Polymers with multishape memory controlled by local glass transition temperature

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.