Fabrication and Film‐Formation Mechanism of a Novel Antiaging Nitrocellulose‐Based Nano Waterborne Coating

ABSTRACT The traditional preparation methods for nitrocellulose (NC) emulsions have several drawbacks, such as high emulsifier content, complicated preparation processes, and the requirement for high‐energy‐consuming emulsification equipment. To address these issues, in this paper, we successfully synthesized an emulsifier‐free NC film‐forming coating using a simple, low‐energy solvent‐displacement method for the first time. Two kinds of plasticizers, epoxidized soybean oil (ESO) and dibutyl phthalate (DBP), were incorporated into the preparation process of NC. It was found that an NC‐based aqueous coating system with superior film‐forming properties could be obtained when the DBP and ESO contents reached 70% and 100% of the NC mass fraction in the system, respectively. The micromorphology, chemical structure, thermal properties, and water vapor sorption behavior of the nanocomposites were systematically investigated by field scanning electron microscopy (SEM), Fourier‐transform infrared (FTIR) spectrometer, differential scanning calorimetry, thermogravimetric analysis, and dynamic vapor sorption technology. The results demonstrated that the obtained films exhibited stable thermal decomposition, a dense and uniform structure, and low hygroscopicity (their EMC values at 90% RH were all below 1%). The accelerated aging test revealed that under the thermal shock of 50°C, the film prepared with ESO assistance showed excellent aging resistance, with its chemical structure and mass remaining essentially unchanged. In contrast, the film prepared with DBP assistance exhibited a mass decrease in the early aging stage. In addition, based on the emulsion film‐forming principle, the drying kinetics of the coating system were investigated in detail, and the influences of temperature on the drying process were investigated. We believe that this study offers valuable references for the development of eco‐friendly cellulose‐based aqueous coatings for food packaging and other applications.