Quantitative Predictions of Shape-Memory Effects in Polymers.

Hornat, Chris C; Yang, Ying; Urban, Marek W · Adv Mater · 2017

basic_science · Level V

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Abstract

Unique shape-memory transitions manifested by directional extension and subsequent retraction in polymers are attributed to stored conformational entropy. This behavior is quantified in terms of stored (ΔS <sub>S</sub> ) entropic energy density, the maximum strain (ε<sub>max</sub> ), and stress (σ<sub>SF</sub> at ε<sub>max</sub> ). This concept allows quantitative assessments of the shape-memory effect (SME) and can be utilized in any material that exhibits a glass-transition temperature (T <sub>g</sub> ) and a rubbery plateau.