This is an NSF Young Investigator Award to Eric Beckman to enable him to explore modifications of polymer processes and/or products to reduce their adverse effects on the environment. For example, he will look at the production of bisphenol A polycarbonate. Presently phosgene and bisphenol A disodium salt are reacted in an interfacial process, followed by a high temperature process that yields sodium chloride as a byproduct. Large quantities of residual solvent must be eliminated from the product prior to further processing and the salt produced has to be landfilled as a hazardous waste. Dr. Beckman plans to explore a route to polycarbonate production which allows a milder environmental impact using supercritical carbon dioxide as both monomer and process solvent. Carbon dioxide, nitrophenol, and a nitrophenoxy tin catalyst will be combined to produce nitrophenyl carbonate, which is then transreacted at mild temperatures to generate high molecular weight polycarbonate. The nitrophenol produced during polymerization is then stripped from the polymer melt with carbon dioxide and recycled to the monomer production process. This route would lessen the environmental impact of the polycarbonate synthesis by (1) eliminating the salt byproduct and chlorinated solvents, (2) reducing the energy requirement for polycarbonate production and (3) eliminating phosgene from the polymerization sequence. Another process that will be studied will involve the synthesis of polymers where improved recyclability is incorporated into the material at the molecular level. The environmental impact of many short life-time packaging materials derives from their impact on the overall solid waste problem. Current recycling technology permits a small fraction of the overall plastic waste stream to be recovered and re-processed. Any thermoplastic material, if retained in a relatively pure form following use, can be reprocessed and thus recycled, therefore the recycling problem is in fact a separations problem. The PI plans to generate polymers containing functional groups, which although hydrophobic, are readily reversibly transformed to hydrophilic groups in one synthetic step. These materials could consequently be dissolved in water following chemical treatment, allowing both their extraction from bilayer or composite products, and subsequent recovery following reversal of the functionalization reaction.
