Synthesis of Aromatic Polyamide-Silica Composite Particles and the Effect of Incorporating Silane Coupling Agent

Aromatic polyamide (PA)-silica (SiO2) composite particles were synthesized incorporating a silane coupling agent (SCA) at two different concentrations or without the SCA, using a mix-ture of acetone and N,N-dimethylacetamide. The three types of composite particles were macroscopically similar to the original silica particles in terms of size and morphology. The extent to which the SiO2 particles were coated with the SCA was found to be dependent on the concentration of the SCA used in the synthesis. However, all particles had almost the same level of PA coating regardless of the amount of SCA added. These coatings decreased the total pore volume and the surface area of the porous SiO2 particles while maintaining the original porous structure. Adsorption capacity tests using rhodamine B in water showed that all PA-coated particles removed 73 to 84% of the dye while untreated particles or those coated with only the SCA adsorbed from 14 to 21%. This significant difference demonstrated the beneficial effect of the PA. Thus, composite particles with significant dye adsorption efficiencies could be obtained without the SCA treatment.