Rapidly Responsive Smart Adhesive-Coated Micropillars Utilizing Catechol-Boronate Complexation Chemistry

AR Narkar, C Kendrick, K Bellur, T Leftwich, Z Zhang, BP Lee*
June 15, 2019
Soft Matter, 15, 5474-5482, 2019.

Smart adhesive hydrogels containing 10 mol % each of dopamine methacrylamide (DMA) and 3-acrylamido phenylboronic acid (APBA) were polymerized in situ onto polydimethylsiloxane (PMDS) micropillars with different aspect ratio (AR = 0.4 1 and 2). Using Johnson-Kendall-Roberts (JKR) contact mechanics tests, the adhesive-coated pillars demonstrated strong wet adhesion at pH 3 with work (Wadh) and strength (Sadh) of adhesion values of 420 mJ/m2 and 18 kPa, respectively. At pH 9, the formation of catechol-boronate complex significantly reduced Wadh and Sadh values (4 and 14-fold reduction, respectively). Changing pH between 3 and 9, repeatedly activated and deactivated the adhesive for adhesion. When compared to bulk adhesive hydrogel of the same composition, adhesive-coated pillar exhibited significantly faster rate of transition (1 min) between strong and weak adhesion. This was attributed to an increased surface area to volume ratio of the adhesive hydrogel-coated pillars, which permitted rapid diffusion of ions into the adhesive matrix to form or break the catechol-boronate complex.


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