Preparation of aromatic polyamide nanoparticles with multiple functional groups in mixed solvent solutions via a one-step precipitation polymerization

Abstract

Aromatic polyamide nanoparticles with carbonyl chloride (COCl) and carboxyl (COOH) groups are prepared in a one-step precipitation polymerization process using a diamine and a diacid chloride, employing a combination of various solvents. The morphology, number of COCl groups introduced and molecular weight of the resulting particles are found to be greatly affected by the composition of the reaction solution. Pyridine acts primarily as a catalyst and also reduces the particle size and affects the incorporation of COCl groups. These groups originates from the diacid chloride and are present at the ends of polymeric chains. The solubility of the particles in the reaction solution is closely correlated with the time required for precipitation and significantly influences the particle formation mechanism. This in turn affects the molecular weight and the number of COCl groups.