ORIGINAL RESEARCH Self-healing nanocomposite hydrogels based on modified cellulose nanocrystals by surface-initiated photoinduced electron transfer ATRP Liangjiu Bai . Xinyan Jiang . Zhixiang Sun . Zhaoxia Pei . Anyao Ma . Wenxiang Wang . Hou Chen . Huawei Yang . Lixia Yang . Donglei Wei Received: 27 December 2018 / Accepted: 22 April 2019 Ó Springer Nature B.V. 2019 Abstract Self-healing hydrogels with excellent toughness and mechanical strength are particularly desirable for practical application. In this paper, green and environmentally friendly cellulose nanocrystals (CNCs) were successfully modified on the surface via metal-free photoinduced electron transfer atom trans- fer radical polymerization (PET-ATRP). Surface-ini- tiated PET-ATRP was achieved by using 4-vinylpyridine (4VP) as functional monomer, 10-phenylphenothiazine (Ph-PTZ) as photocatalyst and ultraviolet light (365 nm) as light source, respectively. The prepared P4VP-CNCs hybrid mate- rials (CNCs@P4VP) were used as green reinforcement to obtain self-healing nanocomposite hydrogels by electrostatic interactions. As a result, the nanocom- posite hydrogels displayed outstanding mechanical (6.6 MPa at a strain of 921.6%) and self-healing (85.9% after repairing 6 h) properties. This work provides a promising green method for designing novel self-healing nanocomposite hydrogels with high strength. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10570-019-02449-2) con- tains supplementary material, which is available to authorized users. L. Bai (&)  X. Jiang  Z. Sun  Z. Pei  A. Ma  W. Wang (&)  H. Chen  H. Yang  L. Yang  D. Wei Collaborative Innovation Center of Shandong Province for High Performance Fibers and Their Composites, School of Chemistry and Materials Science, Ludong University, Yantai 264025, China e-mail: bailiangjiu@ldu.edu.cn W. Wang e-mail: wangwenxiang@ldu.edu.cn 123 Cellulose https://doi.org/10.1007/s10570-019-02449-2