Polylactide-based polyurethane shape memory nanocomposites (Fe 3 O 4 /PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe 3 O 4 nanoparticles in apolymer matrix. A homogeneous distribution of Fe 3 O 4 nanoparticles in the polymer matrix was obtained fornanocomposites with low Fe 3 O 4 loading content. A smallagglomeration was observed fornanocomposites with 6 wt% and 9 wt% loading content, leading to a smalldecline in themechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites alsoexhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with anincrease inthe loading content of Fe 3 O 4 nanoparticles due to animprovement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential applicationin biomedical areas such as intravascular stent.

A facile method to prepare triple‐shape memory polymers was developed by blending polyurethane and polylactide–polytetramethylene with well‐separated glass transition temperatures. The thermal properties of the blends were characterized using modulated differential scanning calorimetry and differential scanning calorimetry. Field emission scanning electron microscopy, Fourier transform infrared spectroscopy and wide‐angle X‐ray diffraction were used to characterize the microstructures and crystal structures of the blends. The mechanical properties were also evaluated. The versatile triple‐shape memory effect and quantitative shape memory response were evaluated by consecutive thermal mechanical experiments based on a two‐step programming process and subsequent progressive thermal recovery. The results show that the blends have phase‐separated microstructures resulting in an ability to fix two temporary shapes independently and can recover to their original shapes sequentially. The blends have excellent triple‐shape memory properties and may have some applications in multi‐shape coatings, adhesives, films and temperature sensing or actuating elements. © 2015 Society of Chemical Industry

A series of random copolymers (PCLAs) were synthesized by ring-opening polymerization of D,L-lactide (LA) and ε-caprolactone (CL) with different molar ratios. PCLA based polyurethanes (PCLAUs) were obtained by chain-extending of PCLA and polytetramethylene ether (PTMEG) with hexamethylene diisocyanate (HDI). All the PCLAUs exhibit good shape memory properties with high shape fixity ratios above 98% and shape recovery ratios above 82% in the first cycle and 91% in the second cycle. PCLAUs with less CL content show faster recovery speed and PCLAUs with more CL content show higher shape recovery ratio. The trigger temperature can be tuned or controlled around body temperature by adjusting the molar ratio of LA to CL. The PCLAUs have potential applications in implant biomedical devices, especially for minimally invasive deployable devices.

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