Department of Bioengineering, University of California at San Diego, La Jolla, CA 92093, USA.
Proc Natl Acad Sci U S A. 2012 Mar 20;109(12):4383-8. doi: 10.1073/pnas.1201122109. Epub 2012 Mar 5.
Synthetic materials that are capable of autonomous healing upon damage are being developed at a rapid pace because of their many potential applications. Despite these advancements, achieving self-healing in permanently cross-linked hydrogels has remained elusive because of the presence of water and irreversible cross-links. Here, we demonstrate that permanently cross-linked hydrogels can be engineered to exhibit self-healing in an aqueous environment. We achieve this feature by arming the hydrogel network with flexible-pendant side chains carrying an optimal balance of hydrophilic and hydrophobic moieties that allows the side chains to mediate hydrogen bonds across the hydrogel interfaces with minimal steric hindrance and hydrophobic collapse. The self-healing reported here is rapid, occurring within seconds of the insertion of a crack into the hydrogel or juxtaposition of two separate hydrogel pieces. The healing is reversible and can be switched on and off via changes in pH, allowing external control over the healing process. Moreover, the hydrogels can sustain multiple cycles of healing and separation without compromising their mechanical properties and healing kinetics. Beyond revealing how secondary interactions could be harnessed to introduce new functions to chemically cross-linked polymeric systems, we also demonstrate various potential applications of such easy-to-synthesize, smart, self-healing hydrogels.
由于其众多潜在的应用，能够在受损后进行自主修复的合成材料正在快速发展。尽管取得了这些进展，但由于水的存在和不可逆的交联，永久性交联水凝胶的自修复仍然难以实现。在这里，我们证明了永久性交联水凝胶可以通过在水凝胶网络中配备带有最优亲水和疏水部分的柔性侧链来实现自修复，这使得侧链能够以最小的空间位阻和疏水塌陷来介导水凝胶界面之间的氢键。报告的自修复过程非常迅速，在水凝胶中插入裂缝或两个单独的水凝胶片并置几秒钟内即可完成。这种修复是可逆的，可以通过 pH 值的变化来开启和关闭，从而可以对外来控制修复过程。此外，水凝胶可以在不损害其机械性能和修复动力学的情况下，多次进行修复和分离。除了揭示如何利用次级相互作用为化学交联聚合物系统引入新功能外，我们还展示了这种易于合成、智能、自修复水凝胶的各种潜在应用。
