Rationally designing renewable plant oil-based polymers as efficient nanocarriers for sustained pesticide delivery

Nanopesticides, which have great potential to revolutionize modern agriculture present the major forms of nanocarriers and loaded active ingredients (AIs) such as insecticides, fungicides or herbicides. Conventional petroleum-based polymers as nanocarriers with poor degradability have the potential detriment to human health and the environment. In contrast, efficient nanocarriers from renewable biomass could not only decrease the consumption of limited fossil resources, but also reduce the environmental concerns. However, the fabrication of highly efficient biomass-based nanocarriers for nanopesticides has rarely been explored owing to the limited functional groups and poor structural variations of biomass. In this work, we have reported four distinct amphiphilic renewable plant oil-based copolymers with the same chemical compositions and significantly different bottlebrush or linear molecular structures. They all have the renewable plant oil-based monomer as the hydrophobic block and easily available and degradable poly (ethylene glycol) (PEG) as the hydrophilic block. These amphiphilic copolymers, including ABA and BAB-type bottlebrush copolymers, and AB and ABA-type linear copolymers are excellent carriers, which all form well-defined spherical nanostructures of similar sizes. Among all nanopesticides with different nanocarriers and azoxystrobin, a bottlebrush copolymer with two hydrophobic domains at both ends and a diblock linear copolymer present a high pesticide-loading capacity. Further study on release and antifungal behaviors shows that the bottlebrush copolymer with two hydrophobic domains is a superior nanocarrier with long sustained release efficacy and exhibits outstanding bioactivity. This work presents a novel and sustainable approach to fabricating highly efficient nanopesticides by elegantly designing molecular structures of biomass-based nanocarriers.