Photobehaviour of phenyl-containing methacrylate polymers

The emisssion spectra and photobehaviour were investigated for compounds of general formula COO(CH₂)_nC₆H₅ (n = 1-3) located either in small compounds. diluted in methacrylate copolymers, or incorporated as pendant units in methacrylate homopolymers. All the polymers considered show only monomeric emission. In spite of this, the singlet lifetimes of the polymers were shorter than those of small model compounds. This result shows that, even in the absence of excimer formation. the photobehaviour of a polymer can be different from that of the corresponding monomeric model compounds. The quenching rate constants when n = 2 were measured in solvents.of different thermodynamic character employing several quenchers. The results show that preferential absorption is not significant in determining the quenching rate constant but that the polymer is more sensitive to steric hindrance than the model compound.