Renewable photopolymerizable building blocks derived from soybean oil and oleic acid for protective agricultural coatings

Protective coatings have emerged as a promising approach for mitigating fruit dehiscence. In this context, photopolymerizable systems based on soybean oil and oleic acid were studied for this purpose. The synthetic route involved epoxidation followed by (meth)acrylation, resulting in four monomers: acrylated soybean oil (ASO), methacrylated soybean oil (MASO), acrylated oleic acid (AOA), and methacrylated oleic acid (MAOA). The monomer obtention was confirmed by FTIR and NMR ( 1 H and 13 C) and then submitted to an adhesion test, revealing marked differences in the adhesive ability of the synthesized monomers. ASO exhibited the highest surface adhesion, as indicated by the shortest rolling distance (7.6 cm), whereas AOA and MAOA exhibited the lowest adhesive performance, with the longest rolling distances (18.2 cm and 18.7 cm, respectively). Photopolymerization was carried out in the presence of the photoinitiators Irgacure 2959 under UV radiation, leading to the formation of stable polymer networks. The obtained polymers exhibited glass transition temperatures ranging from 4.5 °C to 36 °C and degrees of crosslinking between 61% and 71%, as well as thermal stability compatible with the formation of continuous films. The monomer derived from acrylated soybean oil was selected for a comparative study of photoinitiators, generating a poly(acrylated soybean oil) (PASO), when using Irgacure 2959 and PASO-2, with BAPO as initiator. Although PASO presented a higher degree of crosslinking, thermal analysis indicated a more heterogeneous network, whereas PASO-2 exhibited more uniform thermal behavior and greater structural homogeneity and was then applied to pods and subjected to comparative resistance tests. Coated pods showed greater resistance to applied mechanical pressure compared to the control group, indicating the potential use of the obtained polymer coating systems as functional coatings for mitigating dehiscence in agricultural crops.