Controlled and Expeditious Synthesis of Epoxidized Natural Rubber and Stable Latex Modulated by Cationic Surfactants

ABSTRACT Epoxidized natural rubber (ENR), produced via the epoxidation of natural rubber (NR), has important economic value. The introduced epoxy groups significantly enhance the polarity and reactivity of the polymer matrix, granting ENR considerable potential for applications. This study chooses octadecyl trimethyl ammonium chloride (OTAC) as the surfactant in NR latex to produce ENR by in‐situ method. ENR with different epoxidation degrees (EPD) can be rapidly synthesized at higher dry rubber content (DRC) and temperature in OTAC‐stabilized latex than nonylphenol ethoxylate (OP‐10) stabilized latex. The effects of DRC of latex and temperature on the epoxidation reaction are systematically investigated. The results reveal that the OTAC‐stabilized system enables efficient epoxidation at a high DRC (50%), while exhibiting minimal ring‐opening of epoxy groups. The viscosity and Zeta potential analysis reveal the contributions to the excellent colloid stability of OTAC modified latex and superior long‐term storage stability. Dilution experiments of the ENR latex validate the exceptional stability of the OTAC‐stabilized system. Structural analysis of surfactants during the epoxidation process indicates OP‐10 underwent oxidative degradation, whereas OTAC maintained structural integrity. This study provides an efficient strategy for the stable production of ENR and ENR latex with different EPD, especially those with EPD higher than 50%.