通过交联可以提升塑料的性能,比如抗蠕变性能和耐热性能等,但是交联后的热固性塑料很难进行再次加工,限制了二次利用的价值,所以科研人员尝试研究可以重复加工的热固性塑料。
进展一:此前,gaofenzi.org小编此前介绍过国外科研人员通过一种交联反应,使热固性性PU塑料在加工温度下可以解交联转换成热塑性塑料,成型回到室温后又重新交联变成热固性塑料。
进展二:近期SCience报道了法国科研人员通过二氧杂硼杂环戊烷的复分解反应实现了对聚合物的交联动态转换,使聚合材料在较高温度下可以保持较好的流动性,虽然已经是交联结构。通过此方法,作者使用聚合物如聚甲基丙烯酸甲酯、聚苯乙烯和高密度聚乙烯等聚合物制备等制备的制品无色透明,具有良好的机械性能,比如表现出优异的耐溶剂性、抗蠕变性和可焊接性。另外,这种热固性塑料制品能够进行重复成型加工,制备的热固性塑料能够通过高温挤出(200 ℃)或注塑(180 ℃,15s)成型。。
High-performance vitrimers from commodity thermoplastics through dioxaborolane metathesis,Max Röttger, Trystan Domenech, Rob van der Weegen, Antoine Breuillac, Renaud Nicolaÿ*, Ludwik Leibler*,Science 07 Apr 2017:Vol. 356, Issue 6333, pp. 62-65,DOI: 10.1126/science.aah5281
Abstract
Windmills, cars, and dental restoration demand polymer materials and composites that are easy to process, assemble, and recycle while exhibiting outstanding mechanical, thermal, and chemical resistance. Vitrimers, which are polymer networks able to shuffle chemical bonds through exchange reactions, could address these demands if they were prepared from existing plastics and processed with fast production rates and current equipment. We report the metathesis of dioxaborolanes, which is rapid and thermally robust, and use it to prepare vitrimers from polymers as different as poly(methyl methacrylate), polystyrene, and high-density polyethylene that, although permanently cross-linked, can be processed multiple times by means of extrusion or injection molding. They show superior chemical resistance and dimensional stability and can be efficiently assembled. The strategy is applicable to polymers with backbones made of carbon-carbon single bonds.