We present a facile strategy for the fabrication of mechanically tough and self-recoverable nanocomposite hydrogels reinforced by surface-modified cellulose nanocrystals. Polyacrylamide grafted cellulose nanocrystal (CNC-g-PAM) was first synthesized by ceric salt initiated surface graft polymerization of acrylamide onto CNC, then incorporated into chemically crosslinked poly(acrylic acid) (PAA) networks to obtain dual-crosslinked CNC-g-PAM/PAA nanocomposite hydrogels. CNC-g-PAM acted as both interfacial compatible nanofillers and physical crosslinkers through reversible hydrogen bonds between PAA and PAM on the surface of CNC. FTIR analysis confirmed the formation of above hydrogen bonds. Scanning electron microscopy observations revealed good interfacial compatibility between CNC and PAA matrix. The nanocomposite hydrogels exhibited decreasing swelling ratio with increasing CNC-g-PAM content. Uniaxial tensile tests and tensile loading-unloading tests showed that elastic modulus, breaking strength and elongation at break of the nanocomposite hydrogels were significantly increased compared to PAA hydrogel, and that the nanocomposite hydrogels exhibited good self-recovery ability after large deformation.

我们为表面改性的纤维素纳米晶体增强的机械坚韧和可自我恢复的纳米复合水凝胶的制造提供了一种简便的策略。聚丙烯酰胺接枝的纤维素纳米晶体（CNC-g-PAM）首先通过铈盐引发的丙烯酰胺在CNC上的表面接枝聚合反应合成，然后掺入化学交联的聚丙烯酸（PAA）网络中以获得双交联的CNC-g-PAM / PAA纳米复合水凝胶。CNC-g-PAM通过PAA和PAM在CNC表面之间的可逆氢键，既是界面兼容的纳米填充剂，又是物理交联剂。FTIR分析证实了上述氢键的形成。扫描电子显微镜观察表明，CNC和PAA基质之间具有良好的界面相容性。随着CNC-g-PAM含量的增加，纳米复合水凝胶的溶胀率降低。单轴拉伸试验和拉伸载荷-卸载试验表明，与PAA水凝胶相比，纳米复合水凝胶的弹性模量，断裂强度和断裂伸长率显着增加，并且纳米复合水凝胶在大变形后表现出良好的自恢复能力。