A triple-shape memory polyurethane (TSMPU) with poly(ε-caprolactone) -diols (PCL-diols) as the soft segments
and diphenyl methane diisocyanate (MDI), N,N-bis (2-hydroxyethyl) cinnamamide (BHECA) as the hard segments
was synthesized via simple photo-crosslinking of cinnamon groups irradiated under λ > 280 nm ultraviolet (UV) light.
Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H-NMR) and ultraviolet-visible absorption spectrum (UV−vis) confirmed the chemical structure of the material. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results demonstrated that the photocrosslinked polymer possessed two transition temperatures, one is due to the melting point of the soft segment PCL-diols, and the other is due to the glass transition temperature. All these contributed to the cross-linked structure of the hard segments and resulted in an excellent triple-shape memory effect. Alamar blue assay showed that the material has good non-cytotoxicity and can be potentially used in biomaterial devices. 


Lin Wang,Xifeng Yang,Hongmei Chen,Tao Gong,Wenbing Li,Guang Yang,and Shaobing Zhou.


ACS Appl.Mater.Interfaces,5(21),10520-10528(2013)