Polymers with Multishape Memory Controlled by Local Glass Transition Temperature

Abstract

A multishape memory polymer with flexible design capabilities is fabricated by a very simple method. Local glass transition temperatures of a loosely cross-linked polymer film are changed by immersing sections of the film in a cross-linker solution with a different concentration. Each section memorizes a temporary shape, which recovers its permanent shape at a different recovery temperature depending on the local glass transition temperature. As a base polymer, we chose a network polymer prepared by a Diels–Alder reaction between poly­(2,5-furandimethylene succinate) (PFS) and 1,8-bis-maleimidotriethyleneglycol (M₂). Quintuple shape memory behavior was demonstrated by a PFS/M film with four sections with distinct glass transition temperatures. The number of temporary shapes was determined by the number of different M₂ solutions. Furthermore, owing to the reversibility of the Diels–Alder reaction, the permanent shape was rewritable