Second-generation acrylic

A variety of acrylic copolymers are prepared by emulsion polymerization. A number of acrylic adhesives that are called reactive adhesives, modified acrylics, second-generation acrylics, or reactive-fluid adhesives have become available over the years. These formulations polymerize in the glue line and become an integral part of an adhesive assembly. 

Acrylic Adhesives. Acryhc stmctural adhesives can be classified into three major types the surface-activated acryhcs (anaerobics), the surface-activated second-generation acryhcs, and the cyanoacrylates. 

The second generation includes latices made with functional monomers like methacrylic acid, 2-hydroxyethyl acrylate [818-61 -17, acrylamide/75 -(9ti-/7, 2-dimethylaminoethylmethacrylate [2867-47-2] and sodiumT -vinyl-benzenesulfonate [98-70-4] that create in polymeric emulsifier. The initiator decomposition products, like the sulfate groups arising from persulfate decomposition, can also act as chemically bound surfactants. These surfactants are difficult to remove from the latex particle. 

The cross metathesis of acrylic amides [71] and the self metathesis of two-electron-deficient alkenes [72] is possible using the precatalyst 56d. The performance of the three second-generation catalysts 56c,d (Table 3) and 71a (Scheme 16) in a domino RCM/CM of enynes and acrylates was recently compared by Grimaud et al. [73]. Enyne metathesis of 81 in the presence of methyl acrylate gives the desired product 82 only with phosphine-free 71a as a pre-... 

One of the significant limitations of the use of first- and second-generation superplasticizers in ready-mixed flowing concrete is the rapid decrease in the initially achieved high workability and this constitutes one of the chief constraints to their wider acceptance. Therefore, a number of major producers of admixtures have sponsored active research to improve the workability retention characteristics of their superplasticizers. Some recent developments [48] have shown promise, among these are materials based on acrylate polymers (AP). The AP-based materials are reported to be more effective than SNF- or SMF-based surplasticizers in terms of water reduction, slump increase and slump retention. Figure 7.19 shows the remarkable improvement in the retention of workability produced by the AP type superplasticizer compared to an SNF type. 

Grubbs second generation catalyst can effectively catalyze the RCM of 2-vinylphenyl acrylates 670 to afford coumarins in high yields (Equation 270) <2003TL4199>. 

Acrylics such as these (the so-called second generation acrylics ) contain a rubbery polymer intended to toughen the matrix in a patented process, chloro-sulphonated polyethylene was grafted for this purpose to the acrylic materials. 

A technology developed at Du Pont75 combines the use of reactive sites on the oligomers with the initiation reaction. The resulting family of acrylic structural adhesives has become popularly known as second generation acrylics. They consist essentially of solutions of chlorosulfonated polyethylene (Du Pont Hypalon ) in acrylic or methacrylic monomers. The chlorosulfonyl groups present on the polymer will react with... 

Recycling experiments were performed using 2-[p-(2-methylpropyl)phenyl]acryl ic acid as a substrate. Upon the completion of the reaction, a small amount of water (2.5%) was added to the homogeneous reaction solution to accomplish complete phase separation. More than 99% of the second-generation catalyst was separated and extracted to the nonpolar hexane phase, whereas the polar product mainly stayed in the ethanol phase. The catalyst was reused at least four times, and showed similar reactivities and enantioselectivities on each occasion. 

Very recently, Fan et al. [13] reported on the use of a water-soluble PEO-substitut-ed first- and second-generation Frechet-type dendrimer with a chiral BINOL (1,1 -bi-2-naphthol) unit in catalysis. The enantiomeric excess in asymmetric hydrogenation of 2-[p-(2-methylpropyl)phenyl]acrylic acid with [RuCl(BINAP)(cymene)]Cl in an aqueous system was reported to increase upon addition of the dendritic... 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

Two component acrylic systems which are known as second generation acrylics in the U.S. and as "honeymoon adhesives" in Europe are discussed in Chapter 10. Acrylic resins have been... 

An unusual type of two component system has recently been introduced in the adhesive industry (1,). These are called reactive adhesives, second generation acrylics, toughened acrylics, modified acrylics (2) or "honeymoon adhesives" (in Europe). 

To a 1-liter flask equipped as in C above and containing 65.1 gm (0.757 mole) of methyl acrylate is added 28.4 gm (0.0272 mole) of the second generation polyamine dendrimer of D above dissolved in 84.6 gm of methanol over a 1.25 hr period. The resulting mixture is allowed to stand for 18 hr at room temperature (25°C) and then the excess methyl acrylate and methanol are removed under reduced pressure (2.0 mm Hg at 50°C) to yield 56.3 gm product (100% yield). 

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