Ultralow Thermal Conductivity in Organoclay Nanolaminates Synthesized via Simple Self-Assembly
Abstract
Because interfaces impede phonon transport of thermal energy nanostructuring can transform fully dense solids into ultralow thermal conductivity materials. Here we report a simple self-assembly approach to synthesizing organoclay nanolaminates with cross-planar thermal conductivities below 0.10 W m(-1) K(-1)-a 5-fold decrease compared to unmodified clay. These organoclays are produced via alkylammonium cation exchange with colloidally dispersed montmorillonite clay sheets followed by solvent casting. Time-domain thermoreflectance (TDTR) is used to evaluate the thermal conductivity of the organoclay nanolaminates. Variations in both organic layer thickness and cation chemistry are investigated. At these interface densities (1.0-1.5 interfaces/nm), we demonstrate that thermal conductivity is relatively independent of nanolaminate spacing. A simple series resistance model describes the behavior and gives an interfacial thermal conductance value of approx. 150 MW m(-2) K(-1) for the organic/clay interface, consistent with similar organic-inorganic interfaces. The wide range of compositional substitutions and structural variations possible in these materials, make organoclays a versatile new platform for investigating the underlying physics of nanolaminate structures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 17, 2013
- Accession Number
- ADA587397
Entities
People
- David G. Cahill
- Ian P. Blitz
- Mark D Losego
- Paul V Braun
- Richard A. Vaia
Organizations
- University of Illinois Urbana–Champaign