Abstract: Underwater adhesive are provided that include a hydrophobic polymer backbone having periodically embedded dynamic bonding units, where the underwater adhesive has nanophase separation between a first phase of the hydrophobic polymer backbone and a second phase of the dynamic bonding units. The resulting nanophase-separated morphology has clusters of dynamically bonded groups that are protected from water by a surrounding matrix of hydrophobic polymer backbone. This enables a pressure sensitive underwater adhesive with advantages of: no curing needed, reusable, recyclable, and good adhesion strength.