Encapsulation of agrichemicals by renewable cellulosic derivatives

Abstract

Cellulose derivatives, charged with fungicides, have been prepared as particles for use as a wood preservative. The particles were designed to encapsulate the current industry-standard chemical agents used to minimise wood degrading fungal action and to deter termites. A detailed study on the most effective methodology that would be suitable for scaled-up production was undertaken. The methods explored included: double emulsions, solvent diffusion by dialysis membrane and phase inversion emulsification. Particles formed by these methods were characterised by scanning electron microscopy, dynamic light scattering, nuclear magnetic resonance spectroscopy and infrared spectroscopy. The fungicide incorporation was confirmed by nuclear magnetic resonance studies and gas-chromatography analytical analysis. The phase inversion emulsion process was found to be highly effective and readily manipulated to modify particle formation. Particles were successfully prepared containing fungicides in a yield of 35-75% (method dependant), containing the biocide at approximately 50% mass of biocide to total particle mass. Thus, this process was optimised through modifying the addition time of the aqueous phase, as well as variation of the surfactant and salt concentrations. With an optimised particle forming method, three fungicides were incorporated into the formulation and subsequently analysed to demonstrate successful biocide incorporation. The biocide charged mesoparticles underwent testing for antifungal action by our industrial partners Lonza.