Photoinitiation of Acrylate Polymerization By 2-Methyl-1- [4-(Methylthio)Phenyl]-2-Morpholino-Propan-1-one - some Effects of the Morpholino Substituent

N-Isopropylmorpholine (IPM) was used as a model to investigate the properties of the morpholino substituent present in 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (1). It was shown by real time IR (RTIR) spectroscopy, photocalorimetry, bulk polymerization studies and the curing of thin films that IPM acts as a physical quencher for the triplet state of 1 and that it is a very poor hydrogen donor. Thus any interaction of the ground state of 1 with its triplet state is likely to lead to physical quenching, thereby reducing the initiating efficiency of 1. Evidence is also presented that the use of high concentrations of N-methyldiethanolamine can lead to reduction of the triplet state of 1, thereby enhancing the initiating efficiency of 1. It was confirmed that thioxanthones can sensitize the alpha cleavage of 1

Spontaneously designed, self-assembled and oriented ZnO nanorods by photoinduced polymerization of epoxydiacrylate formulation in the presence of 2-mercapto-thioxanthone

Here we report an environmentally friendly, fast, efficient and low cost method for in-situ preparation of ZnO nanorods in polymer matrix which is obtained using epoxydiacrylate formulation by UV irradiation. Compared to our previous study, the shape of the ZnO nanoparticles even with the same photoinitiator was found to mainly depend on the polymer matrix, but another important finding that was seen from the SEM images is that the type of photoinitiator helped for spontaneous self-assembly and orientation of ZnO nanoparticles. This very important issue arose when the one component Type II photoinitiator, namely, 2-mercapto thioxanthone was used in formulation. Self-assembly and orientation of ZnO nanorods in polymer were not the case either with Thioxanthone and Thiophenol or in the presence of Type I photoinitiator. All these experimental results for synthesis of ZnO nanoparticles in hydrophilic and hydrophobic polymer matrices may help to understand the effect of photoinitiator and polymer

The effect of heavy metals on the anthracene-Me-beta-cyclodextrin host-guest inclusion complexes

Anthracene was used to form an inclusion complex with methylated--cyclodextrin (Me-beta-CD) in water. In aqueous Me--CD solution, typical fluorescence emission of anthracene was observed. Benesi-Hildebrand's method was used to obtain the stoichiometry of the anthracene-Me--CD complex. The Stern-Volmer quenching constants, K-sv, and fluorescence quantum yields were calculated according to changes in the fluorescence emission intensity of anthracene-Me-beta-CD inclusion complexes by adding various amounts of Pb2+ and Cd2+ salts in water. The K-sv values and fluorescence quantum yields indicate that Pb2+ salts quench the anthracene-Me-beta-CD inclusion complexes more efficiently than Cd2+ salts

Thioxanthone based 9[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one as a visible photoinitiator

Photoinitiators that operate in the visible range of the electromagnetic spectrum have widespread applications. Thioxanthone based 9[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one (TX-MPA) was synthesized and the characterization of this initiator was confirmed by spectral analysis methods. TX-MPA has excellent absorption properties in the visible range (epsilon(480) (nm) =3576 L/mol.cm). Photophysical studies; fluorescence quantum yield (Phi(f)=0.22, DPA), phosphorescence lifetime (tau(p)=115 ms) and triplet lifetime (tau=190 ns) were explored. To explore the initiation mechanism of TX-MPA, besides the photophysical and photochemical studies, the polymer (PMMA) obtained from the photopolymerization studies was subjected to a phosphorescence study and tau(p) was found to be 105 ms compared to 115 ms for the initiator TX-MPA which proved attachment of the initiator to the polymer. Possibly both intermolecular and intramolecular hydrogen abstraction, occur during the initiation stage depending on the concentration of the initiator. (C) 2013 Elsevier B.V. All rights reserved