Influence of the monomers type on the morphology of polyamide microcapsules.

Various polyamide microcapsules were prepared via an inverse emulsion system (water in oil) by interfacial polycondensation of terephthaloyl dichloride with the aliphatic diamines ethylene diamine (EDA) and 1,6-hexane diamine (HMDA), and the aromatic diamine 1,4-phenylene diamine (PDA). Three types of polyamide microcapsules were thus obtained and labeled: CAPS EDA, CAPS HMDA, and CAPS PDA, respectively. The influence that the various substitutions had on particle size distribution, membrane microstructure, porosity and specific surface area and water content of the polyamide microcapsule was investigated. The roughness, porosity and porous volume of the polyamide membrane increased in the order: CAPS EDA < CAPS HMDA < CAPS PDA. Sodium chloride permeation experiments were performed to obtain an insight into the impact of structural changes on the permeability of the microcapsules to ionic species. The NaCl diffusion and permeability coefficients through the microcapsules were found to be in the order of 10(-8) cm2/s and 10(-5) cm/s, respectively.