Photoinitiated free radical

J. Hutchison, "Photoinitiated Free Radical Chaia Reaction," Vol. 11, Energy Kesearch Abstracts Abstract No. 51555, Electricity Council Research Centre, 1986. 

Mn2(CO)io in a simple photoinitiated free radical polymerization. The antiplatelet activity of these polymers were compared with that of poly(ether-Wrethane) carrying the hydantoin residues in side chains. 

Photoinduced effects, in hydrogenated amorphous silicon, 22 139 Photoinduced electron transfer, 19 111 Photoinitiated cationic curing, J 0 414-415 Photoinitiated cross-linking, 15 157 Photoinitiated free-radical... 

Photoinitiated free radical polymerization proceeds via three main steps ... 

Primary, and Secondary Reactions in Photoinitiated Free-Radical Polymerization of Organic Coatings... 

Photoinitiated free radical polymerization is a typical chain reaction. Oster and Nang (8) and Ledwith (9) have described the kinetics and the mechanisms for such photopolymerization reactions. The rate of polymerization depends on the intensity of incident light (/ ), the quantum yield for production of radicals ( ), the molar extinction coefficient of the initiator at the wavelength employed ( ), the initiator concentration [5], and the path length (/) of the light through the sample. Assuming the usual radical termination processes at steady state, the rate of photopolymerization is often approximated by... 

One approach to this problem is to start with the alkyl terminated surfaces and carry out chemical transformations of the methyl end group. Chidsey and co-workers employed this approach by forming sulfonyl chloride terminal groups via a photoinitiated free radical reaction of CI2 and SO2 with the original methyl-terminated monolayer [45]. These were then converted to sulfonamides by reaction with amines. Schematically this two-step reaction scheme can be written as ... 

In contrast, photoinitiated free radical polymerization of glycidyl methacrylate and trimethylolpropane trimethacrylate in the presence of porogenic solvent affords a monolithic plug within the column that serves as a frit. This procedure represents a simple approach to reproducible fabrication of frits even in capillaries with large inner diameters. 

Photocurable coatings are widely used for metal, plastics wood and paper. Photoinitiated free-radical polymerization, however, can only be applied to vinyl monomers. The studies of Crivello have broadened the scope of monomers. In addition, photoinitiated cationic polymerization is not sensitive toward oxygen (air). Photoinitiated free-radical polymerization sometimes requires working in inert atmosphere in order to avoid the inhibition through oxygen1). 

Photoinitiated Free Radical Polymerization by Using Pyridinium... 

Representative Kinetic Data on Reactions of Photoinitiator Free Radicals... 

The effect of pulsed discharge on plasma polymerization may be viewed as the analogue of the rotating sector in photoinitiated free-radical chain growth polymerization. The ratio r of off time I2 to on time li, r = (t2/h), is expected to influence the polymerization rate depending on the relative time scale of I2 to the lifetime of free radicals in free-radical addition polymerization of a monomer. This method was used to estimate the lifetime of free radicals in conventional photon-initiated free radical polymerization. 

Tasdelen, M. A., Kiskan, B., Yagci, Y., Photoinitiated Free Radical Polymerization using Benzoxazines as Hydrogen Donors, Macromol. Rapid Commun. 2006, 27, 1539 1544. 

Y. Yagci and W. Schnabel, New aspects on the photoinitiated free-radical promoted cationic polymerization. Makromol. Chem. Macromol. Symp. 1992, 60, 133-143. 

Photoinitiated free-radical chlorination of (10) using phenyliodine dichloride is directed exclusively to the C(9) position, probably as a result of the conformation of the steroid placing the C(l) complexed to the template iodine atom close to the C(9) hydrogen. Dehydrochlorination then places a double bond in the C(9)-C(l) position. 

Triplet diradicals react with organic molecules in a very similar manner to RO radicals (Sect. 4.3.4) and are useful for photoinitiating free radical oxidations these photooxidations therefore closely resemble oxidations by other oxy radicals and will not be considered further. 

Easic Principles Practical Photochemistry General Considerations Carbonyl Compounds a-Cleavage Carbonyl Compounds Hydrogren Abstraction Steroids Carbonyl Compounds Cycloaddition Enone and Dienone Rearrangements Alkenes Isomerisation and Rearrangement Alkenes Cycloaddition Alkenes Photo-Cxidation Terpenoids Aromatic Compounds Isomerisation and Cycloaddition Practical Photochemistry Scale-up Aromatic Compounds Substitution and Cydisation Alkaloids Photoinitiated Free-radical Chain Reactions. 

Yu, C., Xu, M., Svec, F., and Frechet, J. M. J., Preparation of monolithic polymers with controlled porous properties for microfluidic chip applications using photoinitiated free radical polymerization,... 

Scheme 10.1 Reaction scheme illustrating the photoinitiated free radical polymerization of monomer M, commonly a compound with a C=C bond.

Beyazit, S. Aydogan, B. Osken, L Ozturk, T. Yagci, Y. (2011). Long wavelength photoinitiated free radical polymerization using conjugated thiophene derivatives in the presence of onium salts Polym. Chem., 2 pp(1185-1189). 

One useful property of cationic polymerization is that it is not air inhibited. In the absence of nucleophilic impurities, there are no inherent modes of termination. Thus, the polymerization may continue for long periods (hours to days) after the light is turned off, in contrast to photoinitiated free radical polymerization (24). This post-cure should be useful for laminating two opaque materials, in that irradiation of the adhesive followed by lamination should result in a well cured adhesive, although it may take 1-2 days to form maximum bond strength. 

Kahveci MU, Beyazkilic Z, Yagci Y (2010) Polyacrylamide cryogels by photoinitiated free radical polymerization. J Polym Sci Polym Chem 48 4989 994... 

The most common restoratives comprise a mineral filler mixed with a vinyl monomer (often called a resin), which undergo photoinitiated free radical Chain polymerization. Typical components inclnde the adduct of bis-phenol A and glycidy methacrylate (bis-GMA) or nrethane dimethacrylate (UDMA), camphorquinone initiator (activated by a visible bine light sonrce of 480 nm) and a filler such as zirconia or borosilicate glass, which can comprise 70% by mass of the system and provides the strength . The whole is referred to as a composite . 

The methods used to prepare NC gels are simple and versatile, i.e., injection of reaction solutions into closed vessels followed by polymerization at ambient temperature. Hence, NC gels can be readily formed in various shapes and sizes, such as films, sheets, rods, spheres, hollow tubes, etc. (Fig. 4a) [21,29]. NC gels can also be prepared by photoinitiated free-radical polymerization using very low concentrations (e.g., 0.1 wt% relative to the monomer) of a hydrophobic photoinitiator in aqueous systems (Fig. 4b) [48], Furthermore, the other type of NC gel, i.e., tetra-PEG-based NC gels, with good biocompatibility can be prepared by incorporating clay nanoparticles into the tetra-PEG network [30],... 

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