Poly(hydroxy urethane) adhesive based on CO2 derived cyclic carbonate

Non-isocyanate polyurethanes (NIPUs) are a promising and environmentally sustainable alternative to conventional polyurethanes (PUs). In the present study, a multifunctional cyclic carbonate was obtained from bio-based epoxy precursor via cycloaddition reaction with CO2. These cyclic carbonates were subsequently utilized in the synthesis of poly(hydroxy urethane)s (PHUs) through polyaddition reactions with a series of diamines. A systematic investigation was conducted to evaluate the influence of diamine structure, especially chain length and presence of aromatic or aliphatic units, on the physicochemical properties of the resulting PHUs, such as water uptake, glass transition temperature (Tg), elastic modulus (E-modulus), hardness, dimensional stability in water, and adhesion properties on different substrates. Furthermore, by adjusting the stoichiometric ratio between cyclic carbonate and amine functionalities, an adhesive formulation was optimized and the resulting adhesive exhibited excellent adhesion performance across various substrates, with notably high bonding strength on stainless steel, thereby highlighting the potential of NIPU-based adhesives for industrial applications.