Adhesion and Surface Interactions of a Self‐Healing Polymer with Multiple Hydrogen‐Bonding Groups |
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| Authors: | Ali Faghihnejad Kathleen E Feldman Jing Yu Matthew V Tirrell Jacob N Israelachvili Craig J Hawker Edward J Kramer Hongbo Zeng |
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| Affiliation: | 1. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada;2. Materials Department, University of California, Santa Barbara, CA, USA;3. Materials Research Laboratory, University of California, Santa Barbara, CA, USA;4. Institute for Molecular Engineering, University of Chicago, Chicago, IL, USA;5. Department of Chemical Engineering, University of California, Santa Barbara, CA, USA;6. Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA |
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| Abstract: | The surface properties and self‐adhesion mechanism of self‐healing poly(butyl acrylate) (PBA) copolymers containing comonomers with 2‐ureido‐41H]‐pyrimidinone quadruple hydrogen bonding groups (UPy) are investigated using a surface forces apparatus (SFA) coupled with a top‐view optical microscope. The surface energies of PBA–UPy4.0 and PBA–UPy7.2 (with mole percentages of UPy 4.0% and 7.2%, respectively) are estimated to be 45–56 mJ m?2 under dry condition by contact angle measurements using a three probe liquid method and also by contact and adhesion mechanics tests, as compared to the reported literature value of 31–34 mJ m?2 for PBA, an increase that is attributed to the strong UPy–UPy H‐bonding interactions. The adhesion strengths of PBA–UPy polymers depend on the UPy content, contact time, temperature and humidity level. Fractured PBA–UPy films can fully recover their self‐adhesion strength to 40, 81, and 100% in 10 s, 3 h, and 50 h, respectively, under almost zero external load. The fracture patterns (i.e., viscous fingers and highly “self‐organized” parallel stripe patterns) have implications for fabricating patterned surfaces in materials science and nanotechnology. These results provide new insights into the fundamental understanding of adhesive mechanisms of multiple hydrogen‐bonding polymers and development of novel self‐healing and stimuli‐responsive materials. |
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| Keywords: | self healing polymers hydrogen bonding adhesion surface interactions surface forces apparatus |
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