Photoinitiated Polymerization-Induced Self-Assembly Based On Functional Monomer Copolymerization

Block copolymer assemblies have attracted increasing attention due to its great broad applications in fields including drug delivery,catalysis,coatings and nanoreactors.In recent years,a new method termed polymerization-induced self-assembly(PISA)has been developed to prepare block copolymer assemblies,which can produce block copolymer assemblies with controlled morphologies at high solids(solid content up to 50%).Although great progess has been made in PISA,the block copolymer assemblies usually lack functionalities for further crosslinking or functionalization.The most commonly used strategy for the functionalization of core-forming block is copolymerizing a small amount of functional monomers with core-forming monomers,allowing the incorporation of functional groups into the core-forming block.In this thesis,we focus on photoinitiated polymerization-induced self-assembly(photo-PISA)based on the copolymerization of functional monomers for the preparation of functional block copolymer nano assemblies.The main work is as follows:1.?-ketoester-functionalized block copolymer nanoparticles were prepared by in situ RAFT dispersion polymerization of 2-(acetoacetoxy)ethyl methacrylate(AEMA)in an alcohol/water mixture at room temperature using poly(2-hydroxypropyl methacrylate)(PHPMA)as a macro-RAFT agent and BAPO as a photoinitiator.By changing the monomer concentration and the degree of polymerization(DP),block copolymer assemblies with various morphologies were prepared and two morphological phase diagrams were constructed.A series of colloidal stable P(IBOMA-stat-AEMA)block copolymer nano assemblies were also prepared by introducing AEMA into photoinitiated RAFT dispersion polymerization of IBOMA at low reaction temperatures by changing reaction parameters.The results show that good RAFT control was maintained and the prepared polymers exhibited narrow molecular weight distributions(M_w/M_n<1.50).Cross-linking of block copolymer assemblies with ethylenediamine was developed to improve the structural stability.The obtained cross-linked assemblies were further used for in-situ loading of silver nanoparticles,exhibiting excellent catalytic performance.Finally,a series of lanthanide-containing block copolymer assemblies with fluorescence and magnetic properties were prepared by the interaction of lanthanide ions with?-ketoester group.2.A hydrophilic monomer,dimethylaminoethyl methacrylate(DMAEMA),was introduced into the aqueous RAFT dispersion polymerization of HPMA by using a trithiocarbonated terminated poly(glycerol methacrylate)(PGMA₄₃-CDPA)as the macro-RAFT agent to prepare block copolymer assemblies.The kinetic study showed that the phase separation occurred after4 min of 405 nm visible light and full monomer conversion was achieved within 10 min.Block copolymer assemblies with various morphologies were prepared by changing the DP of PHPMA and PDMAEMA.Transmission electron microscopy(TEM)showed that when the DP of PHPMA maintained at 200,the morphology of block copolymer assemblies transformed into higher-order morphologies as increasing the DP of PDMAEA.A zwtterionic monomer,[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide(DMAPS),was also used to copolymerize with HPMA to prepare block copolymer assemblies.The effect of hydrogen bonding on the morphology of block copolymer assemblies was also investigated.The effect of p H on the morphology of PGMA-b-P(HPMA-co-DMAEMA)assemblies was also investigated.3.In this chapter,PGMA₆₀-CDPA was also used as macro-RAFT and DMAEMA was used as the functional comonomer in photoinitiation RAFT aqueous dispersion polymerization of HPMA at room temperature to prepare block random copolymer nano-assemblies.The kinetic study indicated that a high rate of polymerization was achieved with over 98%monomer conversion being achieved within 10 min.The distribution of DMAEMA in the core-forming block was controlled by adding DMAEMA at different HPMA conversions.The effect of polymer sequence on CO₂responsive properties of block copolymer assemblies was studied.We found that the morphological transifiton of block copolymer assemblies after treating with CO₂,and different sequences exhibited different CO₂responsive properties.