Bio-based coating materials were prepared from epoxidized soybean oil as a renewable source. Acetoacetylated soybean oil was synthesized by the ring-opened and transesterification reaction of epoxidized soybean oil, and its chemical structure was characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and rheometric viscosity analyses. On the basis of acetoacetylated soybean oil, several bio-based coating materials were prepared using different aromatic dicarboxaldehydes (1,2-benzenedialdehyde, 1,3-benzenedialdehyde, 1,4-phthalaldehyde, 4,4′-biphenyldicarboxaldehyde) and characterized. The resulting films possess good performance, including the highest glass transition temperature of 54 °C, a Young’s modulus of 24.91 MPa, tensile strength of 5.65 MPa, and an elongation at break of 286%. Thus, this work demonstrates the Knoevenagel condensation reaction, which is based on soybean oil as a potential newer eco-friendly raw material.
A novel plant-based
dual-cure coating system based on a Michael
addition reaction between bismaleimide (BDM) and modified acetoacetylated
castor oil was developed. The BDM has a high reactivity toward acetylacetate
groups, and the catalyst 1,4-diazabicyclo[2.2.2]octane (TEDA) was optimized by the rheological
viscosity. The gel was characterized by Fourier transform infrared
(FTIR) spectroscopy. Then, three films were prepared with the TEDA
catalyst and analyzed with solid-state
13
C NMR and FTIR
spectroscopy. The thermal and mechanical properties of the three films
were characterized by differential mechanical analysis, thermogravimetric
analysis, and differential scanning calorimetry. We found that the
cross-linking density, glass transition temperature (
T
g
), and Young’s modulus of the
coating films increased with an increase in the ratio of acetylacetate
groups from the modified acetoacetylated castor oil. This is the first
study of the reaction of BDM with plant-based acetylacetate groups.
Importantly, a quantitative ratio of acetylacetate groups can be obtained
by a thiol–ene coupling reaction and a transesterification
reaction, resulting in the formation of films having excellent performance.
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