Polymerization of alkyl (meth)acrylates in the presence of p-quinones

Russian Chemical Bulletin - The azobisisobutyronitrile-initiated polymerization of methyl methacrylate, butyl methacrylate, and butyl acrylate at 60 °C in the presence of p-quinones differing...     

Photopolymerization of acrylates in the presence of bipyridinium salts

The photopolymerization of acrylic monomers initiated by bipyridinium salts has been studied. It has been shown that active radicals are produced more efficiently in the presence of atmospheric oxygen than in vacuum. A scheme of the process including one-electron transfer involving oxygen has been proposed.     

Cross-linking radical polymerization of di(meth)acrylates in the presence of cobalt(II) porphyrin

The influence of small additives of cobalt(II) porphyrin (Co^IIPn) on cross-linking radical polymerization of butane-1,4-diol dimethacrylate and its structural analog butane-1,4-diol diacrylate was studied. The kinetics of cross-linking radical polymerization of di(meth)acrylates in the absence and presence of Co^IIPn and the diffusional sorption and physical mechanical properties of the resulting polymers were studied. Cobalt(II) porphyrin decreases substantially the polymerization rate and partially suppresses the gel effect. Diacrylate polymerization in the presence of Co^IIPn proceeds with an induction period, whose value is determined by the content of Co^IIPn. Cobalt(II) porphyrin modifies the structure and properties of the formed cross-linked polymers. In the case of dimethacrylate, this is caused by the catalytic chain transfer reaction, whereas for diacrylate the reason is the reversible inhibition reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 807–816, May, 2006.     

Polymerization of carboxyl-containing bicyclic (meth)acrylates

Radical polymerization of 5-carboxybicyclo[2.2.1]hept-2-yl acrylate and 5-carboxy-5-methylbicyclo[2.2.1]hept-2-yl methacrylate in the presence of various initiators was studied. Di-tert-butyl peroxide radical initiator showed high performance in the process and ensured the maximal yield of the polymers. The polymers can be used as film-forming agents.     

Polymerization of (meth)acrylates with aluminum-based initiators

<正>A simple and effective way to prepare poly(acrylate)s,such as poly(methacrylate),poly(butyl acrylate) and poly(butyl methacrylate),has been achieved by using the single component aluminum-based compounds,such as modified methylaluminoxane(MMAO),triisobutylaluminium(TIBA) and triethylaluminium(TEA) as initiators.Effective initiations and high molecular weight polymers with unimodal molecular weight distributions could be easily obtained by varying the reaction parameters of systems under mild conditions.Although these aluminum compounds were inefficient initiators for methyl methacrylate(MMA) polymerization,they exhibited remarkable catalytic activity for butyl methacrylate(BMA) polymerization,affording high molecular weight poly(BMA)s.     

Recent achievements in anionic polymerization of (meth)acrylates

The constant progress of the anionic polymerization of (meth)acrylates is discussed from both the fundamental and practical points of view. A special attention is paid to the improved macromolecular engineering of (meth)acrylate‐based (co)polymers. The resulting most important materials and the scaling‐up process needed for their production are also emphasized. The recent developments witness for the healthy state of the anionic polymerization of these polar monomers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1–10, 1999     

Poly(meth)acrylates Obtained by Cascade Reaction

Preparation, purification, and stabilization of functional (meth)acrylates with a high dipole moment are complex, laborious, and expensive processes. In order to avoid purification and stabilization of the highly reactive functional monomers, a concept of cascade reactions was developed comprising enzymatic monomer synthesis and radical polymerization. Transacylation of methyl acrylate (MA) and methyl methacrylate (MMA) with different functional alcohols, diols, and triols (1,2,6‐hexanetriol and glycerol) in the presence of Novozyme 435 led to functional (meth)acrylates. After the removal of the enzyme by means of filtration, removal of excess (meth)acrylate and/or addition of a new monomer, e.g., 2‐hydroxyethyl (meth)acrylate the (co)polymerization via free radical (FRP) or nitroxide mediated radical polymerization (NMP) resulted in poly[(meth)acrylate]s with predefined functionalities. Hydrophilic, hydrophobic as well as ionic repeating units were assembled within the copolymer. The transacylation of MA and MMA with diols and triols carried out under mild conditions is an easy and rapid process and is suitable for the preparation of sensitive monomers.

     

Interchain exchange in the anionic polymerization of hydroxyalkyl (meth) acrylates

The kinetics of chain propagation and interchain exchange reactions in the anionic polymerization of 2-hydroxyethyl acrylate initiated by lithium tert-butylate were compared. The kinetic parameters of the reactions under consideration were determined. An abnormal ratio between the activation energies of chain propagation and interchain exchange was revealed and explained by the involvement of hydroxyl groups in changes of reactivities of double bonds and ester groups of the initial monomer, the resulting polymer, and the growing active centers of polymerization. The effect of self-inhibition of polymerization was observed and attributed to the fact that ethylene glycol and its alkoxy alcoholate occurring as H-bonded cyclic complexes form at the beginning of the reaction.     

