Preparation & Characterization of Resorcinol-Formaldehyde Aerogel Microparticles Using Emulsion-Gelation Method

Kurzfassung

Resorcinol-Formaldehyde (RF) aerogel is an important class of organic aerogels, which exhibits large surface area, low density and high pore volume and is also precursor for carbon aerogel. They find applications in electrodes, batteries, foundry industries, adsorbents, etc. However, since milling and grinding of monolithic aerogels to granules of specific size is nontrivial, the preparation of organic aerogels in the form of micro-particles is of great interest because of the easy fabrication, reduced process time and equipment costs, easy handling, etc. There are various methods available to prepare aerogel micro-particles such as dripping, jet-cutting, prilling by vibration, spray drying, emulsion-gelation method, and etc. In this work, RF aerogel mirco-particles were prepared by emulsion-gelation method. The aqueous RF sol was prepared by mixing appropriate quantities of resorcinol, formaldehyde, H2O and Na2CO3 with continuous stirring at room temperature. The molar ratios of R/F, R/C & R/W were maintained as 0.74, 200 & 0.044, respectively. RF sol was slowly added to the oil phase (Rapeseed oil) under stirring at 60 C in a water bath. The stirring was continued for 3h until cross-linked gel spheres were formed. Then, the suspension was kept in an oven at 60 C for curing. Further, the spheres were separated by filtration and washed several times with alcohol to exchange the water. The alcogel spheres were dried by super-critical and ambient drying methods. The dried RF particles were characterized using N2 adsorption isotherms, gas pycnometry and scanning electron microscopy. RF aerogel particles with a surface area of 284 m2/g, pore volume of 0.88 cm3/g, pore diameter of 11.09 nm and average particle diameter of 200 µm were produced. Further investigations are under progress to achieve reproducibility and scalability to the production of large quantities for foundry applications.