Cross Linking Between the Baffling Effect and Phase Inversion During Liquid–Liquid Monomer Mixing

Abstract

remains one of the most difficult and least understood mixing problems, in contempt of its major significance for optimization of suspension polymerization. The first step of the process, the liquid-liquid mixing and even more the medium conversion stage with increased dispersed phase viscosity and sticky polymer-monomer particles already determines the size of the final particle size distribution.Xie et al. are introducing this major challenge and give a meaningful introduction about suspension polymerization. [1] It has been widely used to produce poly-(vinyl chloride), poly-(vinylidene chloride) copolymers, polystyrene, poly-(methyl methacrylate), and high value-added polymer particulate products (e.g., chromatographic separation media, ion exchange resins, and enzyme immobilization supports). During the suspension polymerization process, a monomer (or monomers) that is immiscible or slightly soluble in water is first dispersed to form monomer droplets by stirring in the aqueous phase containing a dispersant-the liquid-liquid mixing process.Recent studies have revealed unexpected developments in drop size by only small changes in the geometrical constraints of batch vessels used for suspension polymerization. The effect of the dispersed phase fraction, surfactant concentration, as well as baffle length on the evolving drop size distribution in different low viscous liquid-liquid systems is investigated. The analysis is focused on the drop-dominated systems by hindering the coalescence by polyvinyl alcohol (PVA) concentrations up to three times higher than the critical micelle concentration. The influence of PVA on drop size in breakage-dominated systems is well reproduced with population balance equation simulations. The drops are measured using a photo-optical system with automated image analysis. The measured drop sizes increase with increasing dispersed phase fraction. As coalescence is completely hindered, all observed coalescence effects are connected to phase inversion, a catastrophic phenomenon during suspension polymerization for industrial production processes. Phase inversion can be reproduced for all studied solvents with and without the use of surfactants. In particular, the influence of the baffles can be reproduced. The system is adapted and trained to detect phase inversion as a warning system to make the suspension polymerization process more stable and robust.

Advancements in microsponges for the management of vaginal and colorectal diseases: A comprehensive review

“…It is an advantageous technique as it can be modified to one one-step or two-step process for drug loading (Figure 3). But is composed of several disadvantages as well such as the unreacted monomer also getting entrapped, leaving solvent traces behind, non-uniform structure, and monomer reaction taking a long time [31,32] . Liquid-liquid suspension polymerization is a useful approach for creating customized mucosal drug delivery systems.…”