Polyurethane/polyhydroxyurethane hybrid polymers and their applications as adhesive bonding agents

A polyurethane/polyhydroxyurethane (PU/PHU) hybrid polymer was synthesized by reaction of a cyclic-carbonate-terminated prepolymer with triethylenetetramine without employing isocyanates in the final curing step. This cured elastomer contains traditional urethane linkages from the initial prepolymer reaction as well as hydroxyurethane linkages from the final chain extension reaction. The PU/PHU hybrid exhibits microphase separation as made apparent by the presence of two glass transitions and elastomeric properties with Young's modulus of 37 MPa and strain at break of 350%. Most importantly, the PU/PHU hybrid polymer exhibits adhesion to polyimide, poly(vinyl chloride) (PVC), and aluminum substrates that is similar to or enhanced relative to those of polyurethane controls and literature values for typical polyurethane adhesives. In particular, the PU/PHU hybrid has T-peel forces of 7.8, 10.5, and 3.4 N/mm on polyimide, PVC, and aluminum, respectively, and undergoes predominantly cohesive failure rather than adhesive failure. The application of this material as a model consumer-applied adhesive for potential replacement of isocyanate-based polyurethanes is also briefly discussed.