This study describes the design, synthesis and spectral behavior of underwater adhesive materials which adhere to surfaces without any external force. The materials with wet adhesive properties have a wide application field from biomedical implantation and covering to antifouling materials. Mussel’s stickiness to rocks, ships, etc. inspite of strong waves in the sea inspires us to synthesize adhesives materials. Mussels attach to solid surfaces strongly using their threads and plaques. The complex fluid (mussel foot proteins, Mfps) secreted from mussels is solidified in the sea water and forms threads, each equipped with a distal adhesive plaque. Mfps have large amount of L-3,4-dihydroxyphenylalanine (DOPA) amino acid and this amino acid is responsible for adhesion of mussels to underwater surfaces. The presence of stable hydration layers around both the adhesive materials and surface results in strong hydration repulsive forces that undermine adhesion. So far, applied external forces were used to break through or disrupt the hydration layers which prevent adhesion. In this research branched PEG based polymers were modified with different amounts of DOPA in order to obtain underwater adhesive material. Their adhesive properties to spin labeled (SL) nanoparticles were tested without applying an external force by electron spin resonance (ESR) spectroscopy. As model surfaces we synthesized hydrophobic SL-polystyrene and hydrophilic SL-silica nanoparticles. ESR results showed that four arm DOPA modified PEG is able to adhere to SL-polystyrene but not to SL-silica. Moreover, adhesions of the polymers were tested by making hydrogels using iodate (IO3-) and iron (III) (Fe3+) ions. ESR results showed that hydrogels prepared from four arm DOPA modified PEG/IO3- mixture has better adhesive property to SL-polystyrene compare to hydrogels prepared from four arm DOPA modified PEG/Fe3+ mixture and adhesion of IO3- based gel form is better compared to molecule form.