Preparation of mussel-inspired biopolyester adhesive and comparative study of effects of meta- or para-hydroxyphenylpropionic acid segments on their properties.

Abstract Simple and bulk preparation of catecholic polymers is challenging. Herein, we describe a novel bio-copolyester poly(DHHCA- co -4HPPA) (polyHH4P) prepared via thermal polycondensation of renewable resources 3,4-dihydroxyhydrocinnamic acid (DHHCA) and 3-(4-hydroxyphenyl) propanoic acid (4HPPA) in one pot. PolyHH4P exhibited strong adhesion properties on diverse materials, and its adhesive strength was highly dependent on the DHHCA composition (C DHHCA). PolyHH4P with 25% C DHHCA showed the highest shear strength at fracture, with values of 10.3 MPa on carbon, 9.6 MPa on glass, and 6.2 MPa on steel substrates, and these values are higher than the corresponding values for commercial instant super glue. Furthermore, the structural effects of para -hydroxyphenylpropionic acid (para -HPPA) and meta -hydroxyphenylpropionic acid (meta -HPPA) moieties on the properties of the prepared polymers were studied. PolyHH4P with the para -HPPA moiety showed an evidently improved glass transition temperature (T g s) relative to that of polyHH3P with meta- HPPA at the same C DHHCA , such as 19 °C increase at 25 mol% C DHHCA. However, unexpectedly, polyHH4P showed weaker adhesive shear strength than polyHH3P at the same C DHHCA mol%. We discussed the effects of C DHHCA , degree of crystallinity (CD), degree of branching (BD), catechol groups, and polymer chain rigidity on their properties. The difference in the adhesive strength of polyHH4P and polyHH3P can probably be ascribed to the higher symmetry and poorer flexibility in polyHH4P. The polyHH4P with an introduced rigid moiety and characterized by strong adhesion and an appropriately improved T g s is expected to have potential applications in various medical fields, for example, as a dental adhesive. Graphical abstract Image 1 Highlights • Mussel-inspired novel bio-copolyesters were prepared by a thermal polycondensation of renewable resources monomers. • Bio-copolyesters exhibited strong adhesion properties on a wide range of materials. • Adhesive strength of these copolymers was greatly related with C DHHCA. • Effects of meta - or para -hydroxyphenylpropionic acid segments on their properties were studied. • Copolymers with meta -HPPA show improved T g s but lower adhesive strength than those with para -HPPA segments. [ABSTRACT FROM AUTHOR]