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Document Type

Campus-Only Access for One (1) Year

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Polymer Science and Engineering

Year Degree Awarded

2018

Month Degree Awarded

September

First Advisor

Prof. E. Bryan Coughlin

Subject Categories

Materials Chemistry | Polymer Chemistry

Abstract

Multiblock copolymers have gained considerable attention due to their ability to offer immense potential for designing soft materials with complex architectures for diverse applications. The enlarged parameter space offered by these multiblock copolymers gives access to a wide variety of multiply continuous morphologies which can be used to produce highly ordered nanostructures. The investigation on multiblock copolymers has been subjected to two critical limitations: (i) A suitable synthetic strategy for accessing these structures and (ii) computational tools which can help in application driven design of these molecules. In this dissertation, the goal was to develop methodologies for the synthesis of multiblock copolymers with different architectures and understand how the variations in molecular architecture can influence macromolecular self-assembly.

In chapter 2, the concept of single molecule insertion (SMI) for precise insertion of functional molecules is presented. The molecule precisely inserts once within the polymer chain with high chain fidelity and provides functionalities for post-insertion modifications. A series of molecules satisfying the criteria for SMI based on their reactivity ratios with styrene and methyl methacrylate were examined and used to synthesize a series of multiblock polymers with complex architectures.

In chapter 3, a highly efficient synthetic methodology for synthesis of graft copolymers which lie along the continuum of a 3-arm star and A-B-C linear triblock copolymer has been described. The morphological characterization of the synthesized continuum graft copolymers is performed using SAXS, TEM, and DPD simulations. Interesting morphologies are observed for these continuum copolymers and projects them as interesting candidates to access new morphologies. Contrary to most of the work done on block copolymers, these structures are novel as their morphologies can be tuned keeping the φ and χ constant. This study helps in understanding of the effect of polymer architecture on the phase behavior of these graft copolymers and provides a novel pathway to tune the block copolymer morphologies.

In chapter 4, a series of PMMA-b-PtBS-b-P2VP and PtBA-b-PtBS-b-P2VP triblock copolymers with extending P2VP arm has been synthesized. The study helps in extending the concept of high χ-low N block copolymer system from diblock to triblock copolymers. The morphologies of the synthesized triblock copolymers were characterized using SAXS and TEM and morphologies with multiple domains and smaller feature size were observed. Also, the effect of extending chain length of P2VP arm on the phase diagram on these highly frustrated triblock copolymer systems was studied and the observed morphologies using SAXS and TEM were mapped with the theoretical predictions.

Available for download on Sunday, September 01, 2019

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