Polymerization free radical, methyl methacrylate

Methyl methacrylate Free radical polymerization similar to the above. Also susceptible to rapid anionic polymerizationinduced by RMgX or Na in liquid NHs CH, —CH,—C— 1 COOCH3 Tg 90 Amorphous, even when stretched. Hard. Soluble in aromatic hydrocarbons, esters, dioxane, etc. 

Allen, P. W., G. Ayrey, F. M. Merrett and C. G. Moore The use of [C14]-labelled initiators in determining the termination reaction in methyl methacrylate free radical polymerization the importance of molecular weight measurements. J. Polymer Sci. 22, 549 (1956). 

Krajnc, M., Poljansek, I., Golob, J. Kinetic modeling of methyl methacrylate free-radical polymerization initiated by tetraphenyl biphosphine. Polymer 42(9), 4153 162 (2001)... 

Buback M, Kowollik C. Termination kinetics of methyl methacrylate free-radical polymerization studied by time-resolved pulsed laser experiments. Macromolecules 1998 31 3211-3215. 

Begum F, Zhao H, Simon SL. Modehng methyl methacrylate free radical polymerization reaction in hydrophilic nanopores. Polymer 2012 53 3238-3244. 

The extruder can be used for a variety of polymerizations even if no preformed polymer is present.89 These include the continuous anionic polymerization of caprolactam to produce nylon 6,90 anionic polymerization of capro-lactone 91 anionic polymerization of styrene 92 cationic copolymerization of 1,3-dioxolane and methylal 93 free radical polymerization of methyl methacrylate 94 addition of ammonia to maleic anhydride to form poly(succin-imide) 95 and preparation of an acrylated polyurethane from polycaprolactone, 4,4 -methylenebis(phenyl isocyanate), and 2-hydroxyethyl acrylate.96 The technique of reaction injection molding to prepare molded parts is slightly different. Polyurethanes can be made this way by... 

Hydroxy-2-methylpropanenitrile is then reacted with methanol (or other alcohol) to yield methacrylate ester. Free-radical polymerization is initiated by peroxide or azo catalysts and produce poly(methyl methacrylate) resins having the following formula ... 

Fox and Schneckof carried out the free-radical polymerization of methyl methacrylate between -40 and 250 C. By analysis of the a-methyl peaks in the NMR spectra of the products, they determined the following values of a, the probability of an isotactic placement in the products prepared at the different temperatures ... 

For almost all applications unsaturated polyesters are dissolved in an unsaturated monomer capable of free-radical polymerization with the unsaturations in polyester chains. This polymerizable comonomer is generally styrene, but other compounds, such as methyl methacrylate, vinyl toluene, a-methylstyrene, and diallylphthalate, are also used in some applications. Upon heating and in... 

In the literature there is only one serious attempt to develop a detailed mechanistic model of free radical polymerization at high conversions (l. > ) This model after Cardenas and 0 Driscoll is discussed in some detail pointing out its important limitations. The present authors then describe the development of a semi-empirical model based on the free volume theory and show that this model adequately accounts for chain entanglements and glassy-state transition in bulk and solution polymerization of methyl methacrylate over wide ranges of temperature and solvent concentration. 

Balke, S.T., "The Free Radical Polymerization of Methyl Methacrylate to High Conversion", Ph.D. Thesis, McMaster University, Hamilton, Ontario (1972). 

Ring-opening polymerization of 2-methylene-l,3-dioxepane (Fig. 6) represents the single example of a free radical polymerization route to PCL (51). Initiation with AIBN at SO C afforded PCL with a of 42,000 in 59% yield. While this monomer is not commercially available, the advantage of this method is that it may be used to obtain otherwise inaccessible copolymers. As an example, copolymerization with vinyl monomers has afforded copolymers of e-caprolactone with styrene, 4-vinylanisole, methyl methacrylate, and vinyl acetate. 

Lignin, brown coal polymer of methacrylic acid, methacrylamide, hydroxyethyl acrylate, hydroxypropyl acrylate, vinyl acetate, methyl vinyl ether, ethyl vinyl ether, N-methylmeth-acrylamide, N,N-dimethylmethacrylamide, vinyl sulfonate, or 2-acrylamido-N-methylpropane sulfonic acid free radical polymerization of a water-soluble vinyl monomer in an aqueous suspension of coals [705,1847]... 

