Photochemistry and photopolymerization activity ofp-nitroaniline in the presence ofN,N-dimethylaniline as a bimolecular photoinitiator system

Real-time kinetic study of the polymerization activity of the photoinitiator system p-nitroaniline/N,N-dimethylaniline by real time IR spectroscopy

“…Although these kinetic parameters exhibit the same dependence on the presence of DMA than that evaluated previously by Photo-DSC, their absolute values determined by IR are up to 50 times higher than the later ones 11) . These differences could be related to the strong effect of differential absorption or attenuation of the incident light intensity throughout a sample of 0.12 cm optical path lenght selected to follow the polymerization by Photo-DSC technique which is significatively reduced in a L 100 lm thick coating analyzed by RTIR spectroscopy.…”

“…The RTIR spectroscopy permits, from the recorded conversion versus time curves, to determine in a single run the induction period, the rate of polymerization and the amount of residual unsaturation in the cured polymer, all of them data of practical and theoretical significance 9) . Recently, we have examined the photochemistry and photopolymerization activity of a new photoinitiator system, based on p-nitroaniline (pNA) in the presence of an aromatic tertiary amine, N,N-dimethylaniline (DMA) acting as reducting agent [10][11][12][13] . The analysis of the polymerization kinetics by Photo-DSC revealed that the rate and quantum yield of polymerization (R p and b p , respectively) of dodecyl acrylate, commonly known as lauryl acrylate (LA), photoinitiated by the pNA/DMA system are much higher than those induced by other conventional bimolecular aromatic ketone photoinitiators of industrial importance, such as benzophenone and Michler's ketone.…”

Hologram recording in polyvinyl alcohol/acrylamide photopolymers by means of pulsed laser exposure

“…The reduced penetration of light into the sample ultimately leads to a decrease in the overall rate of polymerization. 21 Consequently, the top layer will be highly polymerized, while the bottom layer remains unaffected. As discussed previously, the laser repetition rate has an important effect on the response of the material.…”

Photosensitization of N,N-Dimethylaniline by N,N-Dimethyl-4-nitroaniline as a New Bimolecular Photoinitiation System for Polymerization

“…Irradiation of the sample for a long time does not modify the spectroscopic features aforementioned, which is a clear indication of a photoreduction process slower and less efficient than that induced for DMA in the presence of pNA. [10] Further information on the mechanism of the photoreduction of DMNA by DMA was obtained by studying the nature of the products generated in the reaction by GC-MS technique. Mass spec- trometric analysis of the irradiated samples allowed to isolate three main products, namely remaining DMNA and DMA as well as a compound of a molar mass of 136 D with a spectrum that could be assigned to N,Ndimethyl-1,4-benzenediamine (DMNAH 2 ).…”

“…The photosensitization process of the triplet state of DMA by DMNA is reflected in an enhancement of the polymerization efficiency with respect to other conventional bimolecular photoinitiators. [10] Moreover, and taking into account that the initiator is the active species in the absorption of the irradiation light, the low consumption of DMNA is assuring the same efficiency of the primary step of this initiating mechanism in the monomer polymerization. Consequently, higher initiation efficiency, achieved with a lower consumption of the initiator, represents an important advantage from an industrial point of view.…”