1 research outputs found
Preparation, Characterization, and Mechanism for Biodegradable and Biocompatible Polyurethane Shape Memory Elastomers
Thermally induced
shape memory is an attractive feature of certain
functional materials. Among the shape memory polymers, shape memory
elastomers (SMEs) especially those with biodegradability have great
potential in the biomedical field. In this study, we prepared waterborne
biodegradable polyurethane SME based on polyÂ(ε-caprolactone)
(PCL) oligodiol and polyÂ(l-lactic acid) (PLLA) oligodiol
as the mixed soft segments. The ratio of the soft segments in polyurethanes
was optimized for shape memory behavior. The thermally induced shape
memory mechanism of the series of polyurethanes was clarified using
differential scanning calorimeter (DSC), X-ray diffraction (XRD),
and small-angle X-ray scattering (SAXS). In particular, the in situ
SAXS measurements combined with shape deformation processes were employed
to examine the stretch-induced (oriented) crystalline structure of
the polyurethanes and to elucidate the unique mechanism for shape
memory properties. The polyurethane with optimized PLLA crystalline
segments showed a diamond-shape two-dimensional SAXS pattern after
being stretched, which gave rise to better shape fixing and shape
recovery. The shape memory behavior was further tested in 37 °C
water. The biodegradable polyurethane comprising 38 wt % PCL segments
and 25 wt % PLLA segments and synthesized at a relatively lower temperature
by the waterborne procedure showed ∼100% shape recovery in
37 °C water. The biodegradable polyurethane SME also demonstrated
good endothelial cell viability as well as low platelet adhesion/activation.
We conclude that the waterborne biodegradable polyurethane SME possesses
a unique thermally induced shape memory mechanism and may have potential
applications in making shape memory biodegradable stents or scaffolds