Quadruple-shape memory properties of PFSA. (a) Visual demonstration. S0: permanent shape; S1: first temporary shape (Td1: 140 ◦C); S2: second
temporary shape (Td2: 107 ◦C); S3: third temporary shape (Td3: 68 ◦C); S2rec: recovered second temporary shape (Tr1: 68 ◦C); S1rec: recovered first temporary shape (Tr2: 107 ◦C); S0rec: recovered permanent shape (Tr3: 140 ◦C). (b) Quantitative thermal mechanical cycle (Td1 = Tr3 = 140 ◦C, Td2 = Tr2 = 90 ◦C,
Td3 = Tr1 = 53 ◦C).
Ref. [75], Copyright 2010. Reproduced with permission from Nature Publishing Group.