Fatigue of Donor‐Acceptor Stenhouse Adducts in Polymer Matrices and Solution

Abstract

The fatigue performance of a range of donor-acceptor-Stenhouse-adducts (DASAs) has been investigated to identify degradation mechanisms. The dyes were found to fatigue with and without exposure to light in both solution and in films.Excluding light below about 430 nm resulted in almost complete thermal recovery after exposure, however, a range of common film additives including hindered amine light stabilizers (HALS) and other additives (especially bases) were shown to react with the DASAs resulting in irreversible fatigue. The rate of fatigue was also found to increase with the relative strength of the donor and acceptor moieties in the molecule.

Donor–acceptor Stenhouse adduct functionalised polymer microspheres

“…It should be noted that the stability of 3 rd generation DASAs at these high temperatures is questionable, especially given the recent insights that stronger electron withdrawing acceptors are more susceptible to degradative processess. 67 However, this is mainly an issue in polar, protic solvents and, furthermore, no change in colour was observed in our case, which suggests that degradation/ retro reaction to yield free furan adduct did not occur in the present case. Monitoring of the photoisomerisation behaviour of the DMs by UV-Vis spectroscopy was possible using an integrating sphere UV-Vis spectrophotometer.…”

“…Attempts to improve the thermal recovery by heating the DMs up to 100 °C in the dark did not lead to any further recovery. It should be noted that the stability of 3 rd generation DASAs at these high temperatures is questionable, especially given the recent insights that stronger electron withdrawing acceptors are more susceptible to degradative processess 67 . However, this is mainly an issue in polar, protic solvents and, furthermore, no change in colour was observed in our case, which suggests that degradation / retro reaction to yield free furan adduct did not occurring in the present case.…”

“…When solvated, DASA-polymers exhibit significantly improved switching behaviour compared to dry, solid-state conditions. In the solid state, effective and reversible switching of polymer-bound DASAs is dependent on the polymer's glass transition temperature (T g ) 41,47 . When held at or above the host polymer's T g , DASA switching kinetics markedly improve 38,41,46 .…”

“…In the solid state, effective and reversible switching of polymer-bound DASAs is dependent on the polymer's glass transition temperature (T g ). 41,47 When held at or above the host polymer's T g , DASA switching kinetics markedly improve. 38,41,46 Studies by Sroda et al have also shown that the level of DASA functionalisation itself affects T g and elastic modulus of the host polymer, 38 while Yap et al demonstrated polymer chain-length dependence on DASA switching performance, with shorter chains (of ∼20 monomer units) showing faster switching compared to longer chainlengths (of ∼100 monomer units).…”

Visible-Light-Assisted Donor–Acceptor-Stenhouse-Adduct-Based Reversible Photoswitching on a Laser-Structurable OrmoComp Substrate

“…A reasonable extent of photobleaching has been observed, which is in accordance with the fatigue resistance study of liquid-phase analogues in the literature. 33,34 2.8. Investigation of the Influence of Aqueous Conditions on OrmoComp−DASA Photoswitching.…”