In-situ Synthesis Of Functional Multicompartment Block Copolymer Nanoparticles

The self-assembling block copolymer has been an important research topic in the field of polymer and nanotechnology, and of all the self-assemblies of block copolymers, multicompartment block copolymer nanoparticles(MCBNs) composed of a solvophilic corona and a solvophobic microphase-separated core have garnered great interest, since the microphase-separated core in MCBNs presents the opportunity to selectively entrap and release multiple hydrophobic ingredients with enhancement in functionality over simple corona-core structures containing a single hydrophobic environment. Self-assembly or micellization of amphiphilic block copolymer(s) in the block-selective solvent is a general method to prepare these MCBNs. However, this strategy suffers from two disadvantages:(1) the time consuming multiple steps and(2) block copolymer nanoparticles with very dilute polymer concentration(usually below 1 wt %) and poor stability. Dispersion polymerization is a convenient method to synthesize polymeric nanoparticles. By employing the reversible addition fragmentation chain transfer(RAFT) technology in the dispersion polymerization, block copolymer nano-objects with high polymer concentration have been successfully prepared. Inspired by this strategy, in this study, three strageties including high molecular weight brush macro-RAFT agent, two linear macro-RAFT agents and seeded(co-)mediated dispersion RAFT polymerization are proposed. And well-difined MCBNs of(A-g-B)-b-C brush block terpolymer, AB/A?B diblock copolymers, and linear ABC triblock terpolymer are prepared. Therefore, the content of this dissertation is described in three aspects: 1. Multicompartment nanoparticles of(A-g-B)-b-C block te rpolyme r: synthesis and application as scaffold for efficient Au nanocatalystIn this section, MCBNs constructed with the brush block terpolymer of poly[p-chloromethylstyrene-g-poly(4-vinylpyridine)]-b-polystyrene [P(CMS-gP4VP)-b-PS] are prepared through dispersion polymerization of styrene in the methanol/water mixture mediated by the brush macro-RAFT agent of P(CMS-gP4VP)-TTC. During the dispersion RAFT polymerization, the molecular weight of the brush P(CMS-g-P4VP)-b-PS block terpolymer linearly increases with the monomer conversion. The size of the MC BNs of P(CMS-g-P4VP)-b-PS increases with the DP of the PS block, whereas the size of the P(CMS-g-P4VP) sub-domains is matched approximately with that of one fully shrunk P(CMS-g-P4VP) chain. Besides, Au nanoparticles are immobilized on the bulgy P(CMS-g-P4VP) sub-domains on MCBNs and show high catalytic efficiency in the aerobic alcohol oxidation. 2. Temperature- and pH-sensitive AB/A?B multicompartment nanoparticles prepared through two macro-RAFT agents co-mediated dis persion polymerizationIn this section, an efficient strategy to prepare well-defined temperature- and pH-sensitive MCBNs constructed with two diblock copolymers of poly(4-vinylpyridine)-b-polystyrene(P4VP-b-PS) and poly(N-isopropylacrylamide)-b-polystyrene(PNIPAM-b-PS) through the two macro-RAFT agents co- mediated dispersion polymerization is proposed. These MCBNs contain a solvophobic PS core, discrete P4 VP nodules on the PS core and a solvophilic PNIPAM corona. Then the influence of the ratio of two macro-RAFT agents of PNIPAM and P4 VP and PS chains length on the morphology of the MCBNs was investigated. It is found that, the higher percent of the P4 VP macro-RAFT agent and the shorter PS block, the larger size of the P4 VP nodules on MCBNs. Furthermore, through the phase transition of the temperature-responsive PNIPAM block and the pH-responsive P4 VP block, the morphology of MC BNs can be changed. 3. Redox-responsive multicompartment vesicles of ferrocene-containing ABC triblock terpolymer exhibiting on-off switchable poresIn this section, a new kind of MC BNs of the poly[2-(dimethylamino) ethyl methacrylate]-b-poly(benzyl methacrylate)-b-poly(4- vinylbenzyl ferrocenecarboxylate)(PDMAEMA-b-PBzMA-b-PVFC) triblock terpolymer, named propous multicompartment vesicles(PMVs), are prepared by seeded RAFT dispersion polymerization. These PMVs have porous and phase-segregated membrane constructed with the incompatible PVFC and PBzMA blocks, and the membrane structure is dependent on the DP of the PVFC block. Through oxidation and reduction of the ferrocene-containing redox-responsive PVFC block, the multicompartment vesicles exhibit reversibly on-off switchable pores in the membrane.As a whole, kinds of MCBNs such as the(A-g-B)-b-C multicompartment block terpolymer nanoparticles, the AB/A?B multicompartment block copolymer nanoparticles and the multicompartment ABC triblock terpolymer vesicles have been synthesized and their app lication in catalysis and smart materials have been explored. In addition, several strategies for in-situ synthesis of MCBNs, including high molecular weight brush macro-RAFT agent, two linear macro-RAFT agents and seeded(co-)mediated dispersion RAFT polymerization have been proposed.