Programming\nof Shape Memory Natural Rubber for Near-Discrete\nShape Transitions

Abstract

Typical\nshape memory polymers are hot-programmed and show a shape\ntransition over a broad temperature range of 10 K and more. Cold-programmed\nshape memory natural rubber (SMNR) recovers more than 80% of its original\nshape within 1 K. The trigger point can be increased upon aging the\nstretched SMNR over several weeks without losing the narrow trigger\nrange. This process can be accelerated by treatment of the stretched\nSMNR with nonaffine solvent vapors. Affine solvent vapors of low concentrations\nafford higher trigger points than that achieved by aging. This way,\neven higher cross-linked natural rubber can be cold-programmed.