-field optical microscope has been used to study the structure of a spherulitic polyhydroxybutyrate specimen. Using polarized light, the birefringence structure of the spherulite revealed a concentric ring structure with submicron resolution. Optical images could be correlated with the topographic images, recorded simultaneously, of the same area. This demonstrated directly the correlation between the twisting structure of the ribbonlike polymer crystallites and the birefringent concentric ring structure, and demonstrates the capability of scanning near-field optical microscopy for studying molecular orientation as a function of topographic structure.