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Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemistry

Year Degree Awarded

2018

Month Degree Awarded

February

First Advisor

Sankaran Thayumanavan

Subject Categories

Nanomedicine | Nanoscience and Nanotechnology | Polymer and Organic Materials

Abstract

Engineering of supramolecular assemblies at molecular level renders functional nanomaterials that present explicit response to certain environmental changes. Systematic structure-property correlation studies will unravel the fundamental design constraints of these functional nanomaterials that fulfill the emergent need. This dissertation will primarily focus on understanding the role of rigidity and flexibility of functional groups within amphiphilic assemblies and employing this basic concept in drug delivery and diagnostics applications.

Supramolecular assemblies formed by amphiphilic dendrimers and polymers are preferred for this study as they exhibit high thermodynamic stability and structural flexibility. The role of aromatic interaction on the unimer-aggregate dynamic equilibrium was systematically studied using facially amphiphilic dendrimers. We show that the aromatic interaction contributes to the stability of guest encapsulation by generating more rigid assemblies via pi-pi stacking. Fundamental principles obtained from these rigid assemblies were translated into synthetically more feasible polymeric designs and exploited to develop stable nanocarriers with enhanced encapsulation efficiency for drug delivery applications.

On contrary to interior rigidity, an effect of the interior flexibility or mobility of embedded hydrophobic functional groups were explored. We developed a new strategy to generate interior flexibility in polymeric nanogels by using cleavable functional groups and demonstrated the enhancement in segmental mobility of fluorine probes localized inside of the nanoassembly. We showed the feasibility of this responsive polymeric system in 19F MRI applications.

These results show that subtle molecular lever alterations can be utilized to control the behavior of nanoscale materials and tune the properties for intended applications.

Available for download on Friday, February 01, 2019

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