Photochromic performance of Donor-Acceptor-Stenhouse-Adducts in Polymer Binders and Solution

Rowan McDonough, Nick Rudgley, Oskar Majewski, Michael V. Perkins, Richard A. Evans, David Andrew Lewis

Research output: Contribution to journalArticlepeer-review

Abstract

Donor-acceptor Stenhouse adducts (DASAs) are an exciting new class of negative photochromic compounds, offering high colouration and rapid photo-switching speeds, however the relationship between binder properties and photo-switching behaviour of DASAs in films is poorly understood. The determination and analysis of rate constants of seven DASAs in five polymer binders showed a complex relationship between the glass transition temperature (T g) of the binder, the solubility parameters of the matrix and the push-pull nature of the donor and acceptor moieties. The rate constants of photo-switching steps that require large degrees of molecular motion such as the actinic and thermal carbon-carbon double bond rotations (k bleach and k −1) were found to be highly dependent on the T g of the polymer binder, with higher T g binders restricting these processes, resulting in slower switching rates and impacting changes in colour intensity. Correlation of rate constants with the Hansen solubility parameter for solvents and binders revealed strong relationships between the sum of the polarity and hydrogen bonding parameters (δP+δH) and the actinic and thermal carbon-carbon double bond rotations (k bleach and k −1). This is attributed to changes in the zwitterionic resonance contributions of the triene with increases in these two solubility parameters.

Original languageEnglish
Number of pages10
JournalChemPhotoChem
Early online date27 Apr 2022
DOIs
Publication statusE-pub ahead of print - 27 Apr 2022

Keywords

  • DASA
  • donor-acceptor Stenhouse adduct
  • photochromism
  • negative photochromism
  • reverse photochromism

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