A series of biobased and biodegradable copolyesters suitable for controlled release of agricultural and environmental active agents were synthesized and characterized in this work. Controlling the polymer crystallinity, hydrophobicity and surface area resulted in tailored degradation and release rates. The set of compositionally variant copolyesters were composed of 1,4-butanediol 1,6-hexamethylene diol, succinic acid and other biobased monomers, and their degradation was studied in lipase solution. The kinetics of degradation were modeled depending on the lipase concentration, crystallinity and thermal properties of the copolymers. The chemical structure, thermal properties and crystallization behaviors of these polymers were characterized using nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), respectively. Through variation of the polymer architecture, steady degradation rates up to 5 wt% per day were achieved. Techniques for loading the copolyesters with agricultural fertilizers were also explored including solution mixing, melt compounding and encapsulation. The ability of lipase-catalyzed degradation to tune the release of active compounds was quantified through phosphate assay. This work has the potential to achieve more targeted delivery of nutrients and other essential chemicals and prevent environmentally deleterious overdosing and runoff.

Biopolyesters with triggered degradation for agricultural controlled release applications

254th National Meeting (2017)

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