Facile preparation of the novel castor oil-based benzoxazine–urethane copolymer with improved high-frequency dielectric properties

摘要: The novel star shaped benzoxazine-co-urethane prepolymers are first synthesized from the natural resource castor oil, hydroxyl terminated benzoxazine and diisocyanate through facile one-pot formulation method. Then cured copolymers can be obtained by ring-opening polymerization of oxazine groups prepared prepolymers. Both hexamethylene 4,4′-methylenediphenyl employed as aliphatic aromatic diisocyanate, respectively, to clarify their effects on chemical structure high-frequency dielectric properties copolymers. In comparison with pure polybenzoxazine, copolymer films occupy improved owing introduction three branching leading reduction molecular polarity improvement free volume. It should noted that not only decreases copolymer, but also enhances intermolecular interaction entanglement between oil for Accordingly, based poly(benzoxazine-co-urethane) occupies minimum constants (2.94, 5 GHz; 2.96, 10 GHz) relatively high glass transition temperature (220 °C). Therefore, this work provides a simple path improving benzoxazine, gives some insight into diisocyanates formation poly(benzoxazine-co-urethane)s.