Opportunities and Limitations of Nanoagrochemicals

Nanoagrochemicals conceived based on safe-by-design principles could provide, besides yield increases, real benefits for the environment due to lower losses of agrochemicals to wind drift and rainwater run-off, and lower toxicity to non-target organisms. As an emerging new technology rather than ‘just another’ active ingredient, nanoagrochemicals should be evaluated and compared to conventional products using multiple criteria, including the production costs, efficiency, mode of action, degradability, and (lack of) effects on non-target organisms. Current studies on nanopesticides suggest, on average, ca. 31 % more efficiency and ca. 43 % less toxicity on non-target organisms. Observations of a 5–10-fold increase in efficiency in laboratory studies need validation in the field. The most significant challenges for nanoagrochemicals today are to produce them at competitive costs and overcome the regulatory obstacles to register products containing nanomaterials.     

Biodegradable High-Density Polyethylene-like Material

We report a novel polyester material generated from readily available biobased 1,18-octadecanedicarboxylic acid and ethylene glycol possesses a polyethylene-like solid-state structure and also tensile properties similar to high density polyethylene (HDPE). Despite its crystallinity, high melting point (T_m=96 °C) and hydrophobic nature, polyester-2,18 is subject to rapid and complete hydrolytic degradation in in vitro assays with isolated naturally occurring enzymes. Under industrial composting conditions (ISO standard 14855-1) the material is biodegraded with mineralization above 95 % within two months. Reference studies with polyester-18,18 (T_m=99 °C) reveal a strong impact of the nature of the diol repeating unit on degradation rates, possibly related to the density of ester groups in the amorphous phase. Depolymerization by methanolysis indicates suitability for closed-loop recycling.