Operando Ultrafast Damage-free Diffraction-Enhanced X-ray Absorption Spectroscopy for Chemical Reactivity of Polymer in Solvents

TL;DR

This paper introduces a novel Diffraction-Enhanced X-ray Absorption Spectroscopy (DE-XAS) technique that significantly reduces radiation damage, enabling in-situ, fast, and damage-free analysis of polymer deconstruction processes in solvents.

Contribution

The paper presents a new DE-XAS method that minimizes beam damage and allows real-time chemical reactivity studies of polymers during decomposition.

Findings

DE-XAS reduces radiation damage by orders of magnitude.

Successful in-situ characterization of polymer deconstruction.

Potential for studying fast chemical reactions with high temporal resolution.

Abstract

Chemical recycling of plastics to its constituent monomers is a promising solution to develop a sustainable circular plastic economy. An in-situ X-ray absorption spectra (XAS) characterization is an important way to understand the deconstruction process. However, radiation damage, and long acquisition time, prevent such characterization for fast chemical process. Here, we present a novel experimental technique, which we name Diffraction-Enhanced X-ray Absorption Spectroscopy (DE-XAS), where the plastic material is supported on a graphene layer covering a periodic pattern of holes in a perforated SiNx membrane. The XAS is obtained by measuring the energy-dependent intensity of the X-ray diffracted beams going through the plastic film over the holes in the SiNx membrane. Our method decreases beam damage by orders of magnitude while providing good signal/noise ratio data. We demonstrate the suppression of beam damage with samples of polymethyl methacrylate (PMMA) and the operando characterization of polymer deconstruction process in acid with polydiketoenamine (PDK). This proof-of-concept of the DE-XAS technique shows its great potential for studying fast chemical processes, picoseconds to nanoseconds, using fast CCD detectors with short readout time. We believe the DE-XAS technique offers opportunities for studies of chemical reactions, e.g., photoresist, and many others.