Monomers used photocuring

The preparation of other in vivo implants using photocurable coumarin end-groups and at least one lactone monomer selected from s-caprolactone, glycolide, or DL-lactide is described by the author [2]. 

NOA65 (Norland Optical Adhesive 65) is a commonly used photocurable polymer because its refractive index tip 1.52) is close to the tio of many commercial LC mixtures. Before U V curing, NOA65 is a clear and colorless liquid. The measurement of the monomer is fairly simple. However, in a practical device, such as a PDLC, all the monomers are cured to form a polymer... 

Neopentyl Glycol Diacrylate n (NPGDA) A highly reactive crosslinking monomer used in photocurable coatings. It provides solvent and strain resistance as well as improved response to light. 

The cured polymer samples used for physical property testing were prepared by photocuring 12 mil thick sheets of degassed and photosensitized monomer mixtures, using a mold composed of glass plates lined with polyester film and separated by a double thickness of vinyl electrical tape. A GE sunlamp was used for Illumination, and Darocure 1173 (E. Merck) was used as the photoinitiator. Hydrocarbon monomers were used as received from the manufacturers. All the vinyl group-containing compounds were stored at -5°C until use. 

Alkenyloxystyrene monomers such as 4-allyloxystyrene are useful components of photocured cationically polymerizable compositions. Used alone or in combination with divinyl ethers they provide low viscosity formulations, which are excellent solvents for commercial onium salt photoinitiators. Photocuring rates are comparable to vinyl ether monomers and the initially photocured alkenyloxystyrene polymers may be further heat processed to yield crosslinked phenolic type resins having outstanding thermal resistance properties. The new materials have good adhesive properties and are potentially useful where a combination of ease of processability and high performance is required. 

Para-t-butylphenyl glycidyl ether BPGE had a similar viscosity and C/O ratio as those of NA and had the best properties of the photocurable epoxies that were surveyed, but this monomer dewetted from Si substrates immediately after spin coating and formed a puddle at the substrate center. Other monofunctional epoxies exhibited the same behavior. Mixtures of BPGE with multifunctional aromatic epoxies wetted Si substrates and could be used as planarizing layers. 

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). 

Cho and Hong (2005) used photodifferential scanning calorimetry to investigate the photocuring kinetics of UV-initiated cationic photopolymerization of 1,4-cyclohexane dimethanol divinyl ether (CHVE) monomer with and without a photosensitizer, 2,4-diethylthioxanthone (DETX) in the presence of a diaryliodonium-salt photoinitiator. Two kinetic parameters, the rate constant (k) and the order of the initiation reaction (m), were determined for the CHVE system using an auto-catalytic kinetics model as shown in the following equation ... 

Photopolymer systems are photocurable resins incorporating reactive liquid monomers, photoinitiators, chemical modihers and hhers. Typically stereolithography utilizes UV radiation, so UV-curable systems are used. Free-radical-photopolymerizable acrylate systems were originally used however, newer cationic epoxy-resin and vinyl ether systems (based on iodinium- or sulfonium-salt cationic initiators) are now being utilized. 

NVK is used as a sensitizer of cationic photopolymerization. Cation-ically photopolymerizahle, or photocurable, compositions typically contain monomers or oligomers having the epoxy or the ether functionality, and a photoinitiator. The most commonly used photoinitiators employed for photoinduced cationic ring-opening pol5mierizations are diaryliodon-ium salts, or triarylsulfonium salts. 

However, for in sitM-formed systems, once the photocurable solution is injected and photopolymerized, it is very difficult to manipulate material properties via postcuring methods. For in vivo applications, it is also important to use biocompatible components (e.g., monomers and initiators) that produce nontoxic materials, leachables, and degradation products. 

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