Two-way shape changing polymers are attractive in recent years. In this short communication, carbon black (CB)/shape memory polyurethane (SMPU)-elastic polyurethane (EPU) laminated composite is prepared and electro-active two-way shape changing behavior is reported for the first time. First, the CB/SMPU composite demonstrates good electro-active shape recovery due to good electricity conduction. When the CB/SMPU composite film is elongated and form polymer laminates by combining with EPU substrate, the resulted CB/SMPU-EPU polymer laminate shows electro-active two-way shape changing behavior, e.g., bending by applying electric current, and reverse bending upon cooling without electric current. POLYM. COMPOS. 36:439–444, 2015. © 2014 Society of Plastics Engineers

Researchers are actively developing shape memory polymers (SMPs) for smart biomaterials. This paper reports a new SMP system synthesized from biocompatible 2-(dimethylamino) ethyl methacrylate (DMAEMA), butyl acrylate (BA) and tri(ethylene glycol) divinyl ether (TDE). Preliminary results show that the DMAEMA-co-BA-co-TDE copolymers form micelles in aqueous solution due to chemical crosslinking and hydrophobicity. The micelle size decreased with the increase in the BA content since the hydrophobicity of copolymers increases with the increase of BA content. The resulting polymer films contain–N(CH₃)₂ functional groups for further biomaterial applications. The thermal stability of DMAEMA-co-BA-co-TDE copolymers is determined by the DMAEMA structure and content. Moreover, the copolymers form micro-phase-separated structures containing a reversible amorphous soft phase, and the storage moduli decreases significantly around T_g. Therefore, good thermal-induced shape memory effects are achieved in the DMAEMA-co-BA-co-TDE copolymers by adjusting the BA content. This work proposes a new strategy for designing smart biomaterials using a biocompatible monomer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42312.

In this study, a series of shape memory polyurethanes (SMPUs) were synthesized successfully by the bulk polymerization method from liquefied 4,4′-diphenylmethane diisocyanate (L-MDI), 1,4-butanediol (BDO) and polyethylene glycol (PEG). The influence of the hard segment content (HSC) on the structure, morphology, properties and biocompatibility of PEG based SMPUs (PEGSMPUs) was carefully investigated. The results show that a microphase separation structure composed of a semicrystalline soft phase and an amorphous hard phase is formed in the PEG6000/L-MDI/BDO system. Crystallization of the PEG soft segment is influenced by the hard segments. The PEG semicrystalline soft phase serves as a reversible phase while the L-MDI−BDO hard segment acts as physical netpoints. Finally, a cyclic tensile test shows that all PEGSMPUs have good shape recovery (e.g. above 80%), whereas good shape fixity can only be achieved when the HSC is less than 35 wt%. The Cell Counting Kit 8 assay also demonstrates that only PEGSMPUs containing less than 40 wt% HSC have low cytotoxicity. It is thus concluded that PEGSMPUs bearing both good shape memory effects and good biocompatibility can be used as shape memory materials for biomedical applications when the HSC is less than 35 wt%. © 2014 Society of Chemical Industry

This article demonstrates a comparative investigation about the effect of diisocyanate on pyridine containing shape memory polyurethanes (Py-SMPUs), which are synthesized with N,N-bis(2-hydroxylethyl)isonicotinamide (BINA) and four different diisocyanates: 1,6-hexanediisocyante (HDI), isophorone diisocyanate (IPDI), methylene diphenyl diisocyanate (MDI), and tolylene diisocyanate (TDI). Results show that all BINA–SMPU systems have amorphous reversible phase. Comparatively, the MDI–BINA and TDI–BINA systems show higher T_g; and the HDI–BINA and IPDI–BINA systems show better thermal stability. In addition, the HDI–BINA and the IPDI–BINA systems exhibit good thermal-induced shape memory effect and good moisture-sensitive shape memory effect due to their better moisture absorption properties. Particularly, the HDI–BINA system has better response speed and better shape recovery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40721.

This article presents a facile preparation method of shape memory polyurethane (SMPU) by polyurethane blending from commercial thermoplastic polyurethane (PUA) with designed polyurethane (PUB). Structure, morphology, and shape memory behaviors of SMPU blends are investigated systematically. The results show that the PUB and PUA are miscible in the SMPU blends. When the PUB content is higher than 40 wt %, the T_g of SMPU blends is adjusted to above room temperature. As the PUA content increases, the PUA phase changes gradually from a droplet-like dispersion phase to continuous soft phase, whereas the PUB phase changes from a continuous hard phase to a droplet-like dispersion hard phase. SMPU blends show good shape memory effect when the PUA is blended with more than 40 wt % PUB. Thus, the commercialization of SMPU can be promoted greatly through the polyurethane blending from the commercial thermoplastic polyurethanes with polyurethane containing higher hard segment content. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4047–4053, 2013