Backbone editing of oxidized polyethylene: insertion of oxygen and nitrogen atoms via hydroxyalkyl azide-mediated rearrangements

Abstract

The properties, applications, and end-of-life considerations of plastics are fundamentally linked to the structure of the polymer backbones at the core of these materials. With that in mind, editing the polymer backbone composition offers exciting opportunities to transform the plastics economy; yet, few examples of such transformations utilize commodity plastics as starting materials. In this work, we describe the development of a tandem C–H oxidation/hydroxyalkyl azide mediated rearrangement strategy that converts polyethylene into “polyethylene-like” materials with iminium ethers, esters, amides, and other pendant chemical functionality. Control over formation of esters or amides is achieved by variation of the hydroxyalkyl azide reagent, as well as processing conditions. By targeting specific functionalities, a variety of thermal and mechanical properties can be accessed. For example, incorporation of iminium ethers decreases the Young's modulus of post-consumer PE from 196 MPa to 69–83 MPa, but conversion of the iminium ethers to esters and amides produces materials with moduli of 212–287 MPa—values higher than the original material. Thus, the demonstration of a modular backbone editing methodology for polyethylene showcases the broader value of this emerging strategy for polymer modification.