Radical copolymerization of acrylic monomers. VIII. Copolymerization of methyl methacrylate with methyl α-p-chlorobenzylacrylate and methyl methacrylate with methyl α-p-methoxybenzylacrylate

Free-radical copolymerization of methyl methacrylate with methyl α-p-chlorobenzylacrylate and methyl methacrylate with methyl α-p-methoxybenzylacrylate have been studied in benzene solution at 40°C. Although a simple copolymerization model fits the composition data, the kinetic behavior of both copolymerization systems are analyzed from simple and reversible copolymerization models, taking into account the relatively low ceiling temperature of both methyl α-(p-substituted benzyl)acrylates and considering that the overall rate of copolymerization drastically decreases with the increase of the corresponding methyl α-(p-substituted benzyl)acrylate molar fraction in the feed.     

Radical polymerization and copolymerization of methyl α-(2-carbomethoxyethyl)acrylate,a dimer of methyl acrylate,as a polymerizable α-substituted acrylate

Polymerization and copolymerization of methyl α-(2-carbomethoxyethyl)acrylate (MMEA), which is known as a dimer of methyl acrylate, were studied in relation to steric hindrance-assisted polymerization. The propagating polymer radical from MMEA was detected as a five-line spectrum and quantified by ESR spectroscopy during the bulk polymerization at 40–80°C. The absolute rate constants of propagation and termination (κ_p and κ_t) for MMEA at 60°C (κ_p = 19 L/mol s and κ_t = 5.1 × 10⁵ L/mol s) were evaluated using the concentration of the propagating radical at the steady state. The balance of the propagation and termination rates allows polymer formation from MMEA. The polymerization rate of MMEA at 60°C was less than that of MMA by a factor of about 4 at a constant monomer concentration. Although no influence of ceiling temperature was observed at a temperature ranging from 40 to 70°C, addition-fragmentation in competition with propagation reduced the molecular weight of the polymer. The content of the unsaturated end group was estimated to be 0.1% at 60°C to the total amount of the monomer units consisting of the main chain. MMEA exhibited reactivities almost similar to those of MMA toward polymer radicals. It is concluded that MMEA is one of the polymerizable acrylates bearing a substituted alkyl group as an α-substituent. Characterization of poly(MMEA) was also carried out. © 1996 John Wiley & Sons, Inc.     

Syntheses of methyl α-dl-mycaminoside, methyl α-dl-oleandroside, methyl β-dl-cymaroside, methyl α-dl-tyveloside and methyl α-dl-chromoside C

Five rare hexoses, which are components of antibiotics or cardiac glycosides, have been synthesized as methyl glycosides through a common intermediate methyl 2,3-dehydro-2,3,6-trideoxy-α-dl glucopyranoside (7). Epoxidation and subsequent treatment with dimethylamine of7 afforded methyl α-dl-mycaminoside (9). The addition reaction of MeOH to12 gave methyl α-dl-oleandroside (15) and methyl β-dl-cymaroside (17). The hydroxymercuration and subsequent reduction of12 afforded methyl α-dl-chromoside C (19) and methyl β-dl-tyveloside (25).     

Radical copolymerization of acrylic monomers. VI. Copolymerization of methyl methacrylate with methyl α-benzylacrylate

Free-radical copolymerization of methyl methacrylate and methyl α-benzylacrylate has been studied in benzene solutions at 40 and 60°C. A simple copolymerization model fits the composition data at both temperatures. However, considering that the ceiling temperature for the polymerization of methyl α-benzylacrylate in benzene solution (|M| = 5 mol/L) is 67°C and that the overall rate of copolymerization drastically decreases with respect to that of methyl methacrylate homopolymerization with an increase of the molar fraction of methyl α-benzylacrylate in the feed, the behavior of this system is analyzed from both simple and reversible copolymerization models.     

Cobalt complex bearing β‐ketoamine ligand: syntheses,structure, catalytic behavior for styrene and methyl methacrylate polymerization

Cobalt complex based on β‐ketoamine ligand [(Z)‐4‐((2,5‐dimethylphenylamino) (phenyl)methylene)‐3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one] was successfully synthesized. The produced catalyst showed satisfactory activities in the cobalt‐mediated radical polymerization of styrene and methyl methacrylate with the common initiator of AIBN. The resulting polymerizations have the characteristics of living radical polymerization and displayed a nearly linear correlation between the number‐average molecular weight and monomer conversion. Low polydispersity was obtained for all polymerizations, and the polydispersity index decreased with the increase of conversion. These improvements facilitate the implementation of styrene and methacrylate cobalt‐mediated radical polymerization, and open the door to the scale‐up of the process. Copyright © 2014 John Wiley & Sons, Ltd.     

Chemical synthesis of poly‐γ‐glutamic acid by polycondensation of γ‐glutamic acid dimer: Synthesis and reaction of poly‐γ‐glutamic acid methyl ester

α‐Methyl glutamic acid (L ‐L )‐, (L ‐D )‐, (D ‐L )‐, and (D ‐D )‐γ‐dimers were synthesized from L ‐ and D ‐glutamic acids, and the obtained dimers were subjected to polycondensation with 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride and 1‐hydroxybenzotriazole hydrate as condensation reagents. Poly‐γ‐glutamic acid (γ‐PGA) methyl ester with the number‐average molecular weights of 5000∼20,000 were obtained by polycondensation in N,N‐dimethylformamide in 44∼91% yields. The polycondensation of (L ‐L )‐ and (D ‐D )‐dimers afforded the polymers with much larger |[α]_D | compared with the corresponding dimers. The polymer could be transformed into γ‐PGA by alkaline hydrolysis or transesterification into α‐benzyl ester followed by hydrogenation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 732–741, 2001     

γ-radiation-initiated emulsion polymerization of n-butyl acrylate and of methyl methacrylate

We have investigated the γ-radiation-initiated polymerization of n-butyl acrylate (BA) and of methyl methacrylate (MMA) in aqueous emulsions stabilized with sodium lauryl sulfate (SLS). The reaction rate, as measured by a nonabsolute thermocouple technique, varies as the square root of emulsifier concentration for both monomers. In the case of BA, the dose rate exponent of the reaction rate is 0.7 ± 0.3, whereas the corresponding value for MMA is approximately 0.4. The overall activation energy of the BA polymerization is close to zero, whereas for MMA a value of 4.8 ± 2.1 kcal/mole has been found. The poly(butyl acrylate) molecular weight is effectively independent of soap concentration and of dose rate but decreases as the reaction temperature is increased in the range 30–70°C. The general conclusion drawn from this work is that these radiation-induced emulsion polymerizations differ little from conventionally initiated systems insofar as the reaction kinetics are concerned. Poly(butyl acrylate-g-methyl methacrylate) copolymers have been prepared by a direct irradiation method involving a poly(butyl acrylate) prepolymer seed latex. Some physical properties of this material have been examined.