Organocatalytic C-H fluoroalkylation of commodity polymers

• Published in: Polymer chemistry Vol. 11; no. 3; pp. 4914 - 4919
• Main Authors: Lewis, Sally E, Wilhelmy, Bradley E, Leibfarth, Frank A
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 14.08.2020
• Subjects: Addition polymerization; Aromatic compounds; Identification methods; Material properties; Molecular weight distribution; Perfluoroalkyl & polyfluoroalkyl substances; Photoredox catalysis; Polymer chemistry; Polymers; Reactivity; Selectivity; Substrates
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/c9py01884k

Post-polymerization modification of commodity plastics diversifies their material properties and expands their potential applications. The thermal and chemical stability of polymers that contain aromatic rings, which represent a high-volume class of materials, makes it challenging to add functionality while retaining the molar mass ( M n ) and molecular weight distribution (MWD) of the original polymer. Herein, we present a metal-free C-H fluoroalkylation strategy that takes advantage of the innate reactivity of aromatic polymers. A systematic evaluation of organic photoredox catalysts for polymer C-H fluoroalkylation led to the identification of 5,10-di(2-naphthyl)-5,10-dihydrophenazine as a scaffold that balanced efficient reactivity with excellent selectivity, enabling the addition of trifluoromethyl groups onto aromatic polymers without altering the M n or MWD of the material. The metal-free functionalization method was also amenable to a range of perfluoroalkyl groups and polymer substrates, including post-consumer and post-industrial plastic waste. The methods developed and structure-reactivity relationships identified in this study will prove valuable for the continued adoption of C-H functionalization methodologies that enhance the properties of commercially available polymers. Organocatalytic post-polymerization modification of commodity aromatic polymers diversifies their material properties.