Vinyl polymerization. 364. Polymerization of methyl methacrylate initiated with benzaldehyde

Benzaldehyde (PhCHO) is found to be able to initiate the radical polymerization of methyl methacrylate (MMA). The rate of polymerization is expressed by the following equation: R_p = const[PhCHO]^0.5[MMA]^1.5. The overall activation energy is estimated to be 56.3 kJ mole^?1. The mechanism of polymerization is discussed.     

Atom transfer radical polymerization of methyl methacrylate catalyzed by ion exchange resin immobilized Co(II) hybrid catalyst

Ion exchange resin immobilized Co(II) catalyst with a small amount of soluble CuCl₂/Me₆TREN catalyst was successfully applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in DMF. Using this catalyst, a high conversion of MMA (>90%) was achieved. And poly(methyl methacrylate) (PMMA) with predicted molecular weight and narrow molecular weight distribution (M_w/M_n = 1.09–1.42) was obtained. The immobilized catalyst can be easily separated from the polymerization system by simple centrifugation after polymerization, resulting in the concentration of transition metal residues in polymer product was as low as 10 ppm. Both main catalytic activity and good controllability over the polymerization were retained by the recycled catalyst without any regeneration process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1416–1426, 2008     

Vinyl polymerization. 351. Polymerization of methyl methacrylate initiated with α-amylase and copper(II) ion in water

The polymerization of MMA initiated by a system of α-amylase, cupric chloride, and water was carried out. The effects of the amounts of water, copper(II) ion, and MMA on the conversion of MMA were studied. The overall activation energy was estimated to be 55 kJ/mole. Urea, known as a denaturing agent for protein, was found to increase the rate of polymerization and efficiency of grafting onto α-amylase.     

Vinyl polymerization by metal complexes. III. Vinyl polymerization initiated by oligoamide and cupric ion system

Polymerization of methyl methacrylate and other vinyl monomers was studied in the presence of oligoamide (?-aminocaproic acid, its dimer, trimer, tetramer, and pentamer) and cupric ion in aqueous media. The polymerization was found to be of free-radical character and selective for the type of vinyl monomer. Carbon tetrachloride can accelerate the polymerization. The initiation mechanism of the polymerization is discussed. Spectroscopic measurements were indicative of formation of 1:1 complex between oligoamides and cupric ion in aqueous NaClO₄ solution. Some chemical and physical properties of the resulting polymers were measured.     

Radical polymerization of methyl methacrylate in the presence of isotactic poly(methyl methacrylate)

Methyl methacrylate (MMA) was polymerized by radical initiation at 25°C in DMF in the presence of preformed isotactic PMMA (iMA) with about 90% isotactic triads and different M?_v's, viz., iMA-1: 7.2 × 10⁵; iMA-2, 5.0 × 10⁵; iMA-3, 3.5 × 10⁵; iMA-4, 1.25 × 10⁵; and iMA-5, 1.15 × 10⁵. The MMA:iMA ratio was 6:1. The collected polymers were separated into two fractions by extraction with boiling acetone and characterized by 60 MHz NMR. It is found that the M?_v of the polymer formed ran parallel to the M?_v of iMA. In all cases syndiotactic PMMA (s-PMMA) was produced which associated with the isotactic substrate to form acetone-insoluble stereocomplexes. The syndiotactic polymers probably consist of long syndiotactic and heterotactic sequences. The syndiotacticity decreased with conversion and was generally highest in the presence of iMA-1. With iMA-1 even the formation of some additional i-PMMA (in the acetone-insolubles) was indicated, especially in the later stages of the polymerization. Characterization of the acetone-soluble fractions indicated that i,s-stereoblock polymers were also produced, of which the persistence ratios ρ increased with the M?_v of iMA. From these results it is concluded that this reaction differs from the conventional radical polymerization and can be considered a stereospecific replica polymerization, the driving force being the strong tendency of i- and s-PMMA to associate. The formation of i,s-stereoblock polymers and additional i-PMMA indicates that s-PMMA in its turn can also act as a polymer matrix.     

Radical polymerization of methyl methacrylate in the presence of low-molecular-weight poly(methyl methacrylate)

The kinetics of the bulk radical polymerization of methyl methacrylate and the structure and properties (physicomechanical and thermomechanical, as well as diffusion and sorption) of the polymers were examined in relation to the amount of low-molecular-weight poly(methyl methacrylate) added.     

