A high-stable soybean-oil-based epoxy acrylate emulsion stabilized by silanized nanocrystalline cellulose as a sustainable paper coating for enhanced water vapor barrier

Soybean-oil-based polymer is a promising bio-based water barrier coating on paper packaging but the application is challenged due to its poor water dispersibility. In this present study, 3aminopropyltriethoxysilane (APTES) modified nanocrystalline cellulose (NCC) was used to implement a stable dispersion of acrylated epoxidized soybean oil (AESO) in water and thus synergistically improved the water vapor barrier properties after coating on paper. APTES-NCC was successfully prepared, and displayed a better interface compatibility with AESO through the Michael addition reaction. Compared with NCC, APTES-NCC displayed an improved hydrophobicity and wettability with AESO, with an increase of contact angle from 38.0 degrees to 76.4 degrees, and a decrease of interfacial tension from 91.5 +/- 3.5 mN/m to 82.9 +/- 1. 8 mN/m. As an emulsifier, APTES-NCC can be more effectively adsorbed on the oil-water interface to form a more stable emulsion than NCC, with a decrease of AESO droplets size from 4.8 mm to 3.1 mm, and a remarkable improvement in static and centrifugal stability. In rheological measurement, the APTESNCC/AESO emulsion showed a wider linear viscoelastic region (3.4%), better viscoelasticity and thermal curing properties than that of NCC/AESO emulsion, which further explained that the stability of APTESNCC/AESO emulsion were improved. Therefore, APTES-NCC/AESO emulsion as a coating on paper cured into a continuous barrier film can effectively improve the water vapor barrier properties of paper, and the water vapor transmission rate (WVTR) of paper can be reduced from 1392.8 g/m2.24 h (NCC/AESO emulsion-coated) to 1286.3 g/m2 24 h (APTES-NCC/AESO emulsion-coated), both are significantly lower than that of base paper (1926.7 g/m2.24 h). CLSM testing showed that APTES-NCC could interact effectively with AESO to forming a tight barrier on paper surface and at the same time, sealing the pores inside the paper to resist water vapor penetration. The high-stable AESO emulsion prepared by APTES-NCC is expected to facilitate the utilization of NCC and AESO as a value-added material in making sustainable barrier packaging. (c) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study successfully achieved a stable dispersion of acrylated epoxidized soybean oil (AESO) in water by using 3-aminopropyltriethoxysilane (APTES) modified nanocrystalline cellulose (NCC), which synergistically improved the water vapor barrier properties of paper after coating. APTES-NCC exhibited better interface compatibility with AESO, improved hydrophobicity and wettability, and acted as an effective emulsifier. The resulting APTES-NCC/AESO emulsion coated on paper reduced the water vapor transmission rate (WVTR) significantly.