Date of Award
2025
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Biomedical Engineering (PhD)
Administrative Home Department
Department of Biomedical Engineering
Advisor 1
Bruce P. Lee
Committee Member 1
Jingfeng Jiang
Committee Member 2
Smitha Rao Hatti
Committee Member 3
Yun Hang Hu
Abstract
Smart adhesives are materials that can reversibly gain or lose adhesion in response to external stimuli such as temperature, pH, electric fields, or light. Their switchable and temporary adhesion makes them highly promising for applications in wound healing, manufacturing, and robotic locomotion. Among them, catechol-based polymers have been widely studied for pH- and electro-responsive adhesion, due to their reversible non-covalent crosslinking. However, their performance is limited by irreversible covalent crosslinking reactions and the need for conductive surfaces in electrochemical systems. While boronic acid has been used to protect catechol, its reversibility remains limited. Therefore, new adhesive molecules and system designs are needed to achieve robust, reversible adhesion under broader conditions. This dissertation focuses on developing novel adhesive molecules and electrochemical strategies to overcome these limitations.
Project 1 introduces salicylhydroxamic acid (SHAM) as a new pH-responsive adhesive molecule. SHAM contains phenol and hydroxyl groups, allowing for π–π interactions and hydrogen bonding similar to catechol. Unlike catechol, SHAM avoids irreversible crosslinking and exhibits reversible pH sensitivity. Its work of adhesion decreased by nearly 98% at high pH and fully recovered at pH 5, demonstrating potential for simplified and reversible adhesive systems.
Project 2 explores electrochemical control of SHAM-based adhesion. Since electro-deactivation of catechol involves local pH increase near the cathode, SHAM can similarly lose adhesion via deprotonation. A 1 V charge applied for 30 seconds reduced adhesion by ~84%, which was fully restored after pH 5 treatment. This strategy achieved reversible adhesion without the need for boronic acid protection.
Project 3 addresses the challenge of requiring conductive contact surfaces. By using imidazole-TFSI modified catechol on graphene interdigitated electrodes (IDEs), current was confined within the device. Applying –3 V for 2 minutes decreased adhesion by ~81%, which was fully restored by +3 V for 2 minutes. The imidazole–TFSI coating also enhanced impedance control and protected catechol from irreversible oxidation.
In conclusion, this dissertation establishes novel strategies for designing smart adhesive systems. These findings contribute to the development of tunable, reversible adhesive systems and broaden their potential applications.
Recommended Citation
Wang, Kan, "DESIGN AND CONTROL OF REVERSIBLE ADHESION: SWITCHABLE ADHESIVE MOLECULES AND ELECTROCHEMICAL APPROACHES", Open Access Dissertation, Michigan Technological University, 2025.