Porous polymer beads are spherical polymer particles with an interconnected or close cellular structure. They can be used in a wide range of applications such as separation science, ion-exchange resins, scavengers, adsorbents, blood plasma detoxification or supports for enzymes to catalyst immobilization. Furthermore, porous polymer beads can be used in self-healing composite materials to contain the healing agent. However this requires the hermetic encapsulation of the healing agent for a certain period of time as the encapsulated material has to be released only when the composite fails e.g. as a result of an accident.<br/>The production of porous polymer beads using a combination of multiple emulsions and a microfluidic set-up is one of the most typical approaches but is limited because of the low production rate and often clogging.<br/>In our work, we developed a macrofluidic co-flow method to produce filled polymer beads with an improved production rate. A high internal phase emulsions (HIPEs) with methyl methacrylate, poly(ethylene glycol) dimethacrylate and the photoinitiator Darocure 1173 in the continuous phase and HCl solution as internal phase was used. Individual drops of the HIPE are injected into a re-circulating carrier phase, which runs through a quartz glass pipe, where the continuous phase of the emulsions was UV polymerised. By controlling the injection speed and carrier phase speed, macroporous polymer beads with a pore size range from 300 to 3000 microns were produced. Furthermore, the macroporous polymer beads possessed a protective closed celled skin at the surface but an interconnected internal pore structure. Hydrochloric acid, used as a standard molecule, was encapsulated in the beads. After 24 hours exposure of the beads in air at room temperature, 60% HCl remained in the beads, suggesting the efficient encapsulating of the close-skin beads. Therefore, it is expected to employ the macroporous beads as encapsulators for self-healing agents.

Micro vs. macrofluidics. Encapsulation of hydrochloric acid in porous polymer beads

250th National Meeting (2015)

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