Abstract:
A self-healing photosensitive polyurethane acrylate (PUTA), containing bulky urea bonds and crystalline soft segments, was designed and prepared based on the dynamic reversibility of the blocking agent. The UV-cured material presents high elasticity, good mechanical property, self-healing and shape memory functions. With the increase of soft segment content, the compatibility of soft and hard segments is improved. Combined with the thermal results of Dynamic Mechanical Analysis (DMA) and Differential Scanning Calorimetry (DSC), the best healing temperature of PUTA is 80 ℃, which was consistent with the glass transition temperature (
Tg) of hard segment. After heat treatment, the healing efficiency of materials can reach 70% (the tensile strength and elongation are 3.58 MPa and 250%, respectively). The dynamic reversible characteristics of urea bond with large steric hindrance make the material better self-healing performance. After being thermal-stimulated, the urea bond molecules at the fracture place of the PUTA sample undergo dynamic exchange and reaction, thus completing the healing process of the material. The crystalline transformation of soft segment endows the material with properties of remolding and shape memory. Besides, the shape recovery can be completed quickly after heating. Specifically, for PUTA with polycaprolactone (PCL,
Mn=4000) as soft segment, the shape recovery can be completed within 5 min at 80 ℃. The prepared material has intelligent response characteristics in thermo-responsive behavior of self-healing and shape memory. Besides, the higher the content of the soft segment is, the better the crystallinity and the stronger the shape memory ability are. Combined with UV curing 3D printing technology, it is expected to play a role in the field of customized intelligent wearable devices and biomedical materials.