Figure 6.

(a) Adhesive strength of the PTFe-1 hydrogel (pH 2) to polycarbonate (PC), PMMA, nylon, glass, titanium (Ti), and SS. (b) The comparison of the adhesive strength and storage modulus of the PTFe gel in this report and various catechol-based hydrogels reported in the literature. Hydrogels include the PTFe gel prepared in this work marked as red, catechol-based chitosan hydrogels as green,⁴⁰ catechol-based chitin hydrogels as brown,³⁹ gelatin/thiourea/catechol hydrogels as purple,³¹ catechol-based 4-arm PEG hydrogels as yellow,³⁸ catechol-based protein hydrogels as gray,³⁴ and PDA–clay–PAAm hydrogels as blue.⁴¹ The graphics without outlines are attributed to the adhesiveness on tissue materials, whereas those with outlines are attributed to engineered solid materials.