Robust and self-healable nanocomposite physical hydrogel facilitated by the synergy of ternary crosslinking points in a single network.
Robust and self-healable nanocomposite physical hydrogel facilitated by the synergy of ternary crosslinking points in a single network.
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DOI：
10.1039/c6tb01606e
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发表时间：
2016-09
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影响因子：
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通讯作者：
Fu-Kuan Shi;M. Zhong;Li-qin Zhang;Xiao-ying Liu;Xu-Ming Xie
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作者：
Fu-Kuan Shi;M. Zhong;Li-qin Zhang;Xiao-ying Liu;Xu-Ming Xie
将丙烯酰胺（AM）与少量的甲基丙烯酸硬脂酯（C18）疏水单体共聚接枝到乙烯基杂化二氧化硅纳米颗粒（VSNPs）表面，形成纳米刷凝胶，从而构建三元交联纳米复合物理水凝胶（TC-NCP凝胶）。TC-NCP凝胶由单个网络组成，由接枝聚合物链之间的氢键和疏水相互作用作为物理交联点，因此聚合物接枝的vsnp作为类似的共价交联点。在拉伸作用下，物理交联点依次断裂，逐渐耗散能量，然后重新组合，使网络均匀化。在拉伸过程中，接枝vsnp的聚合物链作为转移中心使应力分布均匀化。与类似共价交联点（无疏水相互作用）和氢键和疏水相互作用（无VSNPs）的水凝胶相比，三元交联点的协同作用导致TC-NCP凝胶耗散更多的能量，更有效地重新分配应力。结果表明，TC-NCP凝胶在含水量为90%时的拉伸强度为256 kPa，断裂拉伸比为28.23，韧性为1.92 MJ m-3，力学性能得到了显著改善。纯剪切试验表明，TC-NCP凝胶能够通过微裂纹从缺口尖端向整个凝胶网络发展来抵抗缺口扩展，具有1.21 × 104 J m-2的高撕裂能。网络的动态性使TC-NCP凝胶具有优异的自愈能力。结果表明，构建具有层次交联点的单凝胶网络是一种制备坚固水凝胶的通用方法。
Acrylamide (AM) and a small amount of stearyl methacrylate (C18) hydrophobic monomer copolymerize to graft on the surface of vinyl hybrid silica nanoparticles (VSNPs), forming nanobrush gelators, thereby constructing ternarily crosslinked nanocomposite physical hydrogels (TC-NCP gels). The TC-NCP gel is composed of a single network ternarily crosslinked by hydrogen bonds and hydrophobic interactions among the grafting polymer chains as physical cross-linking points and thus the polymer grafted VSNPs as analogous covalent crosslinking points. Under stretching, the physical crosslinking points successively break to gradually dissipate energy and then recombine to homogenize the network. During the stretching process, the polymer chains grafted VSNPs can homogenize the stress distribution as transferring centers. The synergy of the ternary crosslinking points leads the TC-NCP gels to dissipate more energy and redistribute the stress more effectively when compared with hydrogels dually crosslinked by both hydrogen bonds and VSNPs as analogous covalent crosslinking points (without hydrophobic interactions) and by both hydrogen bonds and hydrophobic interactions (without VSNPs). As a result, the TC-NCP gels demonstrate remarkably improved mechanical properties, including tensile strength of 256 kPa, stretch ratio at break of 28.23 and toughness of 1.92 MJ m-3 at a water content of 90%. Pure shear test shows that the TC-NCP gel is able to resist notch propagation by micro-crack development from the notch tip to the whole gel network and has a high tearing energy of 1.21 × 104 J m-2. The dynamic nature of the network endows the TC-NCP gels with excellent self-healing ability. The results evidently indicate that constructing a single gel network with hierarchical crosslinking points is a versatile method to fabricate robust hydrogels.