Fig. 1

Synthesis and characterization of PEGS-NH2, and preparation and morphologies of the nanocomposite adhesive hydrogels. a Synthesis and molecular structure of PEGS-NH2. b 1H NMR spectra of PEGS and PEGS-NH2 in DMSO-d6. c FT-IR spectra of PEGS and PEGS-NH2 in the range of 600–4000 cm-1. d Schematic illustration of the preparation process of the double-crosslinked, nanocomposite adhesive hydrogels, including preparation of polymer precursor, in situ formation of CaP nanoparticles and formation of chemically crosslinked structure. e Macroscopic photographs and SEM images of the as-prepared hydrogels