Issue 13, 2023

Regioselective photocycloaddition for light-stabilised dynamic materials design

Abstract

The exact molecular network connectivity in dynamic polymer networks greatly impacts material properties and reprocessing conditions. While endo/exo stereoisomer effects of thermoreversible cycloaddition reactions (e.g. furan/maleimide) are well known to influence the overall decrosslinking kinetics of dynamic polymer networks, the impact of regioisomerism is often overlooked. Herein, we highlight the importance of interchanging regioisomer fractions in light-stabilised dynamic materials (LSDMs). Specifically, the photo-driven [4 + 2] cycloaddition of substituted naphthalenes with triazolinediones (TADs) is demonstrated to continuously equilibrate under green light, resulting in an enrichment in one of two regioisomers and effectively changing the overall cycloreversion kinetics. To bypass implications of this chemically inhomogeneous nature of the crosslinks when embedded in a macromolecular gel, a library of naphthalene reaction partners is screened to develop a completely regioselective TAD/naphthalene system. Additionally, naphthalene substitution allowed for a fine control over the cycloreversion kinetics with debonding half-life times ranging from 9 to 260 h at ambient temperature. In particular, 2,3-naphthalimides were found to yield both complete regioselectivity and fast dissociation kinetics, making it an interesting scaffold for the design of dynamic covalent materials. Consequently, 2,3-naphthalimide-based monomers were prepared and copolymerised with methyl methacrylate, methyl acrylate and N-isopropyl acrylamide. The copolymers were successfully photo-crosslinked with green light (λ = 515–525 nm) using a bis-triazolinedione compound to obtain organogels that spontaneously collapsed in the dark, which offers new opportunities to further advance the development and applications of light-stabilised dynamic materials.

Graphical abstract: Regioselective photocycloaddition for light-stabilised dynamic materials design

Supplementary files

Article information

Article type
Paper
Submitted
09 jan 2023
Accepted
28 feb 2023
First published
28 feb 2023

Polym. Chem., 2023,14, 1554-1566

Regioselective photocycloaddition for light-stabilised dynamic materials design

A. J. Ghielmetti, C. Barner-Kowollik, F. E. Du Prez and H. A. Houck, Polym. Chem., 2023, 14, 1554 DOI: 10.1039/D3PY00027C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements