Hydrophobic Coating of Vegetable-Tanned Leather with Dodecylamine

Vegetable-tanned leather exhibits a hydrophilic character due to the abundance of hydroxyl groups (-OH). In this study, the surface of vegetable-tanned leather was modified to become hydrophobic. The leather was coated using dodecylamine (DDA) through the padding method in the finishing process. The concentration of DDA varied from 1%, 2%, 3%, and 4% to identify the optimum concentration. The coating process was assisted by an activator, either acid or base, to improve the adhesion of DDA to leather. Uncoated vegetable-tanned leather was used as a control. The success of coating was identified using FT-IR and SEM-EDX analysis. The hydrophobicity of leather was conducted through a water resistance test. The success of coating is shown by the increase in their weight and thickness. Absorption bands of alkyl and amino groups of DDA are observed in FT-IR spectra around 1450 cm-1 and 3400 cm-1, respectively. SEM micrographs show that coated leathers have flatter surfaces as a consequence of DDA attachment on the leather surface. The water resistance test proves that the use of DDA can improve the leather hydrophobicity and enhance the water absorption time by up to 4 times. The optimum water absorption time is obtained when using 2% DDA.