Preparation of monodisperse mesoporous carbon microspheres from poly(furfuryl alcohol)-silica composite microspheres produced in a microfluidic device

Uniform-sized carbon microspheres with diameters of several hundreds of microns and adjustable mesopore structure were obtained from poly(furfuryl alcohol)-silica (PFA-SiO₂) microspheres. The PFA-SiO₂ composite microspheres were synthesized via the phase transfer of FA and the subsequent polymerization in aqueous silica sol droplets formed in a simple microfluidic device, followed by carbonization and HF etching to remove the silica template. It was found that the resultant carbon microspheres were mesoporous, and their mesoporosity depended on the flow rate of the oil phase and the residence time of the microdroplet in the device during the preparation of PFA-SiO₂ microspheres. The carbon microspheres exhibited heterogeneous structure with submicron-sized ball-like carbon particles embedded in the smooth carbon matrix. The highest mesoporous volume and mesoporosity of carbon microspheres reached 1.10 cm³ g^-1 and 85%, respectively, and the mesopores were in the range of 2-20 nm. Mesoporous silica microspheres embedded with submicron-sized cavities could also be prepared by burning-off the carbon in the carbon-SiO₂ microspheres.