Surface modification of nanoparticles by polymer grafting
Abstract
One of the key issues associated with the utilization of nanoparticles is to control their interfacial properties. A common approach to this is to modify the surfaces of nanoparticles with end-grafted polymers. This thesis concerns fundamental issues arising in the polymeric surface modification of several widely used nanoparticles: gold nanorods (GNRs), iron/gold (alloy) nanospheres (IGNSs), and carbon nanotubes (CNTs). GNRs and IGNSs have the potential to be used as optical/MRI imaging and hyperthermia agents for cancer theranosis. Clinical applications of as-synthesized GNRs or IGNSs are currently limited by their cytotoxicity and insufficient colloidal stability. With an aim to address these problems, we developed a self-assembly processing technique for encapsulation of GNRs or IGNSs in poly(ethylene oxide)-poly(n-butyl acrylate) (PEO-PnBA) block copolymer (BCP) micelles. This technique uses simple steps of solvent exchange processes designed based on the known principles of block copolymer self-assembly. The resultant BCP-encapsulated GNRs/IGNSs were found to be stable against aggregation under physiological salt conditions for indefinite periods of time, which has rarely previously been achieved with other means of encapsulation. Nanocomposites between CNTs and polymers have attracted great interest of researchers in the hope that such formulation improves the properties of the polymeric materials for various applications. Unfortunately, CNT particles are in general very difficult to disperse in polymeric media. To obtain better dispersed CNT particles, an in situ polymerization technique using CNTs surface-functionalized with reactive chemical groups has been proposed. In prior studies of this approach, the role that the reaction stoichiometry plays in determining the physical properties (such as the glass transition property) of the in situ-polymerized nanocomposite product has not been examined. A chapter is also devoted to address this issue.
Degree
Ph.D.
Advisors
Won, Purdue University.
Subject Area
Polymer chemistry|Chemical engineering|Materials science
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