We report the photochemically induced molecular transformations of the poly(butylene adipate-co-terephthalate) (PBAT) polymer by quantifying the reaction rate constants (k) and yields for the primary photochemical pathways, including Norrish type I and II scission reactions, oxidation through hydroxylation of the terephthalate, and cross-linking. A suite of analytical techniques was used to quantify the reactions. Methodologies such as 1H nuclear magnetic resonance were used to identify molecular moieties that could be used as indicators for the chemical reaction pathways, with some photoinduced products (e.g., terminal aldehydes) being reported for the first time. Subsequently, doped-polymer film systems, analyzed with fluorescence spectroscopy, gas chromatography with flame ionization detection, and gas chromatography-mass spectrometry, were used to calibrate and quantify these molecular moieties upon photolysis. Ultimately, this uniquely comprehensive work culminates in quantification of the primary chemical reactions occurring in solid-state PBAT thin films. By quantifying photochemical transformations, this work will aid in predictive modeling of environmental transformations of polymers and guide the design and use of such technologies.
Bibliographical noteFunding Information:
M.A.M.-J. thanks the Joint Research Network on Advanced Materials and Systems (JONAS) program of BASF SE and ETH Zürich for scientific and financial support. M.A.M.-J. additionally thanks Kristopher McNeill and Michael Sander for their mentorship and guidance on this project. Luisa Fischer and Alvaro Olgrabek are acknowledged for their efforts in aiding in method development on the gel fraction and oxidation. E.M. thanks the Undergraduate Research Opportunity Program at UMD for funding and Brian Hinderliter for his guidance on the MatLab fitting needed for calculating cross-link density from the swelling data.
© 2021 American Chemical Society.
- chemical transformations
- environmental degradation