SMALL-ANGLE NEUTRON-SCATTERING STUDY OF POLYMERIC MICELLAR STRUCTURES

Polymeric micellar structures formed by a PEO-PPO-PEO copolymer in o-x ylene in the presence of water were investigated by small-angle neutro n scattering. In order to reveal the detailed micellar structure, diff erent contrasts among the micellar core, the micellar shell, and the d ispersing medium (background) were constructed by selectively changing the protonated/deuterated combination of water and xylene. The micell ar structure could be well described by a core-shell structure with th e scattering behavior of the micellar shell being very similar to that of a star polymer. The solubilized water existed not only in the mice llar core but also in the micellar shell. The volume fraction of copol ymer segments in the micellar shell was rather low, being of the order of 0.2. There seemed to be no sharp interface between the micellar co n and the micellar shell.