Free radical seeded emulsion polymerization with participation of hydrolysis-condensation reaction(II) Parameters and modeling application
The emulsion polymerization with the simultaneous hydrolysis-condensation reaction is an important method to synthesize the organic-inorganic hybrid nanoparticles.Its process modeling and simulation is really a challenge due to the complicated reaction mechanism.In the previous paper of the authors,a model was developed based on the analysis of the process mechanism.In this paper, the kinetic model of this process was calculated to simulate this complicated process.The model was used in the seeded emulsion copolymerization system of 3-trimethoxysilyl propyl methacrylate (MPS) and styrene.The kinetics simulated by the presented model was compared with the experimental data obtained by gas chromatography (GC) and solid-state 29Si NMR along with the emulsion copolymerization process.As predicted by the model and proved by experiments, the hydrolysis could be divided into two phases characterized by the different rates.At the beginning of the reaction,hydrolysis was more active because of the part of silicone groups existing in the water phase. A greater MPS addition amount would increase the MPS concentration in the water phase and then strengthen the hydrolysis and condensation reactions.A greater surface area of latex particles would increase the hydrolysis rate because more SiOR groups could contact with water in this case.The parameter f was directly related to the surface area and decreased with more MPS content in the shell polymer.A semi-empirical equation of the parameter f was derived.