Date of Award

Summer 2022

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

First Advisor

Brian Benicewicz

Abstract

Surface functionalization of nanoparticles has proven to be a powerful and versatile strategy in the development of various materials with advanced properties. Polymer brush composition can range from complex copolymers to more simplistic polyolefin, and by functionalizing nanoparticle surfaces, mobility of distinct particles can then be tuned and, therefore, control over dispersion in a polymer matrix can be achieved. Presented in this dissertation are new synthetic strategies for the preparation of polymer nanocomposites.

The first chapter covers a novel synthetic strategy for ethylene/propylene-like copolymers grafted to silica nanoparticles. This approach utilizes Reversible Addition-Fragmentation Chain Transfer (RAFT) polymerization to promote living polymerization characteristics with the monomers: isoprene and 2,3-dimethyl-1,3- butadiene (DMB) to obtain an unsaturated precursor which can then be hydrogenated giving the desired ethylene/propylene copolymer nanocomposites. Having the unsaturated precursor is advantageous as it offers facile determination of monomer composition and higher molecular weights can be achieved.

The next chapter discusses a new approach toward polyethylene grafted silica nanoparticles via RAFT polymerization with use of the monomer, 1,3-butadiene followed by mild hydrogenation. Compared to using Ring-opening Metathesis Polymerization (ROMP) approach, this strategy offers an accurate determination of graft density prior to polymerization through monitoring the absorbance of the RAFT agent.

The final chapter is an extension of the previous work in synthesis of ethylene/propylene copolymer nanocomposites. With the incorporation of 1,3- butadiene in the copolymerization, high ethylene content can be achieved. Additionally, previous work has shown sterically hindered butadiene-based monomers, i.e. DMB and isoprene, are less favorable toward complete hydrogenation leaving reactive double bonds in the polymers. Through a thermally-activated thiol-ene click reaction, these double bonds can be consumed and converted into thiol ethers.

The dissertation will conclude with a summary including key points of significant results and main takeaways. Potential direction for future work will also be discussed.

Included in

Chemistry Commons

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