Polymerizations of epoxy resins

All of these species (XIV, XV) have been for the most part applied towards function in the olefin polymerization arena use of these novel anions for the stabilization of other electrophilic species remains to be explored. Recently, the imidazolide anion XVI, as well as the perfluorinated tetraaryl borate derived from the diborane IX of Chart 2, have been used to stabilize iodonium cations.222 These cations are used as photoinitiators for cationic polymerization of epoxy resins in photolithography applications. While use of the [B(C6F5)4] led to a breakthrough in this area of research,223 higher activities are observed for more WCAs. 

The second patent [94] does not give further information about the synthesis but describes an application of these products — UV curing of coatings for optical fibers. Telechelics diols are used as coreagents for cationic polymerization of epoxy resins. Such coatings are composed of ... 

In our laboratory, we have found that triarylsulfonium salts (III) in which the anions are of the type BF , AsFg , PFg , SbFg , etc., are excellent photoinitiators for the polymerization of epoxy resins as well as a variety of other monomers (12, 13). Similar results have also been reported by another group of investigators (14). 

The addition of THF to benzophenone sensitized polymerization of epoxy resin CY-179 results in a dramatically increased relative polymerization rate in the presence of lAsF, and a small increase in the presence of jy S AsF (compare Tables 1 and 2). Similarly, the addition of THF or isopropanol results in large product quantum yields ( Cp > 2) for benzophenone sensitized decomposition of -8 1 AsF, but only small increases in the decomposition of-8ls AsF ( 0.2). Quantum yields > 1... 

The formation of networks by addition polymerization of multifunctional monomers as minor components included with the monofunctional vinyl or acrylic monomer is industrially important in applications as diverse as dental composites and UV-cured metal coatings. The chemorheology of these systems is therefore of industrial importance and the differences between these and the step-growth networks such as amine-cured epoxy resins (Section 1.2.2) need to be understood. One of the major differences recognized has been that addition polymerization results in the formation of microgel at very low extents of conversion (<10%) compared with stepwise polymerization of epoxy resins, for which the gel point occurs at a high extent of conversion (e.g. 60%) that is consistent with the... 

Scheme 3A Ring-opening polymerization of epoxy resins.

Preparation of a novel cationic photoinitiator [Cp-Fe-diphenylether] PFe was reported. It was claimed that polymerizations of epoxy resins and eyeloaliphatic epoxides can be photo initiated by this compound effectively. Addition of benzoyl peroxide to this photoinitiator promotes the... 

Bis(4-Ammo-3-Methylcyclohexyl)Methane (Polymerization of Epoxy Resins)... 

Yamakage A, Ishikawa H, Saito Y, Hattori A (1980) Occupational scleroderma-like disorder in men engaged in the polymerization of epoxy resins. Dermatologica 161 33-44... 

The Photo-Differential Scanning Calorimetry (photo-DSC) [10] was used to study the cure kinetics of UV-initiated photo-polymerization of epoxy resin monomers and vinyl ether in presence of cationic photo-initiator, mainly Cyracure UVI-6976, former Cyracure UVI-6974, which consists of a mixture of dihexafluoroantimonate of S, S, S, S -tetraphenylthiobis (4,1-phenyllene) disulfonium and hexafluoroantimonate of diphenyl (4-phenylthiophenyl) sulfonium (CAS no. 89452-32-9 and 71449-78-0) at 50 wt. % in propylene carbonate - Figure 44 [11]. 

Hillmyer, M.A., Lipic, P.M., Hajduk, D.A., Almdal, K., and Bates, F.S. (1997) Self assembly and polymerization of epoxy resin amphiphilic block copolymer nanocomposites. J. Am. Chem. Soc.,... 

Gregory patented Ultraviolet Curable Resin Compositions Having Enhanced Shadow Curing Properties in 2001. This patent has the same idea as Dixon s patent, that is, use photopolymerization at the surface of a filled resin to trigger a thermal front. Gregory went beyond using peroxide-cured vinyl resins. He used dialkyl iodonium salts, sensitized by a-hydroxy ketones, that produced Lewis acids upon UV irradiation. The Lewis acid triggered cationic polymerization of epoxy resins and vinyl ethers. The heat from the photoinitiated process decomposes peroxides into radicals that react with the iodonium salts to produce Lewis acids. 

Lewis acids, compounds with empty orbitals capable of accepting electron pairs, initiate cationic polymerization of epoxy resins. In this case the propagating species is a positive ion. The most commonly used Lewis acids are... 

Lewis acids have been shown to initiate polymerization through carbonium ion formation and therefore the presence of a suitable coinitiator has been found necessary in order to generate these ions. The polymerization of epoxy resins by BF3 complexes has been proposed to follow the mechanism shown in Scheme 29. 

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