4D printable shape memory polyurethane with quadruple hydrogen bonding assembly

Abstract Four‐dimensional (4D) printing is an emerging technology for fabricating customizable tissue engineering implants. 4D printed implants with shape memory properties are expected to provide new application opportunities for minimally invasive surgery. A great challenge is to prepare the biodegradable materials with robust mechanical properties for 4D printing ink. Herein, biodegradable thermoplastic polyurethanes (TPUs) based on IPDI, PEG, PCL, and diols with UPy motifs are synthesized. The pendant UPy motifs can dimerize to form physical crosslinking by quadruple hydrogen bonding assembly, accompanying with significant improving the mechanical properties, self‐healing capability and shape memory effect. With an optimal UPy content, the PU‐U2‐25% shows robust mechanical properties and much better shape memory effect compared with the PU‐U2‐0% without UPy. Moreover, the TPUs show a facile processing at relative low temperature approximately 100 °C which avoid degradation at high processing temperature. Combined with the good processability, self‐healing capacity and shape memory effect of the PU‐U2‐25%, we primary demonstrated its 4D printing potential for various specimens. This work proposed a new strategy to design TPUs integrating the merits of linear and pendant physical crosslinking motifs to obtained excellent comprehensive properties, which would develop the 4D printable materials for applications of personalized and minimally invasive treatment.