NSF Young Investigator

这是美国国家科学基金会授予Eric Beckman的青年研究者奖，以表彰他对聚合物工艺和/或产品的改进，以减少其对环境的不利影响。例如，他将研究双酚A聚碳酸酯的生产。目前，光气和双酚A二钠盐在界面过程中反应，然后通过高温过程产生氯化钠作为副产物。在进一步加工之前，必须从产品中消除大量残留溶剂，所产生的盐必须作为危险废物填埋。贝克曼博士计划探索一条聚碳酸酯生产路线，该路线使用超临界二氧化碳作为单体和工艺溶剂，对环境的影响较小。二氧化碳、硝基苯酚和硝基苯氧锡催化剂将结合生成碳酸硝基苯基，然后在温和的温度下反应生成高分子量的聚碳酸酯。在聚合过程中产生的硝基苯酚随后与二氧化碳一起从聚合物熔体中剥离出来，再循环到单体生产过程中。这条路线将通过(1)消除盐副产物和氯化溶剂，(2)降低聚碳酸酯生产的能量需求，(3)从聚合过程中消除光气来减少聚碳酸酯合成对环境的影响。将研究的另一个过程将涉及聚合物的合成，其中在分子水平上将改进的可回收性纳入材料。许多短寿命包装材料对环境的影响源于它们对整体固体废物问题的影响。目前的回收技术允许整个塑料废物流的一小部分被回收和再加工。任何热塑性材料，如果在使用后以相对纯净的形式保留，可以再加工从而回收，因此回收问题实际上是一个分离问题。PI计划生成含有官能团的聚合物，这些官能团虽然疏水，但在一个合成步骤中很容易可逆地转化为亲水性基团。因此，这些材料可以在化学处理后溶解在水中，既可以从双层或复合产物中提取，也可以在功能化反应逆转后回收。

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.