High biocontent natural plant oil based UV-curable branched oligomers

•A novel kind of soy-based UV-curable branched oligomer (ACSO) was synthesized.•Cashew nutshell liquid (CNL) was incorporated onto the backbone of epoxidized soybean oil.•The UV-cured films exhibited enhanced thermal and mechanical properties.•High biorenewable content was maintained due to the biorenewable character of cashew nutshell liquid.•The improved coating properties are attributed to the incorporated aromatic ring and multi-branched structure of oligomer.