593. Multivalent non-covalent interactions lead to strongest polymer adhesion
M. Lallemang, L. Yu, W. Cai, K. Rischka, A. Hartwig, R. Haag, T. Hugel, B. N. Balzer – 2022
Multivalent interactions play a leading role in biological processes such as the inhibition of inflammation or virus internalization. The multivalent interactions show enhanced strength and better selectivity compared to monovalent interactions, but they are much less understood due to their complexity. Here, we quantify the multivalent bond strength formed by azide, alkyne, quinone and amine groups in a polymer layer on a solid substrate. We detect molecular interactions in the range of a few piconewton to several nanonewton and can correlate them with the formation and subsequent breaking of one or several physical and chemical bonds and assign these bonds. This became possible by combining atomic force microcopy (AFM)-based single molecule force spectroscopy with covalent AFM cantilever tip attachment schemes. Surprisingly, we find that physical bonds of intermediate strength, like coordination bonds, give the highest multivalent bond strength, even outperforming chemical (covalent) bonds. At the same time, chemical bonds enhance the polymer layer density, increasing in particular the number of physical bonds formed. In summary, we can show that the key for the design of stable and durable polymer coatings is to provide a variety of multivalent interactions and to keep the number of strong physical interactions at a high level.