Shape memory polymers are attractive for both science and industrial application. In this article, a series of pyridine-containing supramolecular shape memory polyurethanes (Py-SMPUs) with various diphenylmethane diisocyanate–butanediol (MDI–BDO) contents are synthesized from the 1,6-hexamethylene diisocyanate (HDI), N,N-bis(2-hydroxylethyl) isonicotinamide (BINA), BDO, and MDI. Then, they are investigated systematically using FT-IR, DSC, DMA, WAXD, and shape memory testing. The results show that the addition of MDI–BDO segment improves the strength of hydrogen bonding of Py-SMPUs. It promotes the formation of hard domains, but not influences the phase-separation structure, the intensity, and distribution of physical netpoints. In addition, the MDI–BDO segment improves the rubber modulus and drops the energy loss of Py-SMPUs. However, it does not influence the shape memory behaviors which are mainly influenced by the BINA content. If the BINA content is beyond 30 wt%, good shape memory effect can be achieved in the BINA–HDI–BDO–MDI system; and high shape recovery force can be obtained by increasing the MDI–BDO segment.
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This study was financially supported from the Natural Science Foundation of China (No. 50803037)), Natural Science Foundation of Guangdong (No. 2008211), and the PhD studentship of Hong Kong Polytechnic University. The authors also would like to thank Prof. Jean-Marie Lehn, the Nobel Prize Laureate in 1987, for his guidance.
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