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Published on: July 23, 2016
Aqua-Oxidation of Polyethylene Into Carboxylic Acids Under Mild Conditions: A Catalyst-Free Upcycling Strategy for
Yinlong Chang1,2, Weiqiang Gao1,2, Sen Wang1,2
1State Key Laboratory of Chemical Engineering, College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, Zhejiang, P. R. China.
Abstract:
Noncatalytic polyolefin upcycling offers distinct advantages in eliminating catalyst costs and enhancing operational stability, yet it remains highly challenging under mild conditions. Herein, we develop an aqua-oxidation strategy that converts polyethylene into carboxylic acids at 160°C without using any catalysts or organic solvents. The mass yield of carboxylic acid is up to 97.8 wt%, of which 72.1% is comprised by C4-C10 dicarboxylic acids. The roles of H2O and O2 play in aqua-oxidation were further investigated in an in situ liquid-phase spectroscopic reactor filled with isotope-labeled D2O. It reveals that O2 governs the effective initiation and oxidation of polyethylene. Whereas H2O serves as a key medium to intensify oxygen-polyethylene interaction uniformly and inhibit localized oxidation, promoting selective upcycling to narrow-distributed acids. Moreover, this strategy allows for upcycling diverse commercial polyolefins with additives. This study presents a breakthrough in the noncatalytic upcycling of polyolefins under mild conditions and demonstrates the potential of this eco-friendly and streamlined strategy for advancing plastic circularity.
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