GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY 

on Tuesday, May 02, 2017

10:00 AM 

in MOSE 1201A

will be held the

DISSERTATION PROPOSAL DEFENSE 

for

Zewei Wang

"From Janus star-shaped-polymers to Janus bifunctional nanocrystals"

Committee Members:

Dr. Zhiqun Lin, Advisor, MSE

Dr. Vladimir Tsukruk, MSE

Dr. Dong Qin, MSE

Dr. Younan Xia, CHEM

Dr. Yulin Deng, CHBE

Abstract:

Janus structures named after the ancient twofaced Roman god Janus are composed of two hemi-structures (e.g., hemispheres) with different compositions and functionalities. The past decades have witnessed much research on Janus structures due to the intriguing properties and promising potential applications of these unusually shaped materials as sensors, imaging, nanomotors, drug delivery carriers, multifunctional surfactants, stabilizers, etc. According to different compositions, strictly biphasic Janus structures can be divided into three categories: soft (i.e., polymeric), hard (e.g., inorganic), and hybrid soft/hard. In addition, based on the architecture and dimensionality, they can also be classified into spherical Janus particles, dumbbell-like, rod-like, disc-like, and sheet-like (or ribbon-like). In this thesis, efforts are focused on crafting perfectly biphasic Janus nanoparticle consisting of two completely dissimilar materials. We aim to develop a general and robust synthetic strategy for Janus nanoparticle with controlled size and shape. To this end, amphiphilic Janus star-like block copolymer is first synthesized via the combination of reversible addition-fragmentation chain transfer polymerization (RAFT) and atom transfer radical polymerization (ATRP). These Janus amphiphilic star-like block copolymers are then capitalized on as nanoreactors for in-situ synthesis of Janus nanoparticles with two hemispheres consisting of two dissimilar inorganic functional materials (e.g., plasmonic/magnetic, plasmonic/semiconducting, amorphous/crystalline, tetragonal/cubic, etc.). The size of each hemisphere can be precisely tuned by controlling the length of corresponding block in Janus amphiphilic star-like block copolymers. The physical properties of these Janus nanoparticles will be studied and their self-assembly behaviors will be investigated. The applications of these Janus nanoparticles in energy related fields will also be explored.