Fabrication Of Supramolecular Assemblies And Functional Materials Based On Responsive Polymers

The supramolecular self-assembly of polymeric building blocks via noncovalent interactions has exhibited important roles in developing novel biomaterials, smart devices, information science, and nanotechnology, which renders this interdisciplinary research subject as one of the key scientific issues in the 21st century. This dissertation mainly focuses on the controlled synthesis, fabrication, and structural tuning of stimuli-responsive supramolecular polymeric assemblies, inorganic/polymer hybrid nanoparticles. A series of amphiphilic and double hydrophilic miktoarm star terpolymers were synthesized. In aqueous solution, chain architectural effects on thier self-assembling properties under varying solution conditions were investigated. Moreover, inorganic/polymer hybrid nanoparticles were investigated. This dissertation can be further categorized into seven main parts as described below:1. Amphiphilic ABC miktoarm star terpolymer consisting of polystyrene, poly(ε-caprolactone), and poly(N-isopropylacrylamide) arms, PS(-b-PNIPAM)-b-PCL, was synthesized via a combination. of atom transfer radical polymerization (ATRP), ring-opening polymerization (ROP), and consecutive click reactions. In aqueous solution, the obtained amphiphilic miktoarm star terpolymer self-assembles into micelles possessing mixed PS/PCL cores and thermo-responsive coronas. We also report on the one-pot synthesis of well-defined ABC miktoarm star terpolymers consisting of poly(2-(dimethylamino)ethyl methacrylate), poly(ε-caprolactone), and polystyrene or poly(ethylene oxide) arms, PS(-b-PCL)-b-PDMA and PEO(-b-PCL)-b-PDMA, taking advantage of the compatibility and mutual tolerability of reaction conditions (catalysts and monomers) employed for ATRP, ROP, and click reactions. We report the first example of synthesis and "schizophrenic" micellization behavior of multi-responsive double hydrophilic ABC miktoarm star terpolymer. A well-defined miktoarm star terpolymer consisting of poly(ethylene glycol), poly(2-(diethylamino)ethyl methacrylate), and poly(N-isopropylacryl-amide) arms, PEG(-b-PDEA)-b-PNIPAM, was synthesized via the combination of ATRP and click reaction. This novel type of miktoarm star terpolymer molecularly dissolves in aqueous solution at acidic pH and room temperature, but supramolecularly self-assembles into PDEA-core micelles at alkaline pH and room temperature, and PNIPAM-core micelles at acidic pH and elevated temperatures. Most importantly, both types of micellar aggregates possess well-solvated hybrid coronas. A well-defined ABC miktoarm star terpolymer consisting of biocompatible poly(ethylene oxide), poly(e-benzyloxycarbonyl-L-lysine), and poly(e-caprolactone) arms, PEO(-b-PZLL)-b-PCL, was synthesized via the combination of consecutive click reactions and ROP. In aqueous solution, the obtained amphiphilic miktoarm star terpolymer self-assembles into micelles possessing PCL cores and mixed PEO/PLL coronas.2. Poly(N-isopropylacrylamide)-b-poly(γ-methacryloxypropyltrimethoxysilane) (PNIPAM-b-PMPS) was prepared by successive reversible addition-fragmentation transfer (RAFT) polymerizations. Thermo-responsive polymer-encapsulated silica hybrid nanoparticles were fabricated via self-assembling of block copolymer in aqueous solution into micelles and subsequent sol-gel process inside the micellar core. And we also report the facile preparation of hybrid nanoparticles starting from a amphiphilic block copolymer, poly(2-(dimethylamino)ethylmethacrylate)-b-poly(γ-methacryloxypropyltrimethoxysilane)(PDMA-b-PMPS), block copoly-mer. Micellization of the obtained amphiphilic diblock polymer in aqueous solution leads to the formation of nanoparticles consisting of PMPS cores and PDMA shells. The PDMA block can spontaneously catalyze the sol-gel reactions of trimethoxysilyl groups within PMPS cores, leading to the formation of hybrid nanoparticles coated with PDMA brushes. PDMA brushes exhibit pH and thermo-responsiveness, the swelling/collapse of them can be finely tuned with solution pH and temperatures. The thermo-responsive dopamine-terminated PNIPAM was synthesized by ATRP, the thermo-responsive Fe3O4/polymer hybrid nanoparticles was obtained through the ligand exchange reaction with dopamine-terminated PNIPAM and Fe3O4 nanoparticles. An amphiphilic ABC miktoarm star terpolymer consisting of poly(ethylene oxide), poly(dopamine methacrylamide) and polystyrene, PEO(-b-PDOPA)-b-PS, was synthesized via a combination of ATRP and click reactions. The amphiphilic Fe3O4 polymer hybrid nanoparticles was obtained through the ligand exchange reaction with PEO(-b-PDOPA)-b-PS and Fe3O4 nanoparticles. In aqueous solution, the amphiphilic hybrid nanoparticles can self-assembles into hybrid vesicles.