Letter abstract
Nature Materials 3, 115 - 120 (2004)
Published online: 25 January 2004 | doi:10.1038/nmat1059
Subject Categories: Composites | Polymers | Mechanical properties | Nanoscale materials
Remotely actuated polymer nanocomposites—stress-recovery of carbon-nanotube-filled thermoplastic elastomers
Hilmar Koerner1, Gary Price1, Nathan A. Pearce2, Max Alexander3 & Richard A. Vaia3
Stimuli-responsive (active) materials undergo large-scale shape or property changes in response to an external stimulus such as stress, temperature, light or pH1, 2. Technological uses range from durable, shape-recovery eye-glass frames, to temperature-sensitive switches, to the generation of stress to induce mechanical motion3, 4, 5, 6, 7, 8, 9. Here, we demonstrate that the uniform dispersion of 1–5 vol.% of carbon nanotubes in a thermoplastic elastomer yields nanocomposites that can store and subsequently release, through remote means, up to 50% more recovery stress than the pristine resin. The anisotropic nanotubes increase the rubbery modulus by a factor of 2 to 5 (for 1–5 vol.%) and improve shape fixity by enhancing strain-induced crystallization. Non-radiative decay of infrared photons absorbed by the nanotubes raises the internal temperature, melting strain-induced polymer crystallites (which act as physical crosslinks that secure the deformed shape) and remotely trigger the release of the stored strain energy. Comparable effects occur for electrically induced actuation associated with Joule heating of the matrix when a current is passed through the conductive percolative network of the nanotubes within the resin. This unique combination of properties, directly arising from the nanocomposite morphology, demonstrates new opportunities for the design and fabrication of stimuli-responsive polymers, which are otherwise not available in one material system.
- Nonmetallic Materials Division, University of Dayton Research Institute, 300 College Park Ave, Dayton, Ohio 45469, USA
- Miami University, 501 E. High St. Oxford, Ohio 45056, USA
- Materials and Manufacturing Directorate, 2941 P St, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
Correspondence to: Richard A. Vaia3 e-mail: richard.vaia@wpafb.af.mil
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