Polymerization initiation and transient spectrometric studies of water-soluble and -insoluble tert-butyl aroylperbenzoates

Similar lifetimes of the S1 state (λmax ∼ 590 nm, τS1 −7.55 to 9.11 ps in acetonitrile) of the tert-butyl aroylperbenzoates (BAPs), water-insoluble (1 and 2) and water-soluble (3) having the perester moiety para (1 and 3) and meta (2) to the benzophenone carbonyl group, were obtained by ultrafast pump-probe techniques. The lifetime of the T1 state of 2 (λmax ∼ 510 nm, τT1 > 1.2 ns) was, however, found to be at least four times higher than those of 1 and 3 (λmax ∼ 560 nm, τT1 ∼ 0.3 ns). The effectiveness of 1-3 as photoinitiators for the polymerization of 1-vinyl-2-pyrrolidinone (NVP) and lauryl acrylate (LAC) was compared. Perester 2 is a better thermal and photoinitiator for NVP polymerization than either 1 or 3. The photopolymerization of LAC initiated by either 1 or 2 is an efficient process.