Mechanism Of Polymerization Reaction Research Articles

Direct ethoxylation of fatty methyl ester over Al‐Mg composite oxide catalyst

AbstractFor the purpose of estimating the reaction mechanism of the direct ethoxylation of a fatty ester in the presence of an Al‐Mg composite oxide catalyst, a labeled fatty methyl ester C11H23CO18OCH3 containing 18O isotope was synthesized and directly ethoxylated. The product was evaluated by gas chromatography‐mass spectrometry (GC‐MS). The GC‐MS spectra showed that the 18O isotope label was present only in the methoxy group at the molecular end of the ethoxylated fatty methyl ester. This supports the reaction mechanism of coordination anionic polymerization where the bond between the acyl and methoxy groups of the fatty methyl ester molecule was broken, caused by the bifunctional effect of the acid‐base active sites; an intermediate chemisorption species was formed; and then ethylene oxide was addition‐polymerized sequentially, in parallel.

Functionalized Poly-Imide–Amides: Molten State Reaction Mechanisms and Kinetics

Molten state polymerization reaction mechanisms and kinetics of telechelic polyimide–amides (PIA) were investigated. We conducted a basic study of the reactions of these functionalized systems as a function of the chemical structure of the polymer. Since reaction products very rapidly became insoluble, the study was carried out on model compounds characteristic of reactive chain ends. The data obtained were applied to the study of industrial prepolymers. Different model compounds were synthesized and studied in the temperature range of 100 to 300 °C using such physicochemical methods as HPLC, 1H and 13C NMR (liquid and solid), FTIR and DSC. We were thus able to determine a number of precise parameters characteristic of the different reactions occurring (isomerization, crosslinking, co-reactions and side reactions). The results were applied to the study of 1500 molecular weight prepolymers and preimpregnated carbon fibres.

Fundamentals of plasma chemistry and its application to drug engineering

In this review, our novel research works in both low temperature plasma chemistry and solid state plasma chemistry were described. As for low temperature plasma, the ESR study on plasma-induced radicals of several selected conventional polymers was shown including the detailed analyses of the radical structure and the mechanism by which the radicals were formed on typical degradable methacrylic polymers and cross-linkable polystyrene. One of the pharmaceutical applications of the plasma processing for drug delivery system (DDS) was also described, which includes the preparations of double-compressed tablet consisting of drugs as a core material and various types of polymers as a wall material followed by plasma-irradiation on such a tablet. As for solid state plasma, the detailed reaction mechanism of solid state mechanochemical polymerization was shown including the solid state single electron transfer and the special feature of the resulting polymers. The structural criteria for polymerizable monomer derived from the quantum chemical considerations were also established. Based on the above findings, we synthesized various polymeric prodrugs by mechanochemical polymerization and studied the nature of hydrolyses (drug release).

Photopolymerization of Styrene and Methyl Methacrylate with Poiy(methylphenylsilane) as Photoinitiator

AbstractThe rate of photochemical polymerization of styrenc (St) and methyl methacrylate (MMA) with polymcthylphenylsilane (PMPS) as initiator were measured. Polymethylphenylsilane is photodegraded to form silyl radicals that may initiate polymerization of St and MMA. The kinetic orders of polymerization reactions of initiator PMPS in St and in MMA systems are 0.49 and 0.29, respectively. The rate coefficients kp and kt are 38.1 and 0.71 × 107 Lmol‐−1s−1 in the St/PMPS system and 249.5 and 6.71 × 107 Lmol−1s−1 in the MMA/PMPS system. A polymerization reaction mechanism is proposed.

Direct Kinetic Measurements of Vinyl Polymerization on Metal and Silicon Surfaces Using Real-Time FT-IR Spectroscopy

A real-time FT-IR (RT/FT-IR) technique has been used to perform direct kinetic measurements of vinyl polymerization on metal and silicon surfaces. Here, we are reporting our results in studies of anaerobic and photo-induced anionic polymerizations of monomers containing vinyl functional groups (>C=C<) for adhesive and coating applications. For anaerobic polymerization we are investigating the hydroperoxide-initiated free radical polymerization of model multifunctional methacrylate monomer systems. We will report the results of our studies on the catalytic effects of different dithiolate complexes and related accelerators. In photo-induced anionic polymerization we will report our studies for ethyl cyanoacrylate (CA) polymerization initiated by a controlled release of anion from a stable chromium complex precursor ( trans-Cr-(NH3)2(NCS)4−K+). Because of high surface sensitivity of the CA monomer, the polymerization kinetic studies were performed on a clean silicon surface at room temperature. The effect of the initiator concentration and irradiation wavelengths on polymerization kinetic rate will be discussed. The acrylic polymerization was monitored with the use of the C=C stretching band at 1634 and 1627 cm−1 for polyglycol dimethacrylate and cyanoacrylate, respectively. Both the degree of polymerization and the intrinsic rates of the polymerization reactions were calculated for kinetic comparisons. For anaerobic polymerization studies, GC/FT-IR software was used which provided a real-time screen display of IR spectral changes as the reaction proceeded. For very fast cyanoacrylate anionic polymerization studies, new FT-IR kinetic software was used to collect 204 spectra per minute with one spectrum per scan. In this case, the interferograms were collected first; post-Fourier transform conversion and spectral script reduction were then performed. Some detailed experimental techniques and polymerization reaction mechanisms will also be discussed.

The properties of polymer protective coatings of optical fibers. I. The influence of active diluent concentration on the properties of UV‐cured epoxyacrylate coatings

AbstractThe strong relationship between the properties of UV‐cured epoxyacrylate coatings of optical fibers and their compositions was found. The epoxyacrylate oligomer‐to‐acrylate monomer active diluent ratio was used to give a simple explanation of the mechanism of polymerization reaction of UV‐curable epoxyacrylate compositions. © 1993 John Wiley & Sons, Inc.

Mössbauer effect