A critical survey of the literature on free radical polymerizations in the presence of phase transfer agents indicates that the majority of these reactions are initiated by transfer of an active species (monomer or initiator) from one phase to another, although the exact details of this phase transfer may be influenced by the nature of the phase transfer catalyst and reaction medium. Initial kinetic studies of the solution polymerization of methyl methacrylate utilizing solid potassium persulfate and Aliquat 336 yield the experimental rate law ... 

In 1981 we reported (2, 3) the first examples of free radical polymerizations under phase transfer conditions. Utilizing potassium persulfate and a phase transfer catalyst (e.g. a crown ether or quaternary ammonium salt), we found the solution polymerization of acrylic monomers to be much more facile than when common organic-soluble initiators were used. Somewhat earlier, Voronkov and coworkers had reported (4) that the 1 2 potassium persulfate/18-crown-6 complex could be used to polymerize styrene and methyl methacrylate in methanol. These relatively inefficient polymerizations were apparently conducted under homogeneous conditions, although exact details were somewhat unclear. We subsequently described (5) the... 

Ajayaghosh A, Francis R (1998) Narrow polydispersed reactive polymers by a photoiniti-ated free radical polymerization approach. Controlled polymerization of methyl methacrylate. Macromolecules 31 1436-1438... 

Ajayaghosh A, Francis R (1999) A xanthate-derived photoinitiator that recognizes and controls the free radical polymerization pathways of methyl methacrylate and styrene. J Am Chem Soc 121 6599-6606... 

In connection with the cause of the field influences on the cationic homopolymerization, it is interesting to study how free radical polymerizations are affected by an electric field. Table 1 shows that both the polymer yield and the degree of polymerization were not affected at all by the field, though the intensity was much higher than that applied to cationic systems. The situation was the same for free radical polymerizations of styrene by benzoylperoxide (72), and of methyl methacrylate by benzoylperoxide and azobisisobutyronitiile (77). 

It should be noted here that, when free radical polymerizations were carried out under an electric field using methyl methacrylate which had deliberately been allowed to absorb water, the polymerizing solutions showed high electric conductivity and gave lower conversion and degree of polymerization than in the absence of the electric field (11). The low... 

Trifonov and Panayotov (41) attempted to carry out anionic polymerizations of vinyl monomers with semiquinones generated at a cathode. Since semiquinones inhibit free-radical polymerization, anionic polymerization alone should take place in the system. When electrolysis of quinones was conducted in a solution of LiCl or N(CaH6)4I in DMF with mercury cathode, the catholyte turned to red or purple red in accordance with the semiquinones. The presence of free-radical produced on the quinone molecule was proved from the ESR spectrum. When each of the monomers, styrene, acrylonitrile and methyl methacrylate were added to the colored solutions, polymers were obtained. 

Early studies of the free radical polymerization of methyl methacrylate did not show a solvent influence (18, 22, 23, 24) and consequently no solvent dependent influence of the conversion on the tacticity (23). A solvent dependence on stereocontrol in methyl methacrylate polymerization was however found by Watanabe and Sono (25) as early as 1962. Apparently, their paper has been overlooked. A literature search and a recalculation of most of the published data showed solvent influences on stereocontrol to be the rule and not the exception (6). Later experimental data on methyl methacrylate in about 50 solvents (7) and in 14 solvents (8) confirmed the earlier findings of Watanabe and Sono (25). 

A similar result has been recently found for the free radical polymerization of methyl methacrylate in 14 solvents (32). All differences (Aff. — AHf/8) were found to be positive, but only three of the 14 differences (AH /g — AH. ). Again, isotactic triad formation is favored over heterotactic triad formation and heterotactic triad formation over syndiotactic with increasing temperature as long as the individual modes of addition are considered and not the net result. Except for meth-acrylic acid in alcohols (cf. Lando et al. (28)) no model is known which shows why a certain solvent acts differently from another one with respect to stereocontrol in free radical polymerization. 

A linear relationship between (AHf — Aff5 ) and (ASf — ASj ) is obeyed for all but one system checked so far. The compensation effect holds for different solvents and different initial monomer/solvent compositions, as Figure 1 shows for the s/i and i/s additions of the free radical polymerization of methyl methacrylate. 

Figure 2. Compensation plot for different modes of addition in the free radical polymerization of methyl methacrylate/ZnCk systems. Data from Otsu et al. (26) and Okuzawa et al. (27).

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