Lamberty Zachary D, Tran Ngon T, van Engers Christian D, Karnal Preetika, Knorr Daniel B, Frechette Joelle
Chemical and Biomolecular Engineering Department, University of California, Berkeley, Berkeley, California 94760, United States.
DEVCOM U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland 21005, United States.
ACS Appl Mater Interfaces. 2023 Jul 26;15(29):35720-35731. doi: 10.1021/acsami.3c06545. Epub 2023 Jul 14.
Multidentate hydrogen-bonding interactions are a promising strategy to improve underwater adhesion. Molecular and macroscale experiments have revealed an increase in underwater adhesion by incorporating multidentate H-bonding groups, but quantitatively relating the macroscale adhesive strength to cooperative hydrogen-bonding interactions remains challenging. Here, we investigate whether tridentate alcohol moieties incorporated in a model epoxy act cooperatively to enhance adhesion. We first demonstrate that incorporation of tridentate alcohol moieties leads to comparable adhesive strength with mica and aluminum in air and in water. We then show that the presence of tridentate groups leads to energy release rates that increase with an increase in crack velocity in air and in water, while materials lacking these groups do not display rate-dependent adhesion. We model the rate-dependent adhesion to estimate the activation energy of the interfacial bonds. Based on our data, we estimate the lifetime of these bonds to be between 2 ms and 6 s, corresponding to an equilibrium activation energy between 23 and 31. These values are consistent with tridentate hydrogen bonding, suggesting that the three alcohol groups in the Tris moiety bond cooperatively form a robust adhesive interaction underwater.
多齿氢键相互作用是提高水下附着力的一种很有前景的策略。分子和宏观尺度的实验表明，通过引入多齿氢键基团可以提高水下附着力，但要将宏观附着力强度与协同氢键相互作用定量关联起来仍然具有挑战性。在此，我们研究了模型环氧树脂中引入的三齿醇部分是否协同作用以增强附着力。我们首先证明，引入三齿醇部分会导致在空气和水中与云母和铝具有相当的附着力强度。然后我们表明，三齿基团的存在会导致能量释放速率随着空气和水中裂纹速度的增加而增加，而缺乏这些基团的材料则不显示速率依赖性附着力。我们对速率依赖性附着力进行建模以估计界面键的活化能。根据我们的数据，我们估计这些键的寿命在2毫秒到6秒之间，对应于23到31之间的平衡活化能。这些值与三齿氢键一致，表明Tris部分中的三个醇基团协同键合，在水下形成了强大的粘附相互作用。
