A novel method to synthesize polyurethane-urea acrylate with high strength and toughness

Photocurable oligomer with comprehensive mechanical performance has received increasing attention. However, it is an ongoing challenge to prepare strong and tough photocurable oligomer due to the well-known trade-off between strength and toughness. In this work, a novel strategy has been developed to synthesize polyurethane-urea acrylate (PUUA) with high strength and toughness. In our strategy, a new diol containing urea group was firstly synthesized, which was then used as chain extender to prepare PUUA. The employment of diol containing urea group to prepare PUUA can avoid the direct reaction between diamine and diisocyanate in the traditional synthetic strategy of PUUA. By changing the molecular structure of the chain extender, PUUA with different side chain was synthesized. The successful synthesis of PUUA was confirmed by FTIR and 1H NMR. The UV-cured PUUA film exhibited both high mechanical strength (31 MPa) and high toughness (39.5 MJ m−3), which was 1.24 and 1.45-fold increase compared with polyurethane acrylate (PUA) film without urea group. The simultaneously enhanced mechanical strength and toughness of PUUA film should be attributed to the formation of microphase separation, which has been proved by small-angle X-ray scattering (SAXS) test. This research represents an important and universal strategy to prepare PUUA with high mechanical strength and toughness.