Amphiphilic Thermoresponsive Poly(Hydroxyaminoethers) as Effective Emulsifiers for Preparation of Waterborne Epoxy Resins

Amphiphilic poly(hydroxyaminoethers) (PHAEs) with thermoresponsive solubility in aqueous solutions are developed in this study. Through the control of stoichiometric ratios of functional groups and the reaction temperature, a series of PHAEs with different hydrophilic segments is synthesized, as evidenced by proton nuclear magnetic resonance (1H-NMR) and Fourier transform infrared (FT-IR) spectroscopy. These PHAEs could be dissolved in aqueous solutions and exhibit the thermal phase transitions with lower critical solution temperatures (LCSTs) due to the hydrogen bonding between the hydrophilic segments and water, as confirmed by differential scanning calorimetry (DSC). In addition, the hydrophilic-lipophilic balance (HLB) values suggest that the PHAEs are more hydrophilic amphiphiles and suitable for use as oil-in-water emulsifiers. Consequently, commercially available epoxy resins can be successfully stabilized by the PHAEs in water to form stable emulsions. These crosslinkable waterborne epoxy resins show good thermal and resistance properties, and the feasibility in anticorrosion coating applications for steel surfaces is demonstrated.