Photopolymerization kinetics of ionic liquid monomers derived from the neutralization reaction between trialkylamines and acid‐containing (meth)acrylates

Polymerizable ionic liquids were synthesized from the neutralization reaction between trialkylamines (tributylamine, trihexylamine, trioctylamine, 2‐(dimethyl‐amino)ethyl acrylate, and 2‐(dimethylamino)ethyl methacrylate) and acid‐containing (meth)acrylates to study the kinetics of their photopolymerization. The ionic liquids formed from acrylic acid and methacrylic acid with trialkylamines showed low or moderate increases in rate compared to their monofunctional analogues. The ionic liquids formed from (meth)acrylic acid and a tertiary amine with a pendant acrylate exhibited rates typical of traditional di(meth)acrylates, although the (meth)acrylates were not covalently attached to the same molecule. All of the phosphate‐based ionic liquids exhibited very rapid polymerization rates and strong dependence on the initial viscosity. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3009–3021, 2007     

Photopolymerization mechanisms of acrylates in poly(methyl methacrylate) films

Photoinitiation processes for photopolymer coating layers have been investigated with respect to quenching rates by a laser flash photolysis using a total reflection cell, as well as to the decomposition‐quantum yield of a sensitizer dye and a radical‐generating reagent by a gel permeative chromatographic analysis (GPC); the sensitizer dye,2‐[p‐(diethylamino)styryl]naphtho[1,2‐d]‐thiazole (DNT) and the radical‐generating reagent, 2,2′‐bis(2‐chlorophenyl)‐4,4′,5,5′‐tetraphenyl‐1,1′‐bi‐1H‐imidazole (BI). From experiments using flash photolysis, strong fluorescence was observed at excitation of 355 nm laser pulse, though no transient absorption was observed. The fluorescence was statically quenched by BI with a quenching distance, R = 11 Å. From the experiments using GPC, the high‐quantum yield of decomposition (Φ) was obtained as Φ (DNT) = 3 and Φ (BI) = 9 for DNT and BI in the presence of acrylate monomers, trimethyrolpropanetri‐acrylate (TMPTA), at 488 nm exposure of 3.36 mJ cm which was required to form a photo‐hardened image, however no decomposition of DNT and BI was detected in the absence of TMPTA. The results imply that the photoinitiator system undergoes efficient static‐dye sensitization and efficient polymerization of the acrylate monomers accompanied with the chain decomposition of DNT and BI. Copyright © 1999 John Wiley & Sons, Ltd.     

Specific features of nickel-catalyzed synthesis of poly(butyl (meth)acrylates)

The activity of the catalytic system NiBr₂(PPh₃)₂/Zn/PhI in polymerization of butyl acrylate and butyl methacrylate and in copolymerization of butyl methacrylate with styrene was examined.     

EPR study of the atom transfer radical polymerization (ATRP) of (meth)acrylates

Electron paramagnetic resonance (EPR) spectroscopy was applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and methyl acrylate (MA) in order to investigate the mechanism of the controlled/“living” radical polymerization system. Although initially only copper(I) species was added to the system as a catalyst, EPR signals of copper(II) species were observed during the polymerization of MMA initiated by ethyl 2-bromoisobutyrate and p-methylbenzenesulfonyl chloride, and polymerization of MA initiated by methyl 2-bromopropionate. As the polymerization proceeded, the concentration of copper(II) increased gradually until a steady state was reached. The EPR results indicate that 5–6% of copper(I) species converted to copper(II) species in polymerization of MMA and about 3% in polymerization of MA at 90°C.     

Synthesis of 5-methyl-5-octyloxycarbonylnorborn-2-yl (meth)acrylates

[4+2]-Cycloaddition of cyclopentadiene to octyl methacrylate with dicyclopentadiene used as starting compound, and also thermal and catalytic addition of (meth)acrylic acids to 5-methyl-5-octyloxycarbonylnorborn-2-ene in the presence of a catalyst, BF₃O(C₂H₅)₂, were studied. 5-Methyl-5-octyloxycarbonylnorborn-2-yl (meth) acrylates, new monomers for polymer synthesis, were prepared.     

