Polymerizability of methyl α-substituted acrylates containing methoxycarbonyl groups

Dimethyl 4-methyl-1-pentene-2,4-dicarboxylate ( 3 ) and trimethyl 4-methyl-1-octene-2,4,7-tricarboxylate ( 4 ) are not radically homopolymerizable. Dimethyl 1-hexene-2,4-dicarboxylate ( 5 ) polymerizes slowly to yield a small amount of oligomers. Homopolymerization of dimethyl 1-butene-2,4-dicarboxylate ( 6 ) affords a high-molecular-weight polymer. Radical copolymerization of these methyl α-substituted acrylates (M₂) with styrene (M₁) was carried out at 60°C using AIBN, and the following monomer reactivity ratios were obtained; 3 : r₁ = 0,983, r₂ = 0,000; 4 : r₁ = 0,938, r₂ = 0,000; 5 : r₁ = 0,672, r₂ = 0,119; 6 : r₁ = 0,566, r₂ = 0,195. The polymerizability of these methyl acrylate derivatives is influenced by the steric effect of the α-substituents.     

Atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate with α,α‐dichlorotoluene as initiator; a kinetic study

The atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate with α,α‐dichlorotoluene ( DCT ) as initiator results in the respective chlorotelechelic polymers. From a kinetic point of view, however, the polymerization of styrene and methyl methacrylate show a different behavior: for the polymerization of styrene DCT is a bifunctional, for the polymerization of methyl methacrylate it is a monofunctional initiator.     

Methine and α-methyl proton resonance in methyl acrylate/methacrylonitrile copolymers

Methyl acrylate (A)/methacrylonitrile (M) copolymers, prepared by emulsion and solution polymerization at 50°C, were characterized by 220 MHz NMR spectroscopy. The methine and α-methyl proton resonances of such copolymers consisted of three peak patterns, individual resonance areas being assignable to protons centered in various A or M centered triads. Triad fractions determined from methine and α-methyl resonance patterns were in excellent agreement with calculated values based on reactivity ratios of r_A = 0.39 ± 0.06 and r_M = 3.56 ± 0.50 for copolymers prepared in emulsion and on reactivity ratios of r_A = 0.24 ± 0.02 and r_M = 3.21 ± 0.11 for copolymers prepared in solution.     

Role of bulky α-substituent in free-radical polymerization and copolymerization of methyl α-(alkoxymethyl)acrylates

Methyl α-(alkoxymethyl)acrylates were prepared from methyl α-(bromomethyl)acrylate in 80–90% yield. The monomers homopolymerize fast to yield low-molecular-weight polymers. The monomers bearing a linear alkoxymethyl group except for the ethoxymethyl group are characterized by a relatively low ceiling temperature. The rate constants for propagation k_p and termination k_t of methyl α-(butoxymethyl)acrylate were evaluated to be k_p = 298 dm³ · mol^?1 · s^?1 and k_t = 8 · 10⁶ dm³ · mol^?1 · s^?1 at 60°C, respectively. The α-(alkoxymethyl)acrylates are more reactive than methyl methacrylate toward polystyrene radical, except for the α-(dodecyloxymethyl)acrylate which is slightly less reactive, indicating that an increase in the reactivity by the electron-withdrawing character of the alkoxy group prevails over the steric hindrance against addition of the polymer radical, except for the large dodecyloxymethyl group.     

Rate constants for elementary reactions of the radical polymerization of methyl 2-(benzyloxymethyl)acrylate as polymerizable acrylate bearing large substitutents

Methyl 2-(benzyloxymethyl)acrylate (MBZMA) which was synthesized by reaction of methyl 2-(bromomethyl)acrylate with benzyl alcohol was radically homo- and copolymerized. MBZMA polymerized as fast as methyl methacrylate despite of the presence of a large 2-substituent. The absolute rate constants for propagation and termination were evaluated from the direct determination of the steady state concentration of the propagating radical by electron spin resonance spectroscopy at 60°C: k_p = 182 dm³ · mol^?1 · s^?1 and k_t = 1,6 · 10⁶ dm³ · mol^?1 · s^?1. It was deduced from the magnitude of the rate constants that the balance of the slow propagation and termination allows the formation of a polymer. Evaluation of the cross-propagation rate constants in the copolymerization with styrene revealed that primarily the steric effect of the benzyloxymethyl group reduced the reactivity of the polymer radical and that the electronwithdrawing character of the 2-substituent prevailing the steric effect enhanced the monomer reactivity toward the polystyrene radical.     

Determination of the transfer constant of α-thioglycerol in methyl methacrylate free-radical polymerization

Using the Mayo and the Clay-Gilbert method, the transfer rate coefficient of α-thioglycerol (TG) was determined at 50°C for the polymerization of methyl methacrylate (MMA) in a 3 mol · L^?1 tetrahydrofuran solution using different amounts of 2,2′-azoisobutyronitrile (AIBN) as initiator. The transfer rate coefficient was found to be independent of the initiator concentration and higher by a factor of 1.6 when obtained according to the Clay-Gilbert method compared to the Mayo method.     

