(709d) Isolating Large Quantities of Liquid Crystalline Pyrene Trimer Via Continuous Supercritical Extraction

Semi-continuous, supercritical extraction (SCE) with toluene was used to fractionate polycyclic aromatic hydrocarbon (PAH) pitches into more favorable, highly concentrated materials. In particular, the starting pitch was produced by the catalytic polymerization of pure pyrene using AlCl3, or by thermal polymerization, with both being done at temperatures from 300-500 °C. The trimer of pyrene has been shown to be 100% mesophase, making it an ideal precursor for advanced carbon materials. Unfortunately, yields for the trimer are quite low, typically ranging from 5-10% of the pitch at best. Our previous work in studying the kinetics of the reaction has allowed us to optimize the conditions for producing more trimer-rich pitches, approaching 15% by weight. With this, we have also coupled our 2-stage continuous SCE technique to further concentrate the trimer in the pitch and enable us to produce large quantities of trimer-rich material that exhibit liquid crystalline properties. Concentrations of the samples were measured by GPC-RI and MALDI-ToF, and using this technique, we are able to produce up to 100’s of grams of materials in a single run. Fractions created were shown to be 50% trimer and higher, with the remaining weight being comprised of dimer or tetramer.