Physical Sciences and Mathematics Commons^™

The Importance Of Chain Connectivity In The Formation Of Non-Covalent Interactions Between Polymers And Single-Walled Carbon Nanotubes And Its Impact On Dispersion, Dias Linton

Doctoral Dissertations

Polymer nanocomposites have garnered incredible promise in the field of material science due to the excellent mechanical strength, thermal and electrical conductivities of the nanoparticles and the extension of these properties to the processing flexibility inherent to plastics. However, practical realization of these nanoparticle-based materials has been hindered by the tendency of these nanoparticles to aggregate as a result of strong inter-particle forces. In this dissertation, we investigate the formation of non-covalent charge transfer interactions between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial adhesion and homogeneity of nanocomposites without modifying the SWNT native surface.

Nanocomposites …

The Impact Of Non-Covalent Interactions On The Dispersion Of Fullerenes And Graphene In Polymers, Say Lee Teh

Masters Theses

The work presented in this dissertation attempts to form an understanding of the importance of polymer connectivity and nanoparticle shape and curvature on the formation of non-covalent interactions between polymer and nanoparticles by monitoring the dispersion of nanoparticles in copolymers containing functionalities that can form non-covalent interactions with carbon nanoparticles.

The first portion of this study is to gain a fundamental understanding of the role of electron donating/withdrawing moieties on the dispersion of the fullerenes in copolymers. UV- Vis spectroscopy and x-ray diffraction were used to quantify the miscibility limit of C60 fullerene with the incorporation of electron donor-acceptor interactions …

Polymeric Loop Formation At Hard And Soft Interfaces, Earl Ashcraft

Doctoral Dissertations

Copolymers are used to increase the interfacial strength of immiscible components and suppress recombination of the minor phase by steric hindrance. The experiments conducted in these studies are designed to investigate in situ polymer loop formation at soft interfaces and functionalized nanotube surfaces. Block copolymers are the most effective type of copolymer for compatibilization because they extend perpendicular to the interface, allowing good entanglement with the homopolymer chains. Multiblock copolymers are more effective than diblock copolymers for strengthening the interface because they can cross the interface multiple times, forming “loops” in each phase that provide entanglement points for the homopolymer. …

Supported Aqueous-Phase Catalysis For Atom Transfer Radical Polymerization, Ravi Aggarwal

Doctoral Dissertations

Atom transfer radical polymerization (ATRP) which utilizes transition metal based catalysts is a versatile methodology for the synthesis of a wide spectrum of polymers with controlled architectures. However, high concentrations of soluble catalyst required in an ATRP process makes the final polymer colored and toxic. Thus, the catalyst removal/reduction/recycling remains a challenge in the field of ATRP. Supported catalysts on insoluble solids such as silica gel, polystyrene beads, etc. have been used in ATRP to facilitate the catalyst recovery and recycling. However, the ability of the supported catalysts to mediate a polymerization is substantially reduced due to their reduced mobility …

Hairy Particles: Polymer Brush-Supported Organocatalysts And Asymmetric Mixed Homopolymer Brushes, Xiaoming Jiang

Doctoral Dissertations

This dissertation presents the synthesis and studies of polymer brush-supported organocatalysts and asymmetric mixed homopolymer brushes grafted on particles. The brushes were synthesized from initiator-functionalized particles by surface-initiated “living” radical polymerizations.

Polymer brush-supported organocatalysts were designed to combine the advantages of both soluble polymer- (high activity) and crosslinked insoluble polymer-supported catalysts (recyclability). Chapter 1 describes the synthesis of a polymer brush-supported 4-N,N-dialkylaminopyridine (DAAP) catalyst from initiator-functionalized latex particles by surface-initiated nitroxide-mediated radical polymerization (NMRP). The hairy particles efficiently catalyzed the acylation of secondary alcohols and Baylis-Hillman reaction and were recycled  six times with no or negligible decrease in the …