Novel environment-friendly superhydrophobic bio-based polymer derived from liquefied corncob for controlled-released fertilizer

Abstract

The application of bio-based materials as coatings for fertilizers is sustainable and environmentally-friendly compared to petroleum-based materials. However, these hydrophilic bio-materials often have undesired release characteristics for controlled-release fertilizers. Superhydrophobic modified bio-based materials, mostly synthesized with nanoparticles, could be used to enhance the release characteristics, but the presence of nanoparticles usually needs more complex technology and adds to the production cost. In this work, bio-based polyurethane was synthesized from liquefied corncob to coat urea. Subsequently, polydimethylsiloxane (organosilicon-PDMS) modified bio-based polyurethane was developed to increase the hydrophobicity of the coating. Furthermore, the bio-based material was dual modified with nano-silica and organosilicon-PDMS to achieve superhydrophobicity through decreasing the surface energy and improving the nanoscale surface roughness. The dispersion and application process of nanomaterials was simplified to reduce the production cost. The release characteristics of the superhydrophobic organosilicon-PDMS and nano-silica dual modified bio-based polyurethane coated urea (SSBCU) were significantly enhanced compared to unmodified bio-based polyurethane coated urea (BCU). This is because the superhydrophobic coating reduces the number of micropores, and can prevent water from entering the inner shell. The superhydrophobic coating shows great potential for application in controlled-release fertilizers.