Interestingly, this approach did not provide any improvement in photofatigue of spiropyrans. On the other hand, they noticed that when the concentration of SP in the film was reduced, the degree of photodegradation also reduced, implying that aggregation of MC also has important role in the photodegradation process.
A similar conclusion was drawn by Arai et al. and Tork et al. while studying photodegradation of MC in solution [29] and polymer matrixes [30], respectively.
The work of these research groups indicates that reducing the degree of motion of MC reduces the possibility of interaction between MC molecules and has beneficial effects on reducing the photofatigue.
Therefore, since covalent attachmentdrastically limits the movement of MC it should result in films
showing improved photofatigue.