Enhancing Functional and Structural Properties of Polymer Nanocomposites by Controlling Dispersion and Interfaces

University Of Tennessee Knoxville, Knoxville TN

Investigators

Abstract

TECHNICAL ABSTRACT Dispersing nanoparticles, such as carbon nanotubes, in a polymer matrix offers a promising method to create new materials with novel properties. Unfortunately, most nanoparticles do not homogeneously disperse in a polymer matrix, and thus the fabricated mixtures rarely attain the targeted properties. This project will seek to overcome this limitation by developing an understanding of how intermolecular interactions between polymer and pristine nanotubes can be accomplished and optimized. This will be realized by determining the ability of various polymer-bound functional groups to form electron donor-acceptor (EDA) interactions with pristine single-walled nanotubes (SWNT) and correlating the nature and extent of this interaction to the dispersion of the SWNT in a polymer matrix and to the structural and functional properties of the ultimate nanocomposite. Additionally, the most promising functional groups that form EDA complexes with SWNT will be incorporated into copolymers as a minor component. In these nanocomposites, the extent of non-covalent interaction formation in the nanocomposite will be monitored and correlated to the dispersion of the nanofiller in the polymer matrix and to the nanocomposite properties. This copolymerization will broaden the range of polymer structures, and thus targeted functionality, that can be incorporated in well-dispersed polymer nanocomposites. The design of the experiments builds on our previous NSF-supported work that demonstrates that optimizing non-covalent interactions (hydrogen bonding) between polymer and nanoscale filler can dramatically improve the dispersion and thermal, electronic, and structural properties of the resultant nanocomposite. Thus, a series of experiments will be completed that utilizes our expertise in non-covalent polymer-nanofiller interactions to develop methods to rationally tune the interfacial interaction between a nanofiller and polymer matrix to improve the homogeneity and properties of the resultant nanocomposite, while preserving the interfacial structure required for a targeted functionality. NON-TECHNICAL ABSTRACT Homogeneous mixing nano-sized fillers with a polymer enables the production of new materials with a range of properties that are not accessible with polymers alone. For instance, the inclusion of clays in a polymer matrix has been shown to improve its heat deflection temperature, flame resistance, gas permeability and strength. Alternatively, the incorporation of carbon fullerenes or nanotubes in a conjugated polymer matrix improves its ability to turn sunlight into energy. Unfortunately, creating this homogeneous mixture of polymers and nanoparticles is difficult, as most nanoparticles will not effectively disperse in the polymer matrix. Improved mixing behavior has been realized by modifying the surface of the nanoparticle, however this alteration often results in a decrease in its desired properties. This project will seek to overcome this limitation by developing methods to incorporate attractive interactions between the polymer and nanoparticle, without altering the structure of the nanoparticle, with the ultimate goal of using these attractive interactions to improve the dispersion of the nanoparticles in the polymer matrix and the properties of the final nanocomposite. This project will also train local high school science teachers in polymers, educate the public regarding the contribution of materials to technological advances via a public outreach website (www.factofthematter.org), and expedite the transfer of the guidelines and fundamental understanding garnered from this project to commercially viable technologies by collaborating with industry.