MSE PhD Proposal: Matthew Smith

Date: Thursday, April 23rd, 2015
Time: 3 PM to 5 PM
Location: Love Conference Room 210

Committee:

Baratunde Cola (MSE/ME/Advisor)
Kyriaki Kalaitzidou (MSE/ME/Advisor)
Elsa Reichmanis (ChBE)
David Bucknall (MSE)
Ken Gall (MSE/ME)

Title:  Processing-structure-property relationships in template fabricated polymer and polymer composite nanostructures

Abstract:

As electronic systems continue to shrink and become more energy dense, thermal dissipation is emerging as a roadblock to sustained performance enhancements.  In particular, thermal interface materials (TIMs) need improved mechanical compliance and thermal conductivity to meet the needs of next generation electronics.  Unfortunately, “soft” and mechanically compliant materials are plagued by low thermal conductivity due to molecular disorder which results in phonon scattering.  However, nanoscale confinement can be used to induce alignment in polymers and high conductivity fillers can be added to polymers, with the hope that a new class of soft and thermally conductive materials will be developed. The goal of this work is to enhance the thermal conductivity of polymer and composite structures so that they may be used in electronics packaging.  In particular, this work will explore the processing-structure-property relations in films of i) vertically aligned polymer nanotube arrays, ii) vertically aligned polymer/multiwall carbon nanotube (MWCNT) and polymer/boron nitride nanotube (BNNT) nanowire arrays, and iii) polymer infiltrated graphene foam composites. 

Polymer nanotube and polymer/MWCNT or polymer/BNNT composite nanowire arrays, which resemble thin films macroscopically, but exhibit properties that vary from their isotropic bulk film counterparts, are fabricated using solution and melt wetting of nanoporous alumina templates.  The thermal, wetting, and electrical properties of the template fabricated polymer nanotube and composite nanowire arrays are investigated as a function of template filling conditions.  Initial results demonstrate the achievement of superhydrophobic surfaces, orders of magnitude improvements in thermal and electrical conductivity, and the fabrication of polymer/MWCNT composite nanowires with MWCNTs distributed throughout the length of the nanowire.  Graphene foams, which can be fabricated through a simple laser writing process, are another nanomaterial investigated in this work.  Unlike the aforementioned composite materials, graphene foams exhibit a three dimensional carbon network that may provide a route for reduced interfacial phonon scattering.  Current efforts are underway to infiltrate these foams with polymer and to measure the composite films resulting electrical and thermal properties.  Finally, for each of the polymer and composite nanostructure materials mentioned, the application for next generation thermal interface materials and substrates for thermal management of electronic systems are being explored.