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
- negative photochromism
- reverse photochromism