Preparation And Self-assembly Of Block Copolymer/Prussian Blue Nano-particles Hybrid

In this paper, a new type of block copolymers, polystyrene-b-poly[(N-isopropyl acrylamide)-co-(vinyl benzyl chloride)] (PS-b-P(NIPAM-co-VBC)) was prepared via reversible addition fragmentation transfer polymerization (RAFT). First, the macro-chain transfer agent (PS-Macro-RAFT Agent) was prepared, then random copolymerization of NIPAM and VBC was initiated under the control of PS-Macro-RAFT Agent. Three block copolymers with different compositions and with narrow molecular weight distributions were obtained by changing the molar ratio among initiator, chain transfer agent and monomer. The block copolymers were characterized by GPC and 1H-NMR. The Prussian Blue precursor, Fe-DMAP, was successfully attached to the block copolymer's side chain through a quaternization process between functional monomer of VBC and Fe-DMAP, then the Fe(Ⅱ)-coordinated block copolymers, PS-b-P[NIPAM-co-(VBC-Fe-DMAP)], were obtained. The products were characterized by 1H-NMR and FT-IR. Besides, the phase transition behavior of the Fe(Ⅱ)-coordinated block copolymers was investigated by small angle X-ray scattering (SAXS).The self-assembly behavior of the Fe (Ⅱ)-coordinated block copolymers in aqueous phase and in organic solvent (DMF/MeOH) was also studied. It is found that the Fe(Ⅱ)-coordinated block copolymer is not stable in aqueous phase, and the morphology of the self-assembled micelles is not regular and uniform. On contrast, the dissociation reaction after the quaternization process can be efficiently supressed in organic solvent. Moreover, TEM observations reveal that the micellar morphology becomes more uniform due to the change of the solubility.Prussian Blue (PB) nano-particles were synthesized using the Fe(Ⅱ)-coordinated block copolymer as the template. Different methods were exploredfor the preparation of PB nano-particles. It is found that the Fe(Ⅱ)-coordinated block copolymers can form Janus micelles.Finally, the block copolymer PMMA-b-PHEMA was synthesized through ATRP, and its phase transition behaviour was studied by SAXS.