有点标题党了。
由于PE和PP共混形成相容性不良的多相体系，所以PE和PP共混制备的材料性能并不理想。但是，来自美国科研人员近日发表在Science上的论文报道了他们在PE/i-PP增容的成果，首先使用吡啶胺Hf催化剂合成了PE-Block-i-PP的多嵌段共聚物增容剂（如下图所示），注意该嵌段共聚物一头一尾分别是PE段和i-PP段，中间段分别也是PE段和PP段交替，那么分别与纯PE和纯i-PP树脂共混时，嵌段共聚物中PE段与PE相拥抱结合，嵌段共聚物中i-PP段与i-PP树脂相拥抱结合，那么这种嵌段共聚物近似成为了可以连接PE和i-PP树脂两相的“交联剂”，是不是可以成为为一种PE和i-PP树脂共混的增溶剂呢？
作者测试了上述嵌段共聚物在PE和i-PP树脂之间的增容效果，在PE树脂片和i-PP树脂片之间压入上述PE-Block-PP嵌段共聚物然后热压成型，再测试PE片与i-PP片的玻璃强度，结果显示通过这种PE-block-i-PP多嵌段共聚物增容可以显著提升普通商业化的PE和iPP之间的粘接强度。
聚乙烯PE和全同立规聚丙烯i-PP作为最常用的两种塑料，其回收利用的量也是巨大的，由于此前两种塑料混合使用效果差，降低了回收价值，所以本文作者希望通过上述技术制备的PE-block-iPP多嵌段共聚物提升PE/iPP的共混改性性能，，提升废品回收价值。
以上介绍内容仅供参考，权威内容请阅读：
（1）研究作者视频介绍：Polymer additive could revolutionize plastics recycling | Cornell Chronicle
（2）参考文献：Combining polyethylene and polypropylene: Enhanced performance with PE/iPP multiblock polymers，Science 24 Feb 2017：Vol. 355, Issue 6327, pp. 814-816，DOI: 10.1126/science.aah5744
Abstract:Polyethylene (PE) and isotactic polypropylene (iPP) constitute nearly two-thirds of the world’s plastic. Despite their similar hydrocarbon makeup, the polymers are immiscible with one another. Thus, common grades of PE and iPP do not adhere or blend, creating challenges for recycling these materials. We synthesized PE/iPP multiblock copolymers using an isoselective alkene polymerization initiator. These polymers can weld common grades of commercial PE and iPP together, depending on the molecular weights and architecture of the block copolymers. Interfacial compatibilization of phase-separated PE and iPP with tetrablock copolymers enables morphological control, transforming brittle materials into mechanically tough blends.