Role of ammonium chloride in preparing poly(urea-formaldehyde) microcapsules using one-step method

This study investigates the role of ammonium chloride in the process of preparing poly (urea-formaldehyde) (PUF) microcapsules using the one-step method. Scanning electron microscopy (SEM) and optical microscopy (OM) were used to observe the morphology of the microcapsule. The results showed that the addition of ammonium chloride in the one-step process of preparing PUF resin microcapsule decreases the pH of the system. The decrease in pH of the system is due to the reaction between ammonium chloride and formaldehyde, and more so due to the reaction between ammonium chloride and hydroxymethyl urea. In addition to reducing the pH of the system, the reaction between ammonium chloride and urea-formaldehyde resin can generate surface active substances, which drives the formed UF nanoparticles to enrich the surface of the dispersed phase. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013