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Hierarchical Cross-Linked Poly(caprolactone-co-urethane) toward Connective Tissue-like Properties and Multifunctional Integration

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journal contribution
posted on 12.11.2019, 02:29 by Yawei Sun, Zhao Liu, Fang Chen, Mi Xu, Jinli Zhang, Wei Li
It is a great challenge to regulate the mechanical properties precisely with both softness and toughness so as to match the requirements of various flexible device applications. Inspired by the three-dimensional network of collagen in connective tissues, a novel biopolymer poly­(caprolactone-co-urethane) with hierarchical cross-links was synthesized on the basis of polycaprolactone (PCL) and composite chain extenders of tannic acid (TA) and 1,4-butanediol (BDO). The biopolymer P­(CL-TAx/BDOy) possesses both physical and chemical cross-links in coordination with phase separation microstructure, sensitive to the molar ratio of TA/BDO. The optimal P­(CL-TA1/BDO1) shows connective tissue-like properties, possesses an initial modulus less than 0.5 MPa but high toughness (61.2 MJ m–3), unique adhesive property, and shape memory behavior. A flexible actuator was prepared by P­(CL-TA1/BDO1), exhibiting the shape transformation behavior by an electricity stimulation. This work provides a novel facile method to design biopolymers, including tuning the mechanical properties and integrating multifunctions through the hierarchical cross-link strategy.