Controlling polymer network topology

• Main Author: Gu, Yuwei,Ph.D.Massachusetts Institute of Technology.
• Other Authors: Jeremiah A. Johnson.
• Format: Others
• Language: English
• Published: Massachusetts Institute of Technology 2019
• Subjects: Chemistry.
• Online Access: https://hdl.handle.net/1721.1/122851

Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2019 === Cataloged from PDF version of thesis. === Includes bibliographical references. === Chapter 1: Introduction to Polymer Network Topology on a (Macro)Molecular Level Polymer network topology, comprising the ways in which strands and junctions are connected in polymer networks, plays a critical role in dictating many material properties. Here we discuss classical challenges in the field and review existing strategies to characterize and manipulate polymer network topology from a (macro)molecular level. Chapter 2: Semibatch Monomer Addition as a General Method to Tune and Enhance the Mechanics of Polymer Networks via Loop-defect Control In this chapter we introduce semibatch monomer addition as a general strategy to reduce/control an important topological feature at short length scale-primary loops, thus providing materials with tunable and significantly improved mechanical properties without changing their composition. === Chapter 3: Leaving Groups as Traceless Topological Modifiers for Controlling Topological Structure in Chemically Identical Polymer Networks Here we report "traceless topological modification" as a general approach to control an important long length-scale topological feature-junction distribution. Using self-assembled structures as templates that are not themselves incorporated into the network, our method enables us to synthesize truly topologically isomeric networks with drastically different macroscopic properties. Chapter 4: Photoswitching Topology in Polymer Networks with Metal-Organic Cages as Crosslinks Based on our works in Chapter 2 and Chapter 3, we further explored topology as the central design principle to create novel functional materials. === In this chapter we introduce topology switching via cooperative self-assembly as a design principle to reversibly alter multiple network properties simultaneously and enable the preparation of one material that can exist in multiple topological states. Chapter 5: Living Additive Manufacturing: Transformation of Parent Gels into Diversely Functionalized Daughter Gels Made Possible by Visible Light Photoredox Catalysis Our ability to control polymer network topology has been further enhanced by developing living additive manufacturing as an effective strategy to expand the original topology of parent networks in a photo-growth fashion. This approach enables us to transform the mechanical/physical properties of parent networks post-synthetically. === Chapter 6: polyMOF Nanoparticles: Dual Roles of a Multivalent polyMOF Ligand in Size Control and Surface Functionalization Here we present a novel approach to synthesizing well defined metal-organic framework nanoparticles (MOF NPs), where the size control and surface functionalization of MOF-5 NPs were simultaneously achieved using multivalent polyMOF ligands. === by Yuwei Gu. === Ph. D. in Organic Chemistry === Ph.D.inOrganicChemistry Massachusetts Institute of Technology, Department of Chemistry