Acrylates multifunctional

Multifunctional Acrylates in Rwidiation Curing Celanese Co., New York. 

It may also be possible to crosslink the acrylic PSA with the help of multifunctional acrylates or methacrylates [87], These monomers can simply be copolymerized with the balance of the other monomers to form a covalently crosslinked network in one step. Since the resulting polymer is no longer soluble, this typ)e of crosslinking is typically limited to bulk reactions carried out as an adhesive coating directly on the article or in emulsion polymerizations where the crosslinked particles can be dried to a PSA film. 

Interesting TPEs can be derived from binary and ternary blends of polyfunctional acrylates, ACM, and fluorocarbon rubber (FKM) [53]. During the blend preparation, the liquid multifunctional acrylate monomer used is polymerized and forms the continuous matrix encapsulating the... 

Crosslinked polymer networks formed from multifunctional acrylates are completely insoluble. Consequently, solid-state nuclear magnetic resonance (NMR) spectroscopy becomes an attractive method to determine the degree of crosslinking of such polymers (1-4). Solid-state NMR spectroscopy has been used to study the homopolymerization kinetics of various diacrylates and to distinguish between constrained and unconstrained, or unreacted double bonds in polymers (5,6). Solid-state NMR techniques can also be used to determine the domain sizes of different polymer phases and to determine the presence of microgels within a poly multiacrylate sample (7). The results of solid-state NMR experiments have also been correlated to dynamic mechanical analysis measurements of the glass transition (1,8,9) of various polydiacrylates. 

Additive Effects with Multifunctional Acrylates in UV Grafting. 

Table VIII. Synergistic Effect of Multifunctional Acrylates with Inorganic Salts (L) in Grafting Styrene to Polypropy- lene Initiated by UVa ...

Figure 3. Interaction of multifunctional acrylate with polymer radical by gamma irradiation.

DePass LR, Maronpot RR, Weil CS Dermal oncogenicity bioassays of monofunctional and multifunctional acrylates and acrylate-based oligomers. 7 Toxicol Environ Health 16 55-60... 

Blend of poly chloroprene and NBR Carbon black and multifunctional acrylate 50 15,000 20 (2,900)... 

Under UV-laser irradiation, photosensitive multifunctional acrylate resins become rapidly cross-linked and completely insoluble. The extent of the reaction was followed continuously by both UV and IR spectroscopy in order to evaluate the rate and quantum yield of the laser-induced polymerization of these photoresist systems. Two basic types of lasers emitting in the UV range were employed, either a continuous wave (C.W.) argon-ion laser, or a pulsed nitrogen laser. 

As a result of this study, it should be apparent that both C.W. and pulsed laser beams are capable of very efficiently initiating the cross-linking polymerization of multifunctional acrylate photoresists, provided adequate initiators are used to absorb the laser photons and generate the reactive species. The main advantages of this technology arise from the specific properties of the laser emission ... 

Cameron, T.P., Rogers-Back, A.M., Lawlor, T.E., Harbell, J.W., Seifried, H.E. Dunkel, V.C. (1991) Genotoxicity of multifunctional acrylates in the /zwo e//a/nianimahan-niicrosome assay and mouse lymphoma TK+ - assay. Environ, mol. Mutag., 17,264-271... 

Our use of bleachable photoinitiators to carry out polymerization at depth opens the possibility of controlling the vertical dimension photochemically rather than mechanically. We have used the photoreduction of Eosin by triethanolamine to sensitize the polymerization of multifunctional acrylates to demonstrate the principle. Irradiation is carried out at 514 nm with an Ar+ laser having a beam diameter of 1.4 mm. The volume of sample irradiated is a small fraction of the total, simulating the conditions found in stereolithography. Because of bleaching of the photoinitiator, the irradiation generates... 

It has been suggested in the literature that the a-amino radical is the species that initiates polymerization [210], This view is supported by our observation that, in spite of the relatively high quenching rate constant of Eosin triplet by triphenylamine (Table 5), the system Eosin-triphenylamine does not sensitize the photopolymerization of multifunctional acrylates. Thus, it is necessary that the amine contains a hydrogen at the a-carbon to be released as a proton after oxidation of the amine by the dye triplet. This deprotonation prevents the back electron transfer and forms a carbon radical that is sufficiently long-lived to be captured by the monomer. 

One of the limitations in using the xanthene dyes as photoinitiators is their relatively low solubility in nonpolar media. Solubility considerations become important in dye-sensitized photopolymerization of multifunctional acrylates in the absence of solvent. In the search for faster initiators for three-... 

A typical UV-cured coating has three or sometimes four main ingredients (1) a multifunctional acrylate monomer, (2) a reactive oligomer, (3) possibly a monoacrylate as reactive diluent, and (4) a photoinitiator (Table 2.20). 

As these reactive oligomers have a high viscosity, they are diluted with a multifunctional and if necessary a monofunctional acrylate monomer. The acrylate monomers reduce the viscosity of the mixture for easier application on substrates. The multifunctional acrylate monomers increase the crosslink density the monofunctional monomers decrease it. 

ADMET is a step growth polymerization in which all double bonds present can react in secondary metathesis events. However, olefin metathesis can be performed in a very selective manner by correct choice of the olefinic partner, and thus, the ADMET of a,co-dienes containing two different olefins (one of which has low homodimerization tendency) can lead to a head-to-tail ADMET polymerization. In this regard, terminal double bonds have been classified as Type I olefins (fast homodimerization) and acrylates as Type II (unlikely homodimerization), and it has been shown that CM reactions between Types I and II olefins take place with high CM selectivity [142], This has been applied in the ADMET of a monomer derived from 10-undecenol containing an acrylate and a terminal double bond (undec-10-en-l-yl acrylate) [143]. Thus, the ADMET of undec-10-en-l-yl acrylate in the presence of 0.5 mol% of C5 at 40°C provided a polymer with 97% of CM selectivity. The high selectivity of this reaction was used for the synthesis of block copolymers and star-shaped polymers using mono- and multifunctional acrylates as selective chain stoppers. 

The acrylate or methacrylate functional PIBs have also been used in UV-curable solventless coatings formulation in the presence of reactive diluents (multifunctional acrylate or methacrylate esters) and a UV-sensitizer [104]. The products were transparent, flexible films, with very little extractables, in which hard polyacrylate or polymethacrylate domains were dispersed in the soft PIB matrix. Tensile strength and ultimate elongation have also been obtained. 

Radiation Curable Reactive acrylates-vinyl 2EHA, NVP, etc Multifunctional di or triacrylates same as conventional but are usually substituted with acrylic-methacrylic acids 10-30% multifunctional acrylate 10-50% polymer 20-50% reactive solvent... 

A typical EB curable formulation will generally consist of a relatively high molecular weight solid or semi-solid difunctional acrylic resin reduced to application viscosity with combinations of liquid mono- and multifunctional acrylic monomers. These acrylic monomers, along with a few other selected polymerizable monomers, serve as reactive diluents and allow formulation of solvent-free compositions. Usually, small amounts of additives are also used in order to provide special properties, such as slip. 

Propargyl phenyl selenide is a versatile multifunctional acrylate synthon, as shown in Scheme 12. The (Uanion is prepared and reacted successively with an alkylating agent (R— X) and an electrophile (E ). The oxidative rearrangement of the propargylic selenoxide (35) to an allenic selenenate (36), and thence to the a-phenylselenoenone (37), forms the keystone of this synthetic method, and ovendl yields firom propargyl phenyl selenide are in the range of 38-68%. Further elaboration of (37) is possible... 

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