Polymerization of methacrylonitrile

Electron-transfer initiation from other radical-anions, such as those formed by reaction of sodium with nonenolizable ketones, azomthines, nitriles, azo and azoxy compounds, has also been studied. In addition to radical-anions, initiation by electron transfer has been observed when one uses certain alkali metals in liquid ammonia. Polymerizations initiated by alkali metals in liquid ammonia proceed by two different mechanisms. In some systems, such as the polymerizations of styrene and methacrylonitrile by potassium, the initiation is due to amide ion formed in the system [Overberger et al., I960]. Such polymerizations are analogous to those initiated by alkali amides. Polymerization in other systems cannot be due to amide ion. Thus, polymerization of methacrylonitrile by lithium in liquid ammonia proceeds at a much faster rate than that initiated by lithium amide in liquid ammonia [Overberger et al., 1959]. The mechanism of polymerization is considered to involve the formation of a solvated electron ... 

Accelerated Living Polymerization of Methacrylonitrile with Aluminum Porphyrin Initiators by the Activation of Monomer... 

For the anionic polymerization of methacrylonitrile (MAN), many initiators have been developed, which include alkali-metal alkyls such as butyllithium [42], triphenylmethylsodium [43], phenylisopropylpotassium [43], the disodium salt of living a-methylstyrene tetramer [44], alkali-metal amides [45], alkoxides [46], and hydroxide [47], alkali metal in liquid NH3 [48], quaternary ammonium hydroxide [49], and a silyl ketene acetal coupled with nucleophilic or Lewis acidic catalysts [50]. However, only a single example of the synthesis of PMAN with narrow molecular-weight distribution can be cited, and the reported number-average molecular weights were much higher than those calculated from the stoichiometry of the butyllithium initiator [42]. 

Polymerization of Methacrylonitrile with Methylaluminum Porphyrin in the Presence of Methylaluminum Diphenolate... 

Fig. 22. Polymerization of methacrylonitrile (MAN) with the living prepolymer of methy] methacrylate (MMA) (2)-methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) system [MAN]o/[2]o=50, [2]o=22.6 mM, CH2CI2 as solvent, rt, initial ratios of 3e to 2=3.0 ( ), 4.0 (A), and 10 ( ). Effect of the amount of Lewis acid 3e on the rate of polymerization...

Table 3.15. Results of the bulk polymerization of methacrylonitrile (MAN) initiated by different initiators at 90 °C ([I] = 3.5 mmol l"1) 361...

Overberger, C. G., E. M. Pearce and N. Mayes Polymerization of methacry-lonitrile with lithium in ammonia. J. Polymer Sci. 34, 109 (1959). Polymerization of methacrylonitrile with lithium. J Polymer Sci. 31,217 (1958). 

Alkali Metal-Ammonia Initiator Systems. Beaman (4) first discovered that sodium in ammonia was capable of initiating the polymerization of methacrylonitrile. It should be recalled that sodium and ammonia alone... 

Overberger, Yuki, and Urukawa (50) studied the polymerization of methacrylonitrile in the potassium-liquid ammonia system. The results obtained with potassium amide-ammonia were the same as with potassium-ammonia. Isobutyronitrile was detected in the reaction products, indicating that potassium amide was initiating the quantitative polymerization as in the styrene-potassium-ammonia system (93). It was also found that potassium hydroxide initiated polymerization of methacrylonitrile in liquid ammonia, but at a slower rate than potassium or potassium amide. 

Overberger, Yuki, and Urakawa (50) studied the polymerization of methacrylonitrile with potassium amide in liquid ammonia at — 78° and found that the molecular weight was independent of monomer concentration and catalyst concentration. It was shown that trace quantities of water had no effect on the degree of polymerization, but water in excess gave lower yield and degree of polymerization. Overberger, Pearce, and Mayes (49) found that lithium amide was ineffective as initiator for methacrylonitrile in liquid ammonia at — 78°. 

In the polymerization of methacrylonitrile initiated by butyllithium, the organometal is bound to nitrile groups [137]... 

Fig. 5. Plot of ycr1/2 vs. P of the growing radical for the polymerization of methacrylonitrile in DMF. Temperature 333 K, [AIBN] = 0.1 mol dm-3.

