Photo-Crosslinking, Bio-Inspired Terpolymer Adhesives Intended for Medical Applications

A bio-inspired, modular terpolymer adhesive has been synthesized containing three different functionalities: a photocrosslinking segment, wet adhesion segment, and a water soluble segment. Wet adhesion is brought on by an amino acid from mussel byssal plaques called 3,4-dihydroxyphenyl–L-alanine, which has been known to generate strong bonding under wet conditions. The photocrosslinking segment consists of an anthracene based monomer used for mechanical fortification of polymer chains. The water soluble segment consists of poly(acrylic acid), which has been known to increase water solubility of polymers and increase adhesion strength of adhesives. The terpolymer was designed to easily applicable using biologically friendly solvents including water and ethanol. Structural design was confirmed by NMR and UV-Vis spectroscopy. Reversible cycloaddition reactions were executed using a handheld UV lamp along with a photoreactor. Molecular weight increases were seen from 4.120 x 10⁴ Da to 7.429 x 10⁴ Da. Lap shear strength testing showed effects of UV exposure through increases in adhesion energy above 450%. Multiple application variables were tested to determine optimal conditions, such as solvent, concentration, and substrate. Currently, optimal conditions show a 1:1 weight ratio of polymer:solvent in water for all surfaces.