Methyl methacrylate polymerization Grignard reagents

The addition of ethers to the reaction brought about a reduction in the isotactidty of the polymers. Goode, Owens, and Myers (20) studied the polymerization of methyl methacrylate with Grignard reagents and found similar results to the alkyllithium polymerizations. This group of workers efficiently utilized infrared as a means of determining the tactidty of the polymers. 

The initiation of methyl methacrylate polymerization by alkyl- and aryl-lithium compounds is a very complex process which has not been completely elucidated so far. Even less information is available on the efects of or-ganometals not containing lithium. Recently, the interest of some authors has centred on the application of Grignard reagents for the initiation of anionic polymerizations, especially of MMA [171, 172],... 

Methyl methacrylate polymerizations, initiated by oiganomagnesium compounds, also yield abnormal products. Here, the active centers are unusually persistent and stabile. In addition, the a-carbon atoms of the monomers were found to assume tetrahedral configurations.This suggests that the active centers contain covalent magnesium carbon bonds. Also, gel permeation chromatography curves of the products show that more than one active center operates independently. A pseudoanionic mechanism was therefore postulated for polymerizations of acrylic and methacrylic esters by Grignard reagents. 

Braun et al. [258] used a combination of tert-butyllithium (t-BuLi) and tetramefhy-lethylenediamine to create initiator sites at the surface of carbon black for the LASIP of styrene. Schomaker et al. [259] first immobilized a methyl methacrylate derivative on colloidal silica and after activation by a Grignard reagent polymerized MMA. 

Many dialkyl and diaryl cadmium compounds have found use as polymerization catalysts. For example, the diethyl compound catalyzes polymerization of vinyl chloride, vinyl acetate, and methyl methacrylate (45), and when mixed with TiCl can be used to produce polyethylene and crystalline polypropylene for filaments, textiles, glues, and coatings (45). With >50% TiCl diethyl cadmium polymerizes dienes. Diethyl cadmium maybe used as an intermediate ethylating agent in the production of tetraethyllead. The diaryl compounds such as diphenylcadmium [2674-04-6]> (C H Cd, (mp 174°C) are also polymerization catalysts. These compounds are also prepared using Grignard or arylUthium reagents in tetrahydrofiiran (THF) solvent but may be prepared by direct metal substitution reactions such as ... 

Nishioka, Watanabe, Abe, and Sono (48) carried out an extensive study of the Grignard reagent catalyzed polymerization of methyl methacrylate in toluene with respect to tactidty of the resulting polymers. The tactidty of the polymer was determined quantitatively by nuclear magnetic resonance analysis. It was found that the stereo-regularity depended on the nature of the R group of the Grignard... 

Anionic polymerization of poly(methyl methacrylate) (PMMA) using the Grignard reagent prepared from polymer 3L was also attempted for low molecular weight star polymers. The PMMA segment was essentially syndiotactic. 

Products from anionic polymerizations of methyl methacrylate catalyzed by Grignard reagents (RMgX) vary with the nature of the R and X groups, the reaction temperature, and the nature of the... 

It has been suggested that the broad molecular weight distribution of poly(methyl methacrylate) prepared in toluene with anionic initiator could be explained in terms of a combination of two narrower distributions produced simultaneously occurring mechanisms(1). Cottam et al.(2) suggested the existence of two active species uncomplexed and complexed with lithium methoxide, respectively, in the polymerization of MMA with BuLi. Recently it was reported that in the polymerization of MMA in a mixture of toluene and THF with Grignard reagent the polymers obtained consist of two components, methanol-soluble and methanol-insoluble polymers, which are considered to form at two distinct and independent active centers(3). In the polymerization of methyl a-ethylacrylate by BuLi in toluene there exist two types of active species which produce isotactic and syndictactic polymers, respectively(4). 

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