Acrylics first-generation

Grubbs first generation metathesis catalyst 145 was found to be an active catalyst for the Kharasch addition, provided its metathesis activity for the chosen olefin is low [206]. Snapper and coworkers found at the same time that the Grubbs I olefin metathesis catalyst is efficient for the Kharasch addition of less activated halides, such as CHC13, 1,1,1-trichloroethane, or ethyl trichloroacetate, to olefins like styrenes, acrylates, or acrolein [207, 208]. 

Conventional or first generation acrylic adhesives are the earliest examples of this technology. They contain methacrylated monomers, a variety of polymers, an... 

Table 1 Conventional, or First Generation, Acrylic Adhesives... 

Table 2 Bond Performance of First Generation Acrylic Adhesives ...

Typical bond performance of adhesives of the first generation type is shown in Table 2. The adhesives have good adhesion to thermoplastics such as polystyrene, ABS, and poly(vinyl chloride), to wood and rubber, and to steel and aluminum provided the metals are clean. It can also be seen from this table that adhesion to galvanized steel is lower than to other metals. Bonding to galvanized steel was a problem with first generation acrylic adhesives but it has been overcome with more recent embodiments of this technology covered later in this chapter. 

The emergence of the DH acrylic adhesives occurred concurrent with the introduction of the so-called HP or high performance acrylic adhesives. This type of system, as with the DH types, offered users the ability to bond through oily metals, but did not require the use of awkward oily primers. They also were based on formulations that contained specialty adhesion promoting components, often contained monomers that were less flammable than first generation products, and often were also considerably lower in odor. 

The use of inorganic binding materials and components based on organic binding acrylic, predominantly as dispersions in water or dissolved in organic solvents, led to first-generation brick and concrete paints. The main drawback of these coatings is comparatively short service life. 

The first and still dominant route to synthesize PAMAM dendrimers is via the divergent growth approach as reported by Tomalia etal in 1985. It involves a Michael addition reaction between a core, comprising primary amines, and an excess of methyl acrylate (Figure 17). Once the reaction has reached completion, an aminolysis step of the methyl esters with an excess of a-alkanediamines yields the first-generation PAMAM... 

The first generation and intermolecular capture of an unfettered indole-2,3-quinodimethane (3) was reported by Marinelli (Scheme 7, equation 1) [50]. IQD 3 also reacts in anticipated Diels-Alder fashion with methyl acrylate and with another molecule of 3. A different means to generate an IQD was described by Srinivasan and Saroja (equation 2) [51], a method founded on the early work of Cava involving a,a -dibromo-o-xylene [1, 2], Thus, treatment of A-benzoyl-2,3-bis(bromomethyl)indole with sodium iodide (DMF, 50 °C) in the presence of dienophiles (p-ben-zoquinone, dimethyl acetylenedicarboxylate, A-phenylma-leimide) afforded the expected Diels-Alder adducts from... 

Tetramethyl piperidines were first identified as potent traps for free radicals in the 1960s and the first generation of HAS was commercialized in the 1970s as effective light stabilizers for polyethylene, polyamides, and acrylics. But the mechanism by which HAS act to stabilize polymer radicals is still not entirely clear. 

Carboxylation of polymers is usually conducted by first generating free radical on the polymer molecules, then reacting these with either acrylic acid, maleic anhydride, styrene-maleic anhydride, or Diels-alder adducts of maleic anhydride [23]. Thus, in this case the reactive blending is performed by using low molecular reactive agents that functionalize selected polymers. 

More recently, Wagner and coworkers used rhodium catalysts for the alkylcatecholborane-mediated hydroboration of PBD.In their first study, the authors used catecholborane-mediated hydroboration to give alkoxyamines via nitroxide oxidation with TEMPO (Fig. 20A). With RhCl(PPh3)3 as the catalyst, hydroboration of PBD occurred preferentially at the vinyl —CH=CH2 bonds on the side chains, whereas internal olefins were converted to a smaller extent. The total functionalization was approximately 50%. In their next study, the authors used the same chemistry to achieve 74% hydroboration/nitroxide oxidation of C=C bonds in PBD. They subsequently used alkoxyamine substituents as macromolecular initiators for the controlled nitroxide-mediated polymerization of styrene or butyl acrylate to generate comb-shaped polymers (Fig. 20B). Fligh conversions were achieved after 24 h, and PD Is were low in aU cases (M /M = 1.3-1.5). 

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