THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING  

GEORGIA INSTITUTE OF TECHNOLOGY  

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Tuesday, October 11, 2022  

11:00 AM

in MoSE 1226

will be held the  

DISSERTATION PROPOSAL DEFENSE

for  

Woosung Choi

"Unimolecular Polymer Micelles with Different Architectures and Functionalities for Rendering Hairy Nanocrystals with Tailorable Dimensions, Surface Chemistry, and Optical and Catalytic Properties"

Committee Members:  

Prof. Zhiqun Lin, Advisor, MSE  

Prof. Vladimir Tsukruk, Advisor, MSE  

Prof. Seung Soon Jang, MSE  

Prof. Zhitao Kang, GTRI/MSE  

Prof. Will Gutekunst, CHEM  

Abstract:

The ability to synthesize colloidal nanocrystals with controlled size, shape, composition, and surface chemistry is key to interrogating their dimension-dependent physical properties and thus applications in nanobiotechology. In this context, my research expands unimolecular polymer micelle nanoreactor platform developed in our group by introducing degradability and chirality to unimolecular micelles to synthesize an array of uniform inorganic nanomaterials of interest with controlled dimensions (both length and diameter) and surface chemistry (hydrophobic, degradable or chiral). The as-synthesized nanomaterials will be studied for their electrocatalytic and plasmonic properties. Specifically, nonlinear block copolymers are synthesized from renewable sources (i.e., cyclodextrin (CD) and cellulose). The molecular weight (MW) of each block is precisely controlled by atom transfer radical polymerization (ATRP) or reversible addition fragmentation chain transfer (RAFT) polymerization, rendering polymer nanoreactors that direct the formation of a library of inorganic nanocrystals (i.e., star-like nanoreactor for nanoparticle growth and bottlebrush-like nanoreactor for nanorod growth). The inner block from the CD macroinitiator is hydrophilic poly (4-vinylpyridine) (P4VP) or hydrophobic poly (tert-butyl acrylate) (PtBA; converted into hydrophilic polyacrylic acid (PAA) via acidic treatment later). The outer block is hydrophobic polystyrene (PS), chiral polylactic acid (PLL(D)A), or degradable poly(n-butyl acrylate-ran-cyclic sulfone). The hydrophilic inner P4VP and PAA blocks have the ability to coordinate with metal moieties of inorganic precursors, thereby confining the nucleation and growth of inorganic nanocrystals within them.  

After the syntheses of star-like PAA-b-PS, bottlebrush-like PAA-b-PS, star-like P4VP-b-PLL(D)A, and star-like PAA-b-PnBA-ran-cyclic sulfone, as assortment of inorganic nanocrystals (0D and 1D) will be grown to scrutinize their optical and catalytic properties along with degradability. For instance, PS-ligated Pt nanoparticles, 1D nanorods (1D nanoclusters as well) will be synthesized from star-like and bottlebrush-like PAA-b-PS, respectively, to examine the effect of the morphology, surface area, and crystal surfaces on electrocatalysis. Moreover, star-like P4VP-b-PLL(D)A with different molecular weight ratio of the two blocks will be employed to explore their self-assembly, followed by investigation into chiral plasmonics after template-grown into PLL(D)A-capped Au nanoparticles. Furthermore, ideal random copolymerization will be realized in star-like PAA-b-PnBA-ran-cyclic sulfone for efficient degradation and catalytic property of the resulting PnBA-ran-cyclic sulfone-capped Pt nanoparticles before and after the degradation PnBA-ran-cyclic sulfone will be assessed.