Self-healable hydrogels based on the dynamically reversible boronate ester or borate ester bonds are usually prepared by reacting boronic acid or boric acid with diol compounds or polymer-like poly(vinyl alcohol) bearing a hydroxyl group in each monomer unit. Herein, we report a finding that not only facilitates the preparation but also extends the range of self-healable hydrogels of this kind. By simply copolymerizing commercially available N,N-dimethylacrylamide and 2-hydroxyethyl acrylate (8:2 weight ratio) in the presence of boric acid in a one-pot fashion, the resulting random copolymer can gel in aqueous solution at pH = 9, giving rise to a solid hydrogel (tensile strength >0.5 MPa at water content of 30%) that, on the one hand, can autonomously self-heal (near 100% fracture stress recovery within 48 h in air at room temperature) and, on the other hand, shows the characteristics of elastomer (little stress relaxation under loading and small residual deformation after unloading upon repeated 300% elongation cycles). The results reveal that it can be sufficient to have a random copolymer with comonomer units bearing hydroxyl groups for reacting with boric acid to generate dynamically reversible borate ester bonds. This finding thus points out a general, facile, and cost-effective method to obtain and explore new borate ester bond-based self-healable hydrogels.

中文翻译：

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硼酸和带有羟基的无规共聚物一锅法制备自主自愈弹性水凝胶

基于动态可逆硼酸酯或硼酸酯键的自修复水凝胶通常通过硼酸或硼酸与二醇化合物或在每个单体单元中带有羟基的聚合物状聚（乙烯醇）反应来制备。在这里，我们报告了一项发现，该发现不仅有助于制备，而且还扩展了这种自愈水凝胶的范围。通过简单地共聚市售的N , N-二甲基丙烯酰胺和丙烯酸 2-羟乙酯（重量比 8:2）在硼酸存在下以一锅方式，所得无规共聚物可以在 pH = 9 的水溶液中凝胶化，产生固体水凝胶（拉伸强度>0.5 MPa at 30% 的含水量），一方面可以自主自愈（室温下在空气中 48 h 内接近 100% 的断裂应力恢复），另一方面显示弹性体的特性（在重复 300% 的伸长循环下，加载下的应力松弛很小，卸载后的残余变形很小）。结果表明，具有带有羟基的共聚单体单元的无规共聚物足以与硼酸反应以产生动态可逆的硼酸酯键。因此，这一发现指出了一个普遍的、简单的、