Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer

Abstract

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s 21. Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 mm, shell thicknesses ranging from 10 to 50 mm and shell pore diameters ranging from 1 to 10 mm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core -shell multimaterial particles.

Production of uniform droplets using membrane, microchannel and microfluidic emulsification devices

“…In order to produce core-shell drops with an ultra-thin shell (less than 100 nm), a modified device can be used with a biphasic flow in the injection capillary (Kim et al, 2011b). The shell material can be polymerised to produce monodisperse polymer shells around the inner drops (Kim et al, 2007b;Liu et al, 2010;Ye et al, 2010;Kanai et al, 2010) or a reaction can take place within the core material . Alternatively, a shell may contain dissolved amphiphilic molecules or particles which can undergo self-assembly upon solvent evaporation, leading to the generation of vesicles such as liposomes , polymersomes (Lorenceau et al, 2005; and colloidosomes .…”

Stimulus-responsive liquids for encapsulation storage and controlled release of drugs from nano-shell capsules

“…PMSQ capsules were collected in a crosslinker (distilled water) and possessed good mechanical properties and chemical durability [24]. In addition, PFH is an unreactive, immiscible and inert liquid, and does not change the composition of the shell material [23].…”

Scaling the heights—challenges in medical materials

“…The paper by Chang et al (2010) uncovers a unique electrically driven, commercially scalable processing method to prepare fine polymer shelled hollow capsules, controlling both the shell thickness and capsule diameter and they go on to indicate how the shape of the capsules can also be changed. The paper by Ye et al (2010) complements this area of research very well by reporting their research on the use of microfluidic processing to generate polymer particles and capsules, and illustrate further how the polymer material can be converted to ceramic. In their papers, Ankola et al (2010) and Schiffter et al (2010) illustrate two invaluable examples of nanoscale drug delivery.…”