Actuating Single Wall Carbon Nanotube–Polymer Composites: Intrinsic Unimorphs

Autor: Jin Ho Kang, Robert C. Costen, Joycelyn S. Harrison, Cheol Park, Sharon E. Lowther
Rok vydání: 2008
Předmět:
Zdroj: Advanced Materials. 20:2074-2079
ISSN: 1521-4095
0935-9648
Popis: Electromechanical coupling effects in polymers have been routinely employed to create an array of sensors and actuators. The most dominant coupling effects originate from piezoelectric, electrostrictive, and electrostatic (also known as the Maxwell effect) mechanisms. To generate high displacements, electrostrictive and Maxwell effects are typically exploited because the strain in such polymers is a quadratic function of the applied electric field, whereas it is linear for piezoelectrics. However, the high compliance of most electrostrictive and electrostatic polymers limits their durability and output force and reduces their applicability. Owing to their low dielectric constants relative to ceramics, polymers typically require large applied electric fields to actuate. For strain amplification, several actuator concepts have been demonstrated including multilayer and bender designs. Most commercial actuators integrate design concepts, including unimorph, bimorph, and multimorph. These designs require extra processing steps and introduce extraneous layers such as adhesives and inactive, so-called ‘‘dummy’’, layers to convert longitudinal to bending strain. The incorporation of these adhesive and inactive layers reduces the magnitude of the actuation of a given actuation system significantly and often causes delamination. Furthermore, mismatches in the thermal expansion coefficients and mechanical properties among the adhesive, inactive, and active layers can cause additional adverse effects on the actuation performance. Here we introduce a novel electroactive single-walled carbon nanotube (SWNT)–polymer composite, an intrinsic unimorph, which can actuate to a large strain (2.6%) at relatively low driving voltages (
Databáze: OpenAIRE
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