Hollow lignin azo colloids encapsulated avermectin with high anti-photolysis and controlled release performance

• Lignin azo polymer was prepared by diazotization modification of alkali lignin.
• Hollow lignin azo colloids were obtained by self-assembly in selective solvents.
• Hollow lignin colloids show remarkable encapsulation efficiency for avermectin.
• Lignin encapsulated avermectin has excellent anti-photolysis and control release performance.

Lignin-based azo polymer (AL-azo-H) was prepared from alkali lignin (AL) and then used to prepare uniform colloids via self-assembly. Due to the unique UV-blocking performance, AL-azo-H colloids were applied to encapsulate photosensitive pesticide avermectin (AVM). The self-assembled structure of AL-azo-H colloids and their controlled release and anti-photolysis performances for AVM were investigated by dynamic light scattering (DLS), static light scattering (SLS), transmission electron microscopy (TEM) and high performance liquid chromatography (HPLC). Results show that AL-azo-H colloids are hollow spheres. Hollow AL-azo-H colloidal spheres have remarkable AVM encapsulation efficiency as high as 61.49% (w/w). The cumulative release amount of AVM encapsulated by AL-azo-H (AL-azo-H@AVM) after 120 h was 84% and the release was still going on. The decomposition rate of AL-azo-H@AVM was less than 41% even after 72 h of UV irradiation. Hollow AL-azo-H colloidal spheres showed excellent UV-blocking and controlled release performance for AVM.