Radical polymerization, of acrylate monomer

Usually, free-radical initiators such as azo compounds or peroxides are used to initiate the polymerization of acrylic monomers. Photochemical (72—74) and radiation-initiated (75) polymerizations are also well known. At a constant temperature, the initial rate of the bulk or solution radical polymerization of acrylic monomers is first order with respect to monomer concentration and one-half order with respect to the initiator concentration. Rate data for polymerization of several common acrylic monomers initiated with 2,2 -azobisisobutyronittile (AIBN) [78-67-1] have been determined and are shown in Table 6. The table also includes heats of polymerization and volume percent shrinkage data. 

The free-radical polymerization of acrylic monomers follows a classical chain mechanism in which the chain-propagation step entails the head-to-tail growth of the polymeric free radical by attack on the double bond of the monomer. 

Polymerization employing Co complexes as catalysts or else polymers incorporating functionality that includes Co ions represent aspects of polymerization reactions of interest here. Cobalt-mediated free-radical polymerization of acrylic monomers has been reviewed.55 Co11 porphyrins act as traps for dialkylcyanomethyl radicals.1098 Alkyl complexes of Co(TMesP)... 

Much work on the preparation of nonaqueous polymer dispersions has involved the radical polymerization of acrylic monomers in the presence of copolymers having the A block the same as the acrylic polymer in the particle core 2). The preparation of polymer dispersions other than polystyrene in the presence of a PS-PDMS diblock copolymer is of interest because effective anchoring of the copolymer may be influenced by the degree of compatibility between the PS anchor block and the polymer molecules in the particle core. The present paper describes the interpretation of experimental studies performed with the aim of determining the mode of anchoring of PS blocks to polystyrene, poly(methyl methacrylate), and poly(vinyl acetate) (PVA) particles. 

Triphenylphosphine sensitizes the radical polymerization of acrylic monomers, such as methyl acrylate or methyl methacrylate (MMA), whereas styrene and vinyl acetate are not photosensitized. Complex formation between MMA and (C6H6)3P was spectroscopically observed. 

Controlled Free Radical Polymerization of Acrylic Monomers... 

In addition to catalysis of small molecule transformations and biocatalysis, non-functionalized LLC phases used as reaction media have also been found to accelerate polymerization reactions as well. For example, the L and Hi phases of the sodium dodecylsulfate/n-pentanol/sulfuric acid system have been found to lower the electric potential needed to electropolymerize aniline to form the conducting polymer, polyaniline [110]. In this system, it was also found that the catalytic efficiency of the L phase was superior to that of the Hi phase. In addition to this work, the Ii, Hi, Qi, and L phases of non-charged Brij surfactants (i.e., oligo(ethylene oxide)-alkyl ether surfactants) have been observed to accelerate the rate of photo-initiated radical polymerization of acrylate monomers dissolved in the hydrophobic domains [111, 112]. The extent of polymerization rate acceleration was found to depend on the geometry of the LLC phase in these systems. Collectively, this body of work on catalysis with non-functionalized LLC phases indicates that LLC phase geometry and system composition have a large influence on reaction rate. 

Polyamic acids are useful resists especially when containing 2,2 -dinitrodi-phenylmethane segments, while a Ti sapphire laser has been found to be effective for 3D curing and microfabrication. On a theoretical note, a direct correlation has been found between the calculated Boltzmann-averaged dipole moment and the measured maximum rate of photoinitiated radical polymerization of acrylic monomers. ... 

Brief Description of Incident This facility manufactured powder coatings and paint additives by a process using free-radical polymerization of acrylic monomers in flammable solvents. A customer requested more of an additive than the facility would normally make in a single batch, so managers decided to scale up the operation to produce the required amount for the order. The managers and most operators in this plant had been with the plant less than a year, and none of them had previous experience in manufacturing polymers. 

The free-radical polymerization of acrylic monomers takes place through the classical stepwise chain-growth mechanism, which is described as the head-to-tail addition of individual monomer units through attack of the monomer double bond and formation of a single bond between the newly incorporated monomer units. 

In a similar manner, extended-chain oligomeric polyesters, polyethers, and poly(dimethylsiloxane)s have been fitted with acrylate or methacrylate functional groups, and these materials find a multitude of practical uses such as UV-curable coatings and adhesives. The photoinitiated radical polymerizations of acrylic monomers and oligomers proceed very rapidly in the... 

Epoxies have been toughened with elastomer-dispersed phases with a decrease in modulus. Work by Balakrishnan et al. [35] utilized organo-montmorillonite as a dispersed phase in elastomer-toughened epoxies to recover this lost modulus. The montmorillonite was modified with octadecyl ammonium ion. The elastomer-dispersed phase in the epoxy was prepared by free radical polymerization of acrylic monomer within the epoxy. The acrylic elastomer-dispersed phase had epoxy functionality provided through the utilization of glycidyl methacrylate as a comonomer. 

Recently, various derivatives of dibenzoyldihydroxy methane have been used for free-radical polymerization of acrylic monomers [86]. Pho-tocalorimetric and real-time infrared (IR) investigations gave evidence that these compounds are excellent photoinitiators. 

The azobenzene moiety can also be incorporated in the side chain of poly aery late by radical polymerization of acrylate monomer with pendant azobenzene moiety. A typical synthetic procedure is given in Example 5 ... 

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