Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk, Russian Federation.
Research Center for Materials Nanoarchitectonics, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
Chem Soc Rev. 2023 Jul 17;52(14):4755-4832. doi: 10.1039/d2cs00689h.
Diversification of polymer waste recycling is one of the solutions to improve the current environmental scenario. Upcycling is a promising strategy for converting polymer waste into molecular intermediates and high-value products. Although the catalytic transformations into small molecules have been actively discussed, the methods and characteristics of upcycling into new materials have not yet been addressed. Recently, the functionalisation of polymer wastes (polyethylene terephthalate bottles, polypropylene surgical masks, rubber tires, ) and their conversion into new materials with enhanced functionality have been proposed as an appealing alternative for dealing with polymer waste recycling/treatment. In this review, the term 'functional upcycling' is introduced to designate any method of post-polymerisation modification or surface functionalisation without considerable polymer chain destruction to produce a new upcycled material with added value. This review explores the functional upcycling strategy with detailed consideration of the most common polymers, , polystyrene, poly(methyl methacrylate), polyethylene, polypropylene, polyurethane, polyethylene terephthalate, polyvinyl chloride, polycarbonate, and rubber. We discuss the composition of plastic waste, reactivity, available physical/chemical agents for modification, and the interconnection between their properties and application. To date, upcycled materials have been successfully applied as adsorbents (including CO), catalysts, electrode materials for energy storage and sensing, demonstrating a high added value. Importantly, the reviewed reports indicated that the specific performance of upcycled materials is generally comparable or higher than that of similar materials prepared from virgin polymer feedstock. All these advantages promote functional upcycling as a promising diversification approach against the common postprocessing methods employed for polymer waste. Finally, to identify the limitations and suggest future scope of research for each polymer, we comparatively analysed the aspects of functional upcycling with those of chemical and mechanical recycling, considering the energy and resource costs, toxicity of the used chemicals, environmental footprint, and the value added to the product.
聚合物废物回收的多样化是改善当前环境状况的解决方案之一。升级回收是将聚合物废物转化为分子中间体和高价值产品的一种很有前途的策略。虽然已经积极讨论了将其催化转化为小分子的方法，但将其升级回收为新材料的方法和特点尚未得到解决。最近，有人提议将聚合物废物（聚对苯二甲酸乙二醇酯瓶、聚丙烯手术口罩、橡胶轮胎等）进行功能化，并将其转化为具有增强功能的新材料，作为处理聚合物废物回收/处理的一种有吸引力的替代方法。在这篇综述中，引入了“功能升级回收”一词，用于表示任何不进行大量聚合物链破坏的后聚合修饰或表面功能化方法，以生产具有附加值的新升级回收材料。本综述详细探讨了功能升级回收策略，重点考虑了最常见的聚合物，如聚苯乙烯、聚甲基丙烯酸甲酯、聚乙烯、聚丙烯、聚氨酯、聚对苯二甲酸乙二醇酯、聚氯乙烯、聚碳酸酯和橡胶。我们讨论了塑料废物的组成、反应性、可用于改性的物理/化学试剂，以及它们的性能和应用之间的相互关系。迄今为止，升级回收材料已成功应用于吸附剂（包括 CO）、催化剂、储能和传感电极材料，表现出很高的附加值。重要的是，所综述的报告表明，升级回收材料的特定性能通常与使用原始聚合物原料制备的类似材料相当或更高。所有这些优势都促使功能升级回收成为一种很有前途的多样化方法，以替代聚合物废物常用的后处理方法。最后，为了确定每种聚合物的局限性并提出未来的研究范围，我们比较了功能升级回收与化学和机械回收的各个方面，考虑了能源和资源成本、所用化学品的毒性、环境足迹以及产品附加值。