He was aware that termination reactions were of little importance, since successive additions of monomer could be made to polymerize after the complete reaction of the first added portion, even after the reaction mixture had been allowed to stand for some time. The relative efficiency of a group of initiators was also described. In the polymerization of butadiene, for instance, the deep red colour of cumylpotassium disappeared almost immediately, whereas with triphenylmethylsodium, the colour persisted during the polymerization process. With metallic sodium initiation, polymerization was shown to proceed at both ends of the polymer chain via an a,co-disodium adduct of the diene. It can be said, therefore, that by 1936 the essential characteristics of the process had been described, but interest in this topic was limited for many years afterwards. A few papers appeared in the literature. Beaman [6], in 1948, described the polymerization of methacrylonitrile and methylmethacrylate by sodium and triphenylmethylsodium in liquid ammonia, and similar experiments with styrene were described in 1949 [7, 8] using sodium or potassium amide as initiator. 

Use of sodium metal to initiate the polymerization of methacrylonitrile is an example of this type of process (Eq. 22.28). 

TYPES OF POLYMERIZATION Free-radical or ionic polymerization of methacrylonitrile (2-cyanopropylene) in bulk, emulsion, or solution group-transfer polymerization also has been used. Ionic polymerization in inert solvents can produce either amorphous poly(methacrylonitrile) (by use of anionic catalysts such as n-butyllithium) or primarily isotactic poly(methacrylonitrile) (by use of coordination catalysts such as ethylberyllium or diethylmagnesium). 

In all these cases, different modes of monomeric linkage are obtained, but the structure of the monomeric unit itself remains the same. Some other monomeric units, however, can be abnormally incorporated into the polymer even under normal polymerization conditions. In the free radical polymerization of methacrylonitrile, for example, a limited amount of polymerization occurs via the nitrile group, as can be shown spectroscopically ... 

Sugimoto, H., Saika, M., Hosokawa, Y., Aida, T., and Inoue, S., 1996, Accelerated Living Polymerization of Methacrylonitrile with Aluminum Porphyrin Initiators ity Activation of Monomer or Growing Species. Controlled Synthesis and Properties of Poly(medtyl methactylate-b-methaciylonitrile)s, Macromolecules, 29 3359... 

Just like aciylonitrile, methacrylonitrile does not polymerize thermally but polymerizes readily in the presence of free-radical initiators. Unlike polyacrylonitrile, polymethaciylonitrile is soluble in some ketone solvents. Bulk polymerizations of methacrylonitrile have the disadvantage of a long reaction time. The rate, however, accelerates with temperature. The polymer is soluble in the monomer at ambient conditions... 

Emulsion polymerization of methacrylonitrile is a convenient way to form high molecular weight polymers. With proper choices of emulsifiers, the rates may be increased by increasing the numbers of particles in the latexes. At a constant rate of initiation, the degree of poljmierization of methacrylonitrile increases rather than decreases as the rate of polymerization rises. " ... 

Sugimoto, H. Saika, M. Hosokawa, Y. Aida, T. Inoue, S. Accelerated living polymerization of methacrylonitrile with aluminum porphyrin initiators by activation of monomer or growing species. Controlled synthesis and properties of poly(methyl methacrylate-i>-methacrylonitrile)s. Macromolecules 1996, 29, 3359-3369. 

Anionic Polymerization of Bicyclobutane-1- arbonitrile -We inquired whether anionic polymerizations of could also be carried out. The most successful anionic polymerizations of methacrylonitrile (the vinyl analog of la), have been those of Joh and his colleagues (14,, who used dialkylmagnesium and magnesium dialkylamide iniHators. Therefore we utilized them with bicyclobutane-l-carbonitrile. 

Polymethacrylonitrile n (PMAN) Poly(2-methyl-2-propenenitrile) A thermoplastic obtained by the polymerization of Methacrylonitrile, a vinyl monomer containing the nitrile group. The homopolymer has good mechanical strength and high resistance to solvents, acids, and alkalis, but discolors at molding temperatures. 

The polymerization of methacrylonitrile from the living pol3mier of methyl methaciylate takes place in the presence of a Lewis base such as pyridine at room temperature to give the corresponding block copolymer of uniform, controlled block lengths. In this case, the acceleration effect of visible light irradiation is remarkable. 

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