Morphology and Thermoresponsive Behavior of Hybrid Micelles of Polystyrene-b-Poly((N-isopropyl acrylamide)-co-(4-vinylbenzyl chloride)) with Prussian Blue

The hybrid micelles of polystyrene-b-poly（（N-isopropyl acrylamide）-co-（4-vinylbenzyl chloride）） block copolymer（PS-b-P（NIPAM-co-VBC）） with Prussian blue（PB） in the corona were prepared by reaction of pentacyano（4-（dimethylamino）-pyridine）ferrate（Fe-DMAP）-attached PS-b-P（NIPAM-co-VBC） with Fe Cl3. The formation of the PB framework inside the micelles was verified by UV-Vis, FTIR and TGA. The morphology of the hybrid micelles was studied by TEM and compared with that of the neat and Fe-DMAP-attached PS-b-P（NIPAM-co-VBC）. It is found that attachment of Fe-DMAP may change the short rod-like micelles of the neat PS-b-P（NIPAM-co-VBC） into spherical ones and lead to a smaller micelle size. The morphology of the hybrid micelles may be altered or remain unchanged after formation of the PB framework, depending on the chain structure of PS-b-P（NIPAM-co-VBC） and starting concentration. The thermoresponsive behavior of different micelles was studied using DLS. It is observed that attachment of Fe-DMAP can improve the hydrophilicity of the P（NIPAM-co-VBC） block, leading to weaker hysteresis of the micelle size during the heating and cooling cycle. However, the crosslinked PB framework in the micellar corona may result in a more evident hysteresis phenomenon and blur the two-stepwise change of the micellar size with temperature.