School of Chemical Engineering, Sungkyunkwan University (SKKU), Suwon 16419, Republic of Korea.
Soft Matter. 2019 Jan 28;15(4):785-791. doi: 10.1039/c8sm02144a. Epub 2019 Jan 14.
When multiple intermolecular interactions occur simultaneously, complexed molecules undergo gelation by inter-cohesive bonding, inducing a pseudo-crosslinking effect to form a supramolecular gel. Among the number of substances that can induce supramolecular assembly, phenolic species such as 3,4-dihydroxy-l-phenylalanine (DOPA) are widely utilized for synthesizing adhesive materials. However, despite the strong adhesion capability of monomeric phenol, it lacks cohesive strength and rarely forms a supramolecular gel to secure its mechanical properties. In this study, to overcome this obstacle, we synthesized a supramolecular coacervate hydrogel by simply mixing poly(N-vinylpyrrolidone) (PVP) and tannic acid (TA), resulting in strong cohesive interactions by virtue of the larger molecular size of TA and reinforced molecular interactions attributed to the presence of galloyl groups with a high density. We further analyzed the rheological and adhesive properties of PVP-TA coacervate hydrogels, revealing that they could exhibit not only a self-healing property, but also super adhesive properties with an average adhesion strength of 3.71 MPa on a glass substrate, which is >4 times stronger than that of conventional PVP.
当多种分子间相互作用同时发生时，复合分子通过内聚键合发生凝胶化，产生伪交联效应，从而形成超分子凝胶。在能够诱导超分子组装的众多物质中，儿茶酚类物质（如 3,4-二羟基-L-苯丙氨酸（DOPA））被广泛用于合成粘性材料。然而，尽管单体儿茶酚具有很强的粘附能力，但它缺乏内聚强度，很少形成超分子凝胶来确保其机械性能。在这项研究中，为了克服这一障碍，我们通过简单混合聚乙烯吡咯烷酮（PVP）和鞣酸（TA）合成了超分子凝聚水凝胶，由于 TA 的较大分子量，形成了强大的内聚相互作用，并由于高浓度的没食子酰基存在而增强了分子间相互作用。我们进一步分析了 PVP-TA 凝聚水凝胶的流变和粘附性能，结果表明，它们不仅具有自修复性能，而且还具有超粘性，在玻璃基板上的平均粘附强度为 3.71 MPa，比传统 PVP 强 4 倍以上。
