Date of Award

12-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Materials Science and Engineering

Committee Member

Dr. Marek W. Urban, Committee Chair

Committee Member

Dr. Igor Luzinov

Committee Member

Dr. Olin Thompson Mefford

Committee Member

Dr. Mark Roberts

Abstract

This dissertation focuses on the design, synthesis and characterization of stimuli-responsive anisotropic nanoparticles with various morphologies. Size- and shape-tunable Janus nanoparticles consisting of poly(methyl methacrylate/n-butyl acrylate) (p(MMA/nBA)), poly(pentafluorostyrene/nBA) (p(PFS/nBA) and poly(2-(N,N′-dimethylamino) ethyl methacrylate/nBA) (p(DMAEMA/nBA)) phases were synthesized via consecutive seeded emulsion polymerization. These Janus nanoparticles are capable of changing size and morphology in response of temperature and/or pH changes, which may have potential applications as solid surfactants. Gibbous and inverse-gibbous nanoparticles were synthesized viacopolymerization of fluorinated monomers in the presence of pMMA or polystyrene (pSt) seed particles. The morphology of the gibbous nanoparticles can be controlled by polymerization conditions. Incorporation and copolymerization of methacrylic acid (pMAA) components results in pH-responsive gibbous nanoparticles with numerous size-tunable bulges. In addition, the gibbous and inverse-gibbous nanoparticles can be controlled to self-assemble in solutions but upon evaporation of solvents form two- and three-dimensional assemblies stabilized by electrostatic interactions and shape-matching topographies. Taking advantage of the heterogeneous nature of emulsion polymerization, surfactant free heterogeneous radical polymerization (SFHRP) was developed to synthesize ultra-high molecular weight amphiphilic block copolymers. This is one-step process of preparing block copolymer morphologies. The amphiphilic block copolymers can form thermochromic inverse micelles in organic solvents, capable of selectively scattering light as a function of temperature. The approach was also utilized to synthesize polymer nanowires via in-situ self-assembly of amphiphilic block copolymers. This kinetically controlled directional growth may lead to many industrial applications, including synthesis of other block copolymers, polymeric nanowire latexes and other morphologies.

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