Sustainable cardanol-based ionic surfactants

Alkylbenzenes are among the carbon chains most commonly used as a hydrophobic part to develop surfactants.In this paper, the authors present a sustainable alternative using cardanol.Cardanol is obtained by vacuum distillation of cashew nut shell liquid which is a non-edible oil directly extracted from the shell of the cashew nut, the fruit of the cashew tree.Three ionic surfactants based on cardanol were synthesized: a cationic, an anionic and a zwitterionic surfactant.An intermediate was first synthesized by nucleophilic substitution to generate a primary amine.Subsequently, this amine was used to open the cycles of trimethylammoniumglycidyl chloride and 1,3-propanesultone to obtain cationic and anionic surfactants, respectively.And, finally, the obtained cationic and anionic surfactants were coupled with 1,3propanesultone and trimethylammoniumglycidyl chloride, respectively, to give sulfobetaine surfactants.The surface activity and Krafft temperature were studied as a function of the salt concentration of the synthesized molecules.