Shape Actuation via Internal Stress-Induced Crystallization of Dual-Cure Networks
2015; American Chemical Society; Volume: 4; Issue: 1 Linguagem: Inglês
10.1021/mz500773v
ISSN2161-1653
AutoresYuan Meng, Jisu Jiang, Mitchell Anthamatten,
Tópico(s)Advanced Materials and Mechanics
ResumoWe demonstrate a single-phase, two-way shape actuator that, in the absence of an external load, elongates upon cooling and reversibly contracts upon heating. In a simple and straightforward process, a partially cross-linked, semicrystalline poly(ε-caprolactone) (PCL) network is melted, stretched to several hundred percent strain, and further cross-linked. Upon removal of the applied load, the elastic double network adopts a "state-of-ease" that retains part of its former strain. When cooled, internal stress-induced crystallization causes further elongation of configurationally biased chains. When heated, crystallites melt, and the sample returns to its equilibrium state-of-ease. Under optimized conditions, reversible actuation >15% strain can be reproducibly achieved, and samples can be cycled multiple times with highly uniform actuation with no observable creep. The mechanism behind such actuation was further confirmed via calorimetry and X-ray scattering.
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