Cross-linking Polymer Mimics of Marine Mussel Adhesive Proteins
Marine biology is continually producing materials with properties unmatched by human technology. The ability of mussels and barnacles to bond strongly to wet rocks is well known, but still cannot be reproduced well with synthetic adhesives. Here, we present a family of terpolymers containing two key functionalities of mussel adhesive proteins: cationic charges and catechols. The catechol groups mimic the amino acid 3,4-dihydroxyphenylalanine (DOPA), which is important for cross-linking reactions involved in cohesive bulk curing as well as adhesive surface bonding. Focus is placed upon on the cationic nature of the adhesive proteins, the purpose of which is unknown. Terpolymers were designed to incorporate both varied amounts of cationic charges and cross-linking chemistry for adhesion. A synthesis to the target polymers is shown along with bulk adhesion measurements, both dry and underwater. When dry, the polymers adhere almost as strongly as established commercial products. When underwater, the biomimetic polymers outperform the commercial glues. Incorporation of cationic charges appears to enhance underwater polymer spreading atop the surface and promote adhesion. The adhesion strength of a neutral biomimetic polymer was also measured on a variety of surfaces. Adhesion strength was found to be quite high on metal and wood surfaces, with more modest strengths observed on poly(vinyl chloride) and Teflon. Synthetic progress and initial adhesion studies are also described for anionic catechol-containing polymers. These studies will complement the information learned from our investigation of cationic catechol-containing polymers. This dissertation yields insight towards the mechanism of marine biological adhesion and provides us with design parameters that may be used for the development of new underwater and surgical adhesives.
Wilker, Purdue University.
Polymer chemistry|Materials science
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