Adhesion of Catechol-Functionalized Linear-Dendritic Block Copolymers: Dendritic Effect, Self-Assembly, and Bioadhesion

Inspired by mussels protein adhesives, two series of catechol-functionalized Linear-Dendritic Block Copolymer (LDBC) adhesives are synthesized. They show lap shear adhesion strength as high as 7 MPa on aluminum substrates and adhesion up to 3 kPa on porcine skin. These water-soluble LDBCs are composed of i) either poly(ethylene glycol) (PEG) or poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) triblock copolymer (Pluronic F-127) as linear polymers, ii) Bis-MPA dendrons of generation 0, 1, and 2 as dendritic parts, and iii) 2, 4, or 8 terminal catechol moieties. A LDBCs generation comparative test on aluminum reveals a clear dendritic effect: the LDBCs of second generation display higher adhesion than the LDBCs of first generation that also display higher adhesion than the LDBCs of generation 0 for both series, assessing thus a positive dendritic effect in adhesion. Second, a comparative study is carried out between the LDBCs based on PEG and the ones based on Pluronic. The ability of the Pluronic LDBCs to self-assemble in water appears to reduce adhesion when applied on aluminum whereas it is essential to obtain adhesion on porcine skin, thanks to the formation of hydrogels, as observed by the vial inversion technique and electron microscopy.