Biodegradable polymer‐metal‐organic framework (MOF) composites for controlled and sustainable pesticide delivery

Abstract

Due to high surface area, loading capacity, and selectivity, Metal-Organic Frameworks (MOFs) have shown much promise recently for potential applications in extraction and delivery of agrochemicals for environmental remediation and sustainable release, respectively. However, application of MOFs for pesticide delivery in wider agricultural context can be restricted by their granular form. Herein, an alternative approach is studied using biodegradable polymer-MOF composites to address this limitation. The loading and release of a widely used pesticide, 2,4-dichloropheoxycetic acid (2,4-D), is studied using two MOFs, UiO-66 and UiO-66-NH2, and the 2,4-D-loaded MOFs are incorporated into biodegradable polycaprolactone composites for convenient handling and minimizing runoff. The MOFs are loaded by in-situ, and post-synthetic methods, and characterised thoroughly to ensure successful synthesis and loading of 2,4-D. The pesticide release studies are performed on the MOFs and composites in distilled water, and analysed using UV-Vis spectroscopy, demonstrating sustained-release of 2,4-D over 16 days. The loaded MOF samples show high loading capacity, with up to 45 wt% for the in-situ loaded UiO-66. Release kinetics show more sustained release of 2,4-D from UiO-66-NH2 compared to UiO-66, which can be due to supramolecular interactions between the NH2 group of UiO-66-NH2 and 2,4-D. This is further supported by computational studies.