Instant and Strong Underwater UV-Curable Adhesives with Bottlebrush Polyethers and Polyacrylic Acid Complex

Photo adhesives are widely used in various industries due to their high adhesion strength, fast curing and ease of use. However, manufacturing photo adhesives with underwater adhesion is a significant challenge mainly because water molecules can dissolve or swell the adhesive during in situ coacervation, and the hydration layer on the surface of the substrate prevents molecular interactions between the adhesive and the substrate. Herein, an underwater UV-curable adhesive with high adhesion strength and ultrafast curing time is composed of bottlebrush polyethers (BBPs) and poly(acrylic acid) (PAA) complex (BBPs-PAA). The BBPs component not only removes the hydration layer and prevents water intrusion into the adhesive through hydrophobic effect but also enhances adhesion and cohesion strength through hydrogen bonding. The prepared UV-curable adhesives, BBPs-PAA, can be ultrafast cured (10 s) on the surface of the substrate under UV irradiation, exhibiting ultrahigh adhesion strength on glass substrates, both in the air (14.9 MPa) and underwater (13.2 MPa). In particular, the adhesion strength of BBPs-PAA on glass substrates remains above 6.5 MPa after 30 days of immersion in water, salt, acid, and alkali solution environments. This study outlines a viable strategy for developing an instant and strong underwater adhesive, showcasing its substantial potential for diverse applications in aqueous environments.