Small-angle Neutron Scattering of Amphiphilic Block Copolymers in Aqueous Solutions

摘要

The small angle neutron scattering has been employed to investigate the structural transitions of thermosensitive block copolymer consisting of poly(2-ethoxyethyl vinyl ether-b-2-hydroxyethyl vinyl ether) (EOVE-HOVE) in aqueous solutions. The EOVE-HOVE undergoes micellization with EOVE core of ca. 20 nm in radius and HOVE corona around 17 - 21°C, depending on the polymer concentration. At higher temperatures, a second transition takes place from micelle to macro-lattice structures with body-centered cubic (bcc) symmetry. The radii of the spheres were quantitatively analyzed by curve fitting with a theoretical scattering function in which the various types of smearing effects, such as polydispersity of spheres, incident beam smearing, and a smearing due to a finite wavelength distribution of the incident neutron beam.