Polymerization of methyl methacrylate

Figure 6.3 shows some data which constitute a test of Eq. (6.26). In Fig. 6.3a, Rp and [M] are plotted on a log-log scale for a constant level of redox initiator. The slope of this line, which indicates the order of the polymerization with respect to monomer, is unity, showing that the polymerization of methyl methacrylate is first order in monomer. Figure 6.3b is a similar plot of the initial rate of polymerization—which essentially maintains the monomer at constant con-centration—versus initiator concentration for several different monomer-initiator combinations. Each of the lines has a slope of indicating a half-order dependence on [I] as predicted by Eq. (6.26).

AIBN was synthesized using C-labeled reagents and the tagged compound was used to initiate polymerization of methyl methacrylate and styrene. 

Arnett + initiated the polymerization of methyl methacrylate in benzene at ... 

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 ... 

Because the polymerization occurs totally within the monomer droplets without any substantial transfer of materials between individual droplets or between the droplets and the aqueous phase, the course of the polymerization is expected to be similar to bulk polymerization. Accounts of the quantitative aspects of the suspension polymerization of methyl methacrylate generally support this model (95,111,112). Developments in suspension polymerization, including acryUc suspension polymers, have been reviewed (113,114). 

Bulk Polymerization. This is the method of choice for the manufacture of poly(methyl methacrylate) sheets, rods, and tubes, and molding and extmsion compounds. In methyl methacrylate bulk polymerization, an auto acceleration is observed beginning at 20—50% conversion. At this point, there is also a corresponding increase in the molecular weight of the polymer formed. This acceleration, which continues up to high conversion, is known as the Trommsdorff effect, and is attributed to the increase in viscosity of the mixture to such an extent that the diffusion rate, and therefore the termination reaction of the growing radicals, is reduced. This reduced termination rate ultimately results in a polymerization rate that is limited only by the diffusion rate of the monomer. Detailed kinetic data on the bulk polymerization of methyl methacrylate can be found in Reference 42. 

The same PVP series were also tried for the dispersion polymerization of styrene in the ethanol medium by using AIBN as the initiator and aerosol OT as the costabilizer [84]. PVP K-15 usually yielded polymeric particles with a certain size distribution and some coagu-lum. The uniform products were obtained with PVP K-30 and PVP K-90 in the presence of the costabilizer. The tendencies for the variation of the final particle size with the stabilizer concentration and with the molecular weight of the stabilizer were consistent with those obtained for the dispersion polymerization of methyl methacrylate [84],... 

Plexiglas, a clear plastic used to make many molded articles, is made by polymerization of methyl methacrylate. Draw a representative segment of Plexiglas. 

Formation of block polymers is not limited to hydrocarbon monomers only. For example, living polystyrene initiates polymerization of methyl methacrylate and a block polymer of polystyrene and of polymethyl methacrylate results.34 However, methyl methacrylate represents a class of monomers which may be named a suicide monomer. Its polymerization can be initiated by carbanions or by an electron transfer process, the propagation reaction is rapid but eventually termination takes place. Presumably, the reactive carbanion interacts with the methyl group of the ester according to the following reaction... 

As an example, consider the polymerization of methyl methacrylate, initiated by a,a -azobisisobutyronitrile.4 The dependence of the initial rate on the concentration of the initiator is displayed in Fig. 1-1, which shows them on a double logarithmic scale. The points define a straight line with a least-squares slope of0.496. Clearly the reaction is half-order with respect to the concentration of the initiator. 

A plot of the initial reaction rate versus concentration, on logarithmic scales. The reaction is the polymerization of methyl methacrylate, and the concentration is that of the initiator, azobisisobutyronitrile. The slope is 0.496, showing that the reaction is half-order with respect to the initiator concentration. 

Anionic Polymerization of Methyl Methacrylate 3.1 Basic Observations... 

Our understanding of the intricacies of anionic polymerization of methyl methacrylate was greatly improved during the last 15years by the meticulous and persistent work of the Mainz group. To appreciate fully the progress made in this field it is advisable to summarize the older studies and the ideas developed in those days. 

The difficulties encountered in the early studies of anionic polymerization of methyl methacrylate arose from the unfortunate choice of experimental conditions the use of hydrocarbon solvents and of lithium alkyl initiators. The latter are strong bases. Even at —60 °C they not only initiate the conventional vinyl poly-addition, but attack also the ester group of the monomer yielding a vinyl ketone1, a very reactive monomer, and alkoxide 23). Such a process is described by the scheme. 

Fig. 2. Arrhenius plots of the rate constants of the anionic polymerization of methyl methacrylate in THF as the solvent and with Na+ orCs+ as the counterion. (R. Kraft, A. H. E. Muller, V. Warzelhan, H. Hocker, G. V. Schulz, Ref.35>)...

Although the low temperature polymerization of methyl methacrylate in polar solvents such as THF was believed to proceed without termination, a more exhaustive investigation55) revealed some slow termination processes resulting from the formation of a, not yet specified agent, supposedly produced in the initiation step. Since the nature of the terminating agent is still unknown it is premature to discuss here the proposed schemes of this termination process. 

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). 

In this short initial communication we wish to describe a general purpose continuous-flow stirred-tank reactor (CSTR) system which incorporates a digital computer for supervisory control purposes and which has been constructed for use with radical and other polymerization processes. The performance of the system has been tested by attempting to control the MWD of the product from free-radically initiated solution polymerizations of methyl methacrylate (MMA) using oscillatory feed-forward control strategies for the reagent feeds. This reaction has been selected for study because of the ease of experimentation which it affords and because the theoretical aspects of the control of MWD in radical polymerizations has attracted much attention in the scientific literature. 

The first is diffusion capture. This theory was originally proposed by Fitch and Tsai (13) for the aqueous polymerization of methyl methacrylate. According to this theory, any oligomer which diffuses to an existing particle before it has attained the critical size for nucleation is irreversibly captured. The rate of nucleation is equal to the rate of initiation minus the rate of capture. The rate of capture is proportional to both the surface area and the number of particles. 

Figure 5. Effect of autoacceleration on the precipitation polymerization of methyl methacrylate (2). The curves, from left to right, are for the diluents cyclohexane t-hutylsterate heptane and bulk.

The polymerization of methyl methacrylate (MMA) by Cu(ll) amidinate complexes (Scheme 222) in combination with alkyl aluminum complexes has been reported. The preferred alkylating agent is methylalumoxane (MAO) in... 

The polymerization of methyl methacrylate produces poly(methyl methacrylate), an exceptionally clear plastic sold under the names Plexiglas or Lucite as a shatter-proof substitute for glass in windows, doors, and other glazing applications. 

Polymerization of methyl methacrylate in supercritical carbon dioxide with PDMS based stabilizers A study on the effect of stabilizer anchor groups... 

Fig. 11.—The course of the polymerization of methyl methacrylate at 50°C in the presence of benzoyl peroxide at various concentrations of monomer in benzene. (Schulz and Harborth. q...

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