Hydrophobic and oleophobic surface modification using gelling agents derived from amino acids

Abstract

A series of fluorinated and non-fluorinated organogelators containing urea and amide functionalities was synthesized from readily available amino acid building blocks. These derivatives showed excellent gelation behavior in a variety of organic solvents at low concentrations ranging from 0.5–4wt%. Gelation in the presence of a fibrous substrate led to a gel-coated surface, which upon drying provided a composite with a porous microstructure morphology impregnated on the surface. The composites obtained via the impregnation of gelators provided surfaces with excellent hydrophobic properties. The superior hydrophobic behaviors observed in these composites were ascribed to a combination of increased surface roughness created by the xerogel and the presence of hydrophobic functionalities present in the gelator backbone. The composites obtained via the impregnation of gelators bearing long-chain perfluoroalkyl group on non-woven substrates also showed excellent oleophobic behavior.