Triple-Shape Effect with Adjustable Switching Temperatures in Crosslinked Poly[ethylene-co-(vinyl acetate)]

A triple-shape capability of copolymer networks enabling a variation of the two switching temperatures T(sw)s by purely physical functionalization is introduced. The polymer networks obtained by covalently crosslinking of poly[ethylene-co-(vinyl acetate)] exhibit a broad melting transition. The infl uence of the two deformation temperatures T(deform)s applied during programming of the triple-shape effect (TSE) on the two T(sw)s is explored. Interestingly, it turns out that the deformation geometry plays an important role in the realizability of this concept. Tensile deformations allow adjusting only one T-sw in the lower melting temperature range of 45 to 60 degrees C, whereas in bending tests, both T(sw)s can be varied. Finally, two independent TSEs associated to four different T(sw)s between 45 and 90 degrees C can be realized in the same specimen. Shape fi xity and shape recovery ratios generally exceed 90%, demonstrating an excellent performance of the triple-shape function.