Controlled release of urea from poly(butylene adipate-co-terephthalate) nanoparticles Available to Purchase

Rapid dissolution, volatilisation and leaching of fertilisers has been a major concern in agriculture industry. Controlled-release fertilisers help to regulate the nutrient release and reduce the environmental damage. In the present study, poly(butylene adipate-co-terephthalate) (PBAT)-based nanoparticles were synthesised for the controlled delivery of urea. Formulations with different urea to PBAT weight ratios (1:5, 1:10 and 1:15) were prepared using solvent evaporation method and characterised for morphology, crystallinity and release kinetics. X-ray diffraction analysis showed the absence of additional peaks of urea, suggesting that urea remained dispersed within the PBAT network. Scanning electron microscopy images displayed changes from rough and agglomerated surfaces in samples with lower polymer content to compact and uniform surfaces for higher PBAT compositions, thereby indicating enhanced distribution and encapsulation of urea in the polymer matrix. Zero-order, first-order, Higuchi and Korsmeyer–Peppas models were used to study urea release kinetics. The analysis showed a transition from Fickian diffusion to anomalous transport and again to Fickian diffusion with increasing polymer content, suggesting molecular diffusion and polymer relaxation. The results highlight the role of polymer composition in controlling the nutrient release behaviour and the potential of PBAT-based systems as biodegradable controlled-release fertilisers for sustainable agricultural systems.