Synthesis and ring-opening polymerization of α-chloromethyl-α-methyl-β-propiolactone

α-Chloromethyl-α-methyl-β-propiolactone (CMMPL) was synthesized by dehydrohalogenation of α,α-dichloromethyl-β-propionic acid which was obtained by chlorination of α,α-hydroxymethyl-β-propionic acid (DMPA). Due to high strain of the four-numbered ring, CMMPL can be polymerized by ring-opening with or without an initiator. Both electrophiles like trifluoroacetic acid (TFAA) and nucleophiles like triethylamine (TEA) and pyridine, as well as organometallic compounds such as stannous octoate [Sn(Oct)₂)], aluminium triisopropoxide [Al(OⁱPr)₃] and tetrabutyl orthotitanate [Ti(OC₄H₉)₄], were found to be effective initiators. The polymerization can be conducted by either solution or bulk polymerization. P(CMMPL) is insoluble in almost all organic solvents at room temperature. An endothermic peak (ca. 214 ˜ 250°C) attributed to the melting transition of P(CMMPL) was observed in DSC curves. P(CMMPL) tends to have high crystallinity (40% ˜ 60%) as demonstrated by its X-ray diffraction patterns, and the crystallinity was found to vary with the types of initiator used.     

Radical terpolymerization of dodecyl vinyl ether,fumaronitrile and β-chloroethyl acrylate

The radical terpolymerization of dodecyl vinyl ether (DVE), fumaronitrile (FN) and β-chloroethyl acrylate (CEA) were studied. The following results were obtained: (1) The composition ratios of a donor type monomer (DVE) and an acceptor type monomer (FN) in the terpolymers are always constant and equal to unity regardless of the monomer feed ratios; (2) An amount of CEA as the third component is incorporated in the terpolymer. These results cannot be applied in the usual theoretical treatment of the terpolymerization. In the application, there were the contradictions in which the monomer reactivity ratios R₁ and R₂ depend upon the monomer feed ratios and the theoretical calculated compositions of terpolymers are not always consistent with the experimental one, especially when the experiments were carried out at extreme monomer feed ratios. Therefore, the terpolymerization containing the alternating copolymerizing monomer pair of VDE and FN was considered to be different from the terpolymerization of the usual vinyl compounds and the interaction between DVE and FN might participate in their polymerization. Besides, copolymerizations of DVE with FN, CEA with DVE and CEA with FN were studied.     

Radical ring-opening polymerization behavior of ethyl 1-substituted 2-vinylcyclopropanecarboxylate

Ethyl 1-substituted 2-vinylcyclopropanecarboxylate derivatives (VCPs) were prepared from butadiene and the corresponding substituted diazoacetate in the presence of rhodium diacetate as a catalyst. The polymerization behavior of the obtained monomers was investigated revealing that VCPs undergo radical ring-opening polymerization to form poly(1-alkyl-1-ethoxycarbonyl-3-pentenylene)s and that there is a marked influence of the 1-substituent of VCPs on the polymerization rate. The reaction of VCPs with thiophenol was also carried out as a model reaction of their polymerization.     

Kinetic determination of stereoselectivity in the anionic polymerization of α-ethyl-α-phenyl-β-propiolactone

The kinetics of the anionic polymerization of optically active α-ethyl-α-phenyl-β-propiolactone (optical purity 16,8%) initiated with bis(triphenylphosphine)iminium acetate was investigated and the rate constants for the homo-(k_ph) and crosspropagation (k_pc) (considering R and S enantiomers as comonomers) were determined. The knowledge of the values of k_ph and k_pc, equal to 1,53·10^?4 and 9,0·10^?51· mol^?1·s^?1, respectively (25°C, CH₂Cl₂ solvent), allowed us to calculate the distribution of homosequences in the polymer prepared from racemic monomer. The concentration of homosequences was slightly higher than calculated for the process with random enchainment of enantiomers. Thus, the content of homodyads, homotriads, and homotetrads equals 63, 40, and 25%, whereas for the random process it was 50, 25, and 13%, respectively. This difference is, however, too small to create homoblocks which could be responsible for the observed crystallinity of these polymers.     

β‐Nitrostyrene Derivatives as Inhibitors of the Free Radical Polymerization

The free radical polymerization of vinyl monomers is efficiently inhibited by β‐nitrostyrene derivatives. The high reactivity of the growing radicals towards the β‐nitro compounds is controlled by the electron‐donor character of the macroradical and the electron deficiency of the double bond of the β‐nitro derivative. Electron withdrawing substituents at the 4‐position of β‐nitrostyrene increase markedly the inhibition rate. The inhibition efficiency of β‐nitrostyrenes towards electron deficient monomer double bonds is strongly reduced. Polymerization rates and ¹H NMR results show that the β‐nitrostyrene derivatives act as strong inhibitors of the polymerization through a mechanism that involves the release of NO₂.     

