Single-step Synthesis and Characterization of Core-shell Porous Silica-aromatic Polyamide Composite Particles

Abstract

Silica (SiO₂)-aromatic polyamide (APA) composite particles with a core-shell structure were synthesized in a single-step process by reacting a diacid chloride monomer with a diamine monomer in a mixture of acetone and N,N-dimethylacetamide in the presence of porous SiO₂ particles. This material was generated without any aggregation between the particles or the presence of APA agglomerates, achieved by optimizing the composition of the reaction solvent. The APA shells were estimated to have thicknesses on the order of several hundred nanometers and comprised 12 wt% of the total composite particle mass. The formation of these APA shells decreased the total pore volume and the surface area of the SiO₂ particles while maintaining the original porous structure. The pore diameters and specific surface areas of both the SiO₂ particles and the composite particles were found to vary when assessed in atmospheres composed of gaseous nitrogen, water, or toluene. These composite particles exhibited a high capacity for dye adsorption, which varied with the specific dye being adsorbed. The extent of dye adsorption was also closely related to the proportion of APA in the composite.