The separation of water from crude oil has long posed a critical challenge in the oil industry, where stable water-in-oil emulsions hinder efficiency and environmental safety. Traditionally, chemical demulsifiers have been employed in this process. However, most of these demulsifiers are petroleum-based, toxic, and environmentally harmful, highlighting the need for sustainable alternatives. Castor oil maleate (COM) oligomers are suitable biobased demulsifiers for water-in-oil separation because they are biodegradable, nontoxic, and environmentally friendly, offering an option toward greener solutions in oil processing. This study synthesized COM oligomers by reacting castor oil and maleic anhydride using six distinct initiators: di-