New initiator system for the anionic polymerization of (meth)acrylates in toluene. IV. Random copolymerization of (meth)acrylates in toluene initiated by s-BuLi ligated by lithium silanolates

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initiated in toluene by a mixed complex of lithium silanolate  (s-BuMe₂SiOLi) and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with hexamethylcyclotrisiloxane (D₃). Fully acrylate and methacrylate copolymers, i.e., poly(methyl acrylate-co-n-butyl acrylate), poly(methyl methacrylate-co-ethyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methacrylate) of a rather narrow molecular weight distribution have been synthesized. However, copolymerization of alkyl acrylate and methyl methacrylate pairs has completely failed, leading to the selective formation of homopoly(acrylate). As result of the isotactic stereoregulation of the alkyl methacrylate polymerization by the s-BuLi/s-BuMe₂SiOLi initiator, highly isotactic random and block copolymers of (alkyl) methacrylates have been prepared and their thermal behavior analyzed. The structure of isotactic poly(ethyl methacrylate-co-methyl methacrylate) copolymers has been analyzed in more detail by Nuclear Magnetic Resonance (NMR). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2525–2535, 1999     

Syntheses and polymerization of (meth)acrylates containing spiro ortho ester moieties

Acrylates and methacrylates bearing pendant spiro ortho ester groups ( 3 ) were prepared by the reaction of (meth)acrylic acid with bromomethyl spiro ortho esters ( 2 ) in the presence of 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU). These monomers were copolymerized with styrene (St) at 60°C in the presence of α,α'-azobisisobutyronitrile (AIBN) to give the corresponding copolymers with M?_n 6000-17000 and their compositions were in proportion to the feed ratios. Similarly, the copolymerization of 3 with acrylonitrile (AN) was carried out at 60°C to obtain the corresponding copolymers with the similar compositions to the feed ratios. Two kinds of 3 -St copolymers with different compositions were treated with BF₃OEt₂ in refluxing methylene dichloride affording the crosslinked polymers quantitatively. Slight expansion in volume was observed during the crosslinking.     

The role of association/complexation equilibria in the anionic polymerization of (meth)acrylates

The kinetics of the anionic polymerization of methacrylates and acrylates in THF as well as the MWD of the polymers formed depend on the concentration of active centres and of additives, such as lithium halides and lithium alkoxides. These results are discussed on basis of multiple equilibria between non-associated, associated, and complexed ion pairs which are supported by viscosity measurements. The position of these equilibria determines the rate of polymerization, whereas the dynamics of interconversion determine the polydispersity. In the absence of additives the rate of monomer addition to non-associated ion pairs competes with the rate of association. Addition of lithium chloride mainly affects the rate of interconversion between dormant and active species, whereas lithium tert-butoxide forms adducts which stabilize the active centre.     

Synthesis of halomethyl-substituted bicyclo[2.2.1]hept-2-yl(meth)acrylates

Russian Journal of Applied Chemistry - Bicyclic esters, which are reactive monomers for the synthesis of new polymeric products and also of organic compounds, were synthesized by the reaction of...     

Mechanism of anionic polymerization of (meth)acrylates in the presence of aluminium alkyls, 2. Kinetic investigations with methyl methacrylate in toluene

The kinetics of the polymerization of methyl methacrylate initiated by lithium alkyls (tert-butyllithium or ethyl α-lithiobutyrate) was investigated in the presence of aluminium alkyls (triethylaluminium or triisobutylaluminium) in toluene at −78°C. The rate of polymerization decreases considerably once the living dimer is formed. This suggests that the aluminate end-group coordinates with the penultimate ester group of the polymer chain, thus decreasing reactivity. The results are at variance with an activated monomer mechanism.     

Ligated anionic polymerization: An innovative elf-atochem technology for the polymerization of (meth)acrylates

Admittedly performing materials, (meth)acrylic polymers, used in a wide variety of applications, are traditionally produced by radical polymerization processes. The extension of living polymerization, originally developed for dienes and vinyl-aromatics, to (meth)acrylic polymers, would be an interesting opening to a variety of products with a large scope of properties and applications. However, this method suffers from chemical and technical limitations when applied to (meth)acrylates under the usual conditions of solvent and temperature. We report how alkoxy alkoxides-based systems combined with a recent Elf Atochem process offer attractive conditions for ultra-fast anionic polymerization of (meth)acrylates at high solid content. Applications to cost effective syndiotactic poly(methyl methacrylate) and block copolymers syntheses are described.     

Radical copolymerization of alkyl cyclobutenecarboxylates fused with cycloaliphatic framework with alkyl (meth)acrylates

Radical copolymerization behavior of alkyl cyclobutenecarboxylate‐derivatives 4‐6 and related norbornene‐derived compounds 7–9 is described. A variety of alkyl cyclobutenecarboxylates fused with cycloaliphatic framework ( 4–6 ) were prepared by [2 + 2] cycloaddition of five, six, and eight‐membered cycloolefins with alkyl propiolates [alkyl = Me, 2‐hydroxyethyl, and 3‐γ‐butyrolactonyl (γ‐BL)]. The fused cyclobutenecarboxylates 4–6 were radically copolymerized with n‐butyl acrylate (nBA) to afford random copolymers, and terpolymerized with alkyl methacrylates with bulky ester groups [alkyl = γ‐BL and 3‐(3‐methyladamantyl)]. The cyclobutane‐containing bicyclic framework incorporated in the resulting polymer backbone contributes to raising T_g of resulting copolymers. Similar results were obtained when a mixture of related norbornene‐derived compounds were used as monomers with an apparently enhanced T_g‐raising effect in the copolymerization with nBA. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2716–2724