Development of polyurethanes with phytoavailable boron retention capacity

Abstract

For fertilization of crops with boric acid (H3BO3), the use of material with capacity of charge (boron retention) and discharge (boron release) has potential applications in the development of fertilization systems and in the treatment of irrigation water. This study sought to obtain a composite material from polyurethanes (PUs) and N-(4-vinylbencil)-N-methyl-D-glucamine (VbNMDG) by using the technique of interpenetrating polymer networks (IPN), with potential applications in the development of boron fertilization systems. To that end, several PUs were synthesized from an isocyanate (methylendiphenyl-isocianate, MDI) and polyols with variable molecular weight (ethylene glycol, glycerol and manitol). PUs were used as a support matrix and a second network was synthesized by free radical polymerization of VbNMDG, which was previously synthesized by nucleophilic substitution between 4-vinylbenzyl chloride and N-methyl-D-glucamine. Capacity of retention and release of boron were evaluated by batch experiments and the quantification of boron concentration was estimated using azomethine-H method. Results suggest that IPNs obtained from manitol have a larger retention capacity of H3BO3 than those obtained from ethylene glycol and glycerol. Retention properties of IPNs increase as the R-OH/H3BO3 ratio increases. The study concluded that IPNs can be obtained from PUs and poli(VbNMDG) using dioxane as solvent.

Keywords

• phytoavailable boron
• interpenetrating polymer networks
• n-methyl-d-glucamine
• polyurethane