Most waterborne epoxy resin emulsifiers are inactive, and the free emulsifier will precipitate out during the curing of the coating film, which will seriously affect the water resistance, solvent resistance, and hardness of the coating film.Herein we prepared a new type of nonionic active epoxy emulsifier. First, 1,4-butanediol diglycidyl ether reacts with polyethylene glycol at a higher temperature to form an epoxy-terminated modified hydrophilic segment. Then 2,4-toluene diisocyanate link the hydrophilic segment and the epoxy resin E-31 (according the reactivity of the hydroxyl group on the epoxy resin E-31) to obtain an emulsifier for emulsifying epoxy resins. The synthesized emulsifier's cloud point is 89 C and hydrophilic-lipophilic balance is about 13.1. The most suitable condition of the phase inversion is that the emulsification temperature is 60 C and the stirring speed is 1500 r min À1 . The coating films obtained from synthesized emulsifier is dense and uniform with excellent mechanical properties.

High-performance casting polyurethane elastomers (CPUe) were successfully synthesized by the reaction of polyurethane prepolymer (PUP) blocked by methyl ethyl ketone oxime (MEKO) with diamine chain extenders. The effects of blocking agent were systematically studied on the structures, thermal stabilities, mechanical properties, and processability of polyurethane. The addition of MEKO significantly improved the tensile strength and toughness. The maximum tensile strength was 35.6 MPa, and the maximum elongation at break was 1065%. The high strength and toughness were attributed to the fact that under mild reaction conditions, the reaction tended to extend the molecular chains, which indicated that the formation of long chains was conducive to the extension and self-reinforcement of chain segments. Crystallization and strong hydrogen bonds between molecules also led to low loss factor. This deblocking polymerization strategy solves the gel problem in the polymerization process, and provides a new idea for the preparation of CPU.

Four different systems of cast polyurethane elastomers were prepared through two‐step method by adjusting different isocyanates and amine chain extenders. The blocked polyurethane prepolymer synthesized by the reaction of methyl ethyl ketoxime (MEKO) and the prepolymer weakens the reactivity with the amine chain extender. The mechanical and thermal properties of cast polyurethane prepared by different combinations were analyzed through comparison. The microphase separation of hard and soft segments structure in different systems were observed by using atomic force microscope (AFM). Through dynamic mechanical analysis (DMA), the influence of various structures on the loss factor is discussed. Studying the dynamic endogenous heat of cast polyurethane (CPU) by changing the hard segment structure provides a novel idea for the construction of polyurethane with low‐damping structure.