Radical polymerization of methyl methacrylate initiated by an enolizable ketone–carbon black system

The polymerization of methyl methacrylate (MMA) initiated by an enolizable ketone (R₁? CO? CH₂? CO? R₂)-carbon black system was investigated. Although enolizable ketone itself could not do so, the polymerization of MMA was initiated by enolizable ketone in the presence of carbon black. In addition, a chloranil-enolizable ketone system was able to initiate the polymerization of MMA. It was found that the enol form of the ketone and quinonic oxygen groups on the carbon black surface played an important role in the initiation system; namely, it was considered that the polymerization was begun by the ketone radical (R₁? CO? CH? CO? R₂) formed by a one-electron transfer reaction from enolate ion to quinonic oxygen groups. The effect of solvent on the process was also studied. The rate of the polymerization increased, depending on the solvent used, in the following order: benzene < 1,4-dioxane < dimethyl sulfoxide < N,N-dimethylformamide < N-methyl-2-pyrrolidone. Furthermore, it became apparent that during the polymerization poly(methyl methacrylate) was grafted onto the carbon black surface (grafting ratio was ca. 40% when benzene was used as solvent) and the carbon black obtained gave a stable colloidal dispersion in organic solvent.     

Ultrasonically initiated emulsion polymerization of methyl methacrylate

The ultrasonically initiated emulsion polymerization of methyl methacrylate (MMA) was investigated. Experimental results show that sodium dodecyl sulfonate (SDS) surfactant plays a very important role in obtaining a high polymer yield, because in the absence of SDS, monomer conversion is near zero. Thus, the surfactant serves as an initiator and as interfacial modifier in this system (MMA/H₂O), and the monomer conversion increases significantly with increasing SDS concentration. An increase in the reactor temperature also leads to an increase in the monomer conversion. An appropriate increase in the N₂ purging rate also leads to higher conversion. The conversion of MMA decreases with increasing monomer concentration because of the higher viscosity of the system. With the experimental results, optimized reaction conditions were obtained. Accordingly, a high monomer conversion of about 67% and a high molecular weight of several millions can be obtained in a period of about 30 min. Furthermore, transmission electron micrographs show that the latex particles prepared are nanosized, indicating a promising technique for preparing nanoscale latex particles with a small amount of surfactant. In conclusion, a promising technique for ultrasonically initiated emulsion polymerization has been successfully performed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3356–3364, 2001     

Polymerization of methyl methacrylate induced with the peracid-type ion exchange resin

The polymerization of methyl methacrylate initiated with a peracid-type resin was studied. The peracid-type resin was prepared by the oxidation of cation-exchange resin (Amberlite IRC-50) with 60 wt-% aqueous hydrogen peroxide in the presence of p-toluenesulfonic acid. It was found that the peracid-type resin was effective as an initiator for polymerization of methyl methacrylate. The kinetic investigation indicated that this polymerization proceeded by a radical mechanism, and the overall activation energy of polymerization was 15.8 kcal/mole. No effect of macromolecular catalyst on steric structure of the resulting polymer was observed. Some graft polymer was formed in bulk polymerization. On the other hand, only a homopolymer was obtained in solution polymerization. From the results obtained, a possible mechanism of initiation with the peracid-type resin is proposed and discussed.     

The polymerization of methyl methacrylate by ion pairs

The reactions of the polymethylmethacrylate anion have been investigated at 200 K and 250 K in both THF and 9/1 toluene/THF. Sodium-α methyl styrene tetramer and fluorenyl sodium were used as initiators. Only ion pair reactions were investigated. The rate constant of monomer addition to the ion pair at 200 K was determined to be 80 ± 6 M^?1 sec^?1. At 250 K in the presence of excess monomer, the poly MMA anion reacts with the monomer vinyl function and the monomer ester function at comparable rates. Once fully reacted, the poly MMA anion terminates very slowly in THF at 250 K by an intermolecular mechanism. This rate of termination is enhanced in the toluene/THF system. No evidence was found for different reaction mechanisms for the two initiators.     

Free radical polymerization of methyl methacrylate initiated by the diphosphine Mo(0) complexes

The polymerization of methyl methacrylate MMA catalyzed by [Mo(CO)₄L₂] [L₂ = diphenylphosphinomethane (dppm), diphenylphosphinoethane (dppe) or diphenylphosphinopropane (dppp)] has been studied. The activity of these single‐component catalysts depends on the length of the (CH₂)_n bridge of diphosphine ligand. Thus, the dppm derivative displays higher activity than dppe or dppp ligands. These complexes, as free radical initiators, afforded the methyl methacrylate polymerization in chlorinated solvents. The mechanism of the polymerization was discussed and a radical mechanism was proposed. Copyright © 2006 John Wiley & Sons, Ltd.     

Vinyl polymerization. CCCXXXIX. Effect of chain length of nylon 3 on the polymerization of methyl methacrylate initiated with the system of nylon 3, copper(II) ion,and water

It was found recently that the system of nylon 3, copper(II) ion, and water could initiate a radical polymerization of methyl methacrylate(MMA). In the present paper, the effect of average chain length of the molecules of nylon 3 on the rate of polymerization of MMA was studied. The rate increased with the chain length of nylon 3. This result was explained well by the fact that the shorter nylon 3 forms a complex with copper (II) ion more easily than longer nylon 3. It was assumed that the shorter nylon 3 fills three or four coordination sites of copper(II) ion and loses the ability to initiate the polymerization. The efficiency of grafting of MMA and the degree of polymerization of MMA homopolymer were independent of the chain length of nylon 3.