CHAPTER 11: Polymer Nanocomposites: Conductivity, Deformations and Photoactuation
Published:15 May 2013
J. E. Marshall, Y. Y. Huang, and E. M. Terentjev, in Responsive Photonic Nanostructures: Smart Nanoscale Optical Materials, ed. Y. Yin, The Royal Society of Chemistry, 2013, pp. 292-329.
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Advances in functionality and reliability of carbon nanotube (CNT) composite materials require careful formulation of processing methods to ultimately reach the desired properties of the composite. There is a strong correlation between the processing, the resulting microstructure and the physical properties of the composite. Here, we offer a review of the dispersion processes of pristine (noncovalently functionalized) CNTs in a solvent or a polymer solution. We adapt relevant theoretical analysis to guide the dispersion design and selection, from the processes of mixing/sonication to the application of surfactants for stabilization, to the final testing of composite properties – specifically focusing on the bulk and surface conductivity. When CNT segments are well aligned in the elastomer matrix, the composite shows a strong mechanical response to light absorbed by CNTs. We call this reversible effect photomechanical actuation. To enhance the alignment, one should use a system with natural orientational order: the liquid‐crystalline elastomers (LCE). Many LCEs reported in the literature will reversibly contract in one dimension in response to a temperature change. For practical applications, triggering of actuation by light is a more useful technology than heat due to the achievable speed and localization of the response. We review the methods of sensitization of LCEs to light by CNTs, which absorb light over a large range of wavelengths and convert it into local heat, thus triggering the required phase changes in the LCE and the associated photoinduced actuation.