Anionic polymerization of β-nitrostyrenes

The rate of polymerization of β-nitrostyrene initiated by sodium alkoxide was setudied gravimetrically. The rate was found to be first order with respect to monomer concentration and first order with respect to initiator concentration. Rate constants in the order of 0,25 dm³ · mol^?1 · s^?1 were obtained at 15°C, 20°C, and 25°C for the polymerization of β-nitrostyrene, p-methoxy-β-nitrostyrene, and p-methyl-β-nitrostyrene initiated by sodium methoxide and by sodium ethoxide. The activation energy of polymerizations initiated by sodium methoxide and by sodium ethoxide was ～24 kJ · mol^?1 and ～ 16 kJ · mol^?1, respectively. The number average degree of polymerization of poly(β-nitrostyrene)s was determined by polymerization of the monomer in the pressence of ¹⁴C-alkanol. This is the first time that accurate number average molar masses of poly(β-nitrostyrene)s have been reported since conventional methods of molar mass determination cannot be used owing to the insolubility of these polymers in most common organic solvents.     

Asymmetric-induction polymerization of β-vinylacrylates

Optically active polymers of methyl, ethyl, n-butyl, and tert-butyl β-vinylacrylates were synthesized by using optically active catalyst systems such as n-BuLi/sodium l-menthoxide and n-BuLi/sodium d-bornoxide. The optically active alkoxides were found to be even more efficient cocatalysts for the asymmetric-induced polymerization than were the corresponding ethers. The polymers obtained were characterized from their optical rotatory dispersion curves and infrared absorption spectra.     

Synthesis and polymerization of fluorinated acrylic monomers substituted in α-position, 2. Synthesis and polymerization of 2-perfluorohexylethyl α-acetoxyacrylate

The synthesis of 2-perfluorohexylethyl α-acetoxyacrylate (^b) H₂C?C(OAc)CO₂C₂H₄C₆F₁₃ ( 1 ) was performed in two steps starting from pyruvic acid and 2-perfluorohexylethanol (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol) with an overall yield of about 50%. Esterification of pyruvic acid with the adequate fluorinated alcohol was followed by enol acetylation to give monomer 1 . Homopolymerization and copolymerization of 1 are easily carried out. From the kinetic study of the homopolymerization and copolymerization of 1 with styrene, the numerical values of the ratio square of the rate constant of propagation over the rate constant of termination k/k_t and of the copolymerization reactivity ratios r₁ and r₂ of the two monomers were determined.     

Polymeric chiral crown ethers, 7. Synthesis of polymers incorporating methyl glycosides of α-D-altrose, α-D-galactose, α-D-glucose and α-D-mannose residues via copolymerization of divinyl ethers

Polymers with chiral asymmetric crown ether units ( 5, 6, 7 and 8 ) were synthesized via cationic cyclopolymerization of methyl 2,3-bis{O-[2-(2-vinyloxyethoxy)ethyl]}-4,6-O-benzylidene α-D -altro-, α-D -galacto-, α-D -gluco- and α-D -manhopyranosides ( 1, 2, 3 and 4 ), respectively. The enantioselective transport of the methyl ester of phenylglycine (PhGlyOCH₃) and phenylalanine (PhAlaOCH₃) was examined through a bulk chloroform solution of chiral polymers from one aqueous solution to another. The transport rate of PhAlaOCH₃ was larger than that of PhGlyOCH₃ for every host polymer. For polymer 7 , the optical purity of PhAlaOCH₃ transported from one to the other phase was 12,6%, and the ratio of rate constants for the faster moving enantiomer A and the slower moving enantiomer B (k_A^*/k_B^*) was 1,48. The faster moving enantiomer was the L -isomer except for the systems polymer 7 ? PhAlaOCH₃ and polymer 8 ? PhAlaOCH₃. This enantioselectivity is caused by the diastereotopic faces of the crown ether units in the host polymers.     

Electric field effects in the polymerization of α-methylstyrene

We here report the boron trifluoride diethyletherate initiated polymerization of χ-methylstyrene in 1,2-dichloroethane. With platinum foil electrodes and an applied electric field of 1–3kV/cm, the initial rate of disappearance of monomer is the same in the absence or presence of the electric field. The rate of formation of polymer at high conversions, however, decreases when the electric field is imposed. The NMR, UV absorption, and fluorescence spectra of the polymers are affected by the field, whereas the IR, ESCA spectra, and melting point of the polymer are unaffected by the field. To probe the reasons for these field effects, we obtained oxidation and reduction potentials of monomer, solvent, and initiator by polarographic or cyclic voltammetric methods. All the components of the system were easily reduced or oxidized. Also, when the anode and cathode were separated by a sintered glass disk, the amount of polymer formed in the anode compartment was greater than that in the cathode compartment. These results suggest that the observed electric field effects are due to electrochemical reactions rather than to the second Wien effect.