Methacrylate, polymerization, methanol

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... 

Fig. 3.2. Methyl methacrylate polymerization initiated by hydrogen peroxide in methanol at room temperature. Sketch of the phase state in the beginning of the reaction as a function of the monomer concentration at constant hydrogen peroxide concentration 109)...

For methyl methacrylate polymerization U2), at conversion lower than 10% (Fig. 3.3), no autoacceleration is observed with respect to the formation of oligomers (p 1), contrary to that of polymers (p 2) in the presence of a solvent other than methanol. Similar results have been found for butadiene polymerization initiated by thermal decomposition of hydrogen peroxide at 120 °C 100). 

Pistoia has used electrochemically generated nitrate radicals to effect the bulk polymerization of acrylonitrile the system shows a remarkable postpolymerization effect which is affected by such factors as the anode material, current, temperature, stirring, electrolysis time, and HNO, concentration. Radical occlusion phenoma and the formation of oligomers limit the monomer to >oly-mer conversion. Pistoia has also reported the polymerization of acrylonitrile by the oxidation of sulphuric acid at the anode and has extended the work to the anodic polymerization of methyl methacrylate in methanol-sulphuric acid... 

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 ... 

Bead Polymerization Bulk reaction proceeds in independent droplets of 10 to 1,000 [Lm diameter suspended in water or other medium and insulated from each other by some colloid. A typical suspending agent is polyvinyl alcohol dissolved in water. The polymerization can be done to high conversion. Temperature control is easy because of the moderating thermal effect of the water and its low viscosity. The suspensions sometimes are unstable and agitation may be critical. Only batch reaciors appear to be in industrial use polyvinyl acetate in methanol, copolymers of acrylates and methacrylates, polyacrylonitrile in aqueous ZnCh solution, and others. Bead polymerization of styrene takes 8 to 12 h. 

In another study, uniform composite polymethyl-methacrylate/polystyrene (PMMA/PS) composite particles in the size range of 1-10 fim were prepared by the seeded emulsion polymerization of styrene [121]. The PMMA seed particles were initially prepared by the dispersion polymerization of MMA by using AIBN as the initiator. In this polymerization, poly(7V-vinyl pyrolli-done) and methyl tricaprylyl ammonium chloride were used as the stabilizer and the costabilizer, respectively, in the methanol medium. Seed particles were swollen with styrene monomer in a medium comprised of seed particles, styrene, water, poly(7V-vinyl pyrollidone), Polywet KX-3 and aeorosol MA emulsifiers, sodium bicarbonate, hydroquinone inhibitor, and azobis(2-methylbu-... 

ABA type poly(hydroxyethyl methacrylate) (HEMA) and PDMS copolymers were synthesized by the coupling reactions of preformed a,co-isocyanate terminated PDMS oligomers and amine-terminated HEMA macromonomers312). Polymerization reactions were conducted in DMF solution at 0 °C. Products were purified by precipitation in diethyl ether to remove unreacted PDMS oligomers. After dissolving in DMF/toluene mixture, copolymers were reprecipitated in methanol/water mixture to remove unreacted HEMA oligomers. Microphase separated structures were observed under transmission electron microscope, using osmium tetroxide stained thin copolymer films. 

Polymerization of triphenylmethyl methacrylate in the presence of a chiral anion catalyst results in a polymer with a helical structure that can be coated onto macroporous silica [742,804). Enantioselectivity in this case results from insertion and fitting of the analyte into the helical cavity. Aromatic compounds and molecules with a rigid nonplanar structure are often well resolved on this phase. The triphenylmethyl methacrylate polymers are normally used with eluents containing methanol or mixtures of hexane and 2-propanol. The polymers are soluble in aromatic hydrocarbons, chlorinated hydrocarbons and tetrahydrofuran which, therefore, are not suitable eluents. 

The anionic polymerization of the MM block was initiated with fluorenyllithium (14) in THF at -78°C. After several hours, t-butyl methacrylate was introduced, and the polymerization was allowed to slowly rise to room temperature. The reaction was quenched with a few drops of methanol and precipitated from ligroin. The dried polymer was analyzed by NMR, IR, and GPC. The 1H NMR spectrum displays signals at 0.85, 1.02, and 1.13 (shoulder) ppm for the... 

Syntheses. Isotactic poly(methyl methacrylate) was synthesized by the method of Tsuruta et al. (9 ). Under a nitrogen atmosphere, a quantity of 6 mL (0.056 mole) of methyl methacrylate (MMA) dried over 4A molecular sieve was dissolved in 24 mL of similarly dried toluene. To the glass vial containing the reaction was added 0.65 mL of 1.6 M n-butyllithium, and the reaction was kept at -78°C in a dry ice/isopropanol bath. The polymerization was halted 24 hr later with the addition of hydrochloric acid and methanol (methanol/water 4.1 by volume). The polymer was dried in vacuo at 50°C, redissolved in methylene chloride, precipitated by being poured into water-containing methanol, and dried in vacuo at 50°C. Tacticlty and composition were verified with % NMR. Yield 47%. 

The polymerization of 2-(diethylamino)ethyl methacrylate, DEAEMA, was studied under different conditions. It was shown that the best system providing narrow molecular weight distribution polymers involved the use of p-toluenesulfonyl chloride/CuCl/HMTETA as the initiator/catalyst/ligand at 60 °C in methanol [72]. Taking advantage of these results, well-defined PDEAEMA-fr-PfBuMA block copolymers were obtained. The synthesis was successful when either fBuMA or DEAEMA was polymerized first. Poor results with bimodal distributions were obtained when CuBr was used as the catalyst. This behavior was attributed to the poor blocking efficiency of PDEAEMA-Br and the incomplete functionalization of the macroinitiator. 

Table 10.5 gives the uses of acetone. A very important organic chemical that just missed the top 50 list, methyl methacrylate, is made from acetone, methanol, and hydrogen cyanide. Approximately 1.2 billion lb of this compound is manufactured and then polymerized to poly(methyl methacrylate), an important plastic known for its clarity and used as a glass substitute. The synthesis is outlined as follows. 

Solvents 1 and 2 are known to be good solvents for poly(methyl methacrylate) solvent 3 readily dissolves polystyrene.The solubility tests show that the radically polymerized sample is insoluble in all three solvents.The solubility isthusdifferentfrom that of both poly(methyl methacrylate) and polystyrene.The anionically polymerized product dissolves on warming in the acetone/methanol mixture and also in acetonitrile it is insoluble in cyclohexane/toluene.The solubility is thus similar to that of poly(methyl methacrylate). For the cationically initiated polymerization the product is only slightly soluble in acetone/methanol, insoluble in acetonitrile, but very readily soluble in cyclohexane/toluene.The solubility thus resembles that of polystyrene. 

It was reported that, in the contrast to acrylic acid, methacrylic acid does not exhibit any template effect under conditions described. However, template effect appears if a solvent such as water or methanol is added, and also at higher temperatures of polymerization. 

The solvent used can change interaction between template and monomer. For instance polymerization of methacrylic or acrylic acid in water and in water-methanol mixtures proceeds with different rates which depend on the composition of the solvents mixture as pertaining from the results in Figure 8.14. 

Rates of polymerization of methacrylic acid or acrylic acid in water in the absence of template, PEG, was much higher than that for template polymerization. However, the rate decreases with methanol concentration increasing, while the rate of template... 

After hydrolysis by 2N methanol solution of H2SO4, the product was neutralized with KOH to pH=5 and methanol evaporated. The dry residue was expected to be poly(allilamine), polymethacrylic acid, and K2SO4. Indeed, after extraction with anhydrous methanol and acetone, poly(allilamine) was identified by NMR and IR spectrometries. After evaporation, solvent from the methanol part of the extract insoluble in chloroform part was obtained. After esterification by diazomethane the product was identified as polyfmethyl methacrylate) on the basis of IR and H-NMR spectroscopy. IR spectroscopy was applied in order to examine the copolymerization of multimethacrylate (p-cresyl-formaldehyde oligomers with methacrylic groups) with st3rrene. It was found that double bond peak at 1650 cm disappeared during the process and it was absent in the product of polymerization. Polymerization and... 

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