Preparation and evaluation of organosilica nanocapsules encapsulating DCOIT by using the response surface optimization

Abstract Antifouling agent 4, 5‐ d ichloro‐2‐ n ‐octyl‐4‐isothiazolin‐3‐one (DCOIT) in a one‐stage process based on the self‐catalytic reaction between methyl trimethoxysilane (MTMS) and 3‐aminopropyl trimethoxysilane (APS) in an aqueous system without any surfactants and catalysts have been developed. The optimal preparation process parameters of organosilica nanocapsules encapsulating DCOIT (DCOIT@SiNC) were determined using response surface methodology (RSM) based on the single‐factor experimental results. The results of RSM optimization showed that 49.51% encapsulation efficiency (EE [%]) would be achieved with a shell–core mass ratio of 5.59:1, a MTMS‐APS mole ratio of 1.52:1, and a reaction temperature of 31°C. DCOIT@SiNC prepared according to the RSM optimal process exhibited a decent uniform sphericity with an average particle diameter of 660.50 nm. The encapsulation was characterized by Fourier‐transform infrared and X‐ray diffraction. The loading efficiency and thermal stability were verified via thermogravimetric analysis. Compared to DCOIT, DCOIT@SiNC had better controlled release performance, and the release kinetics investigated by Riger‐peppas model indicated that the release of DCOIT was diffusion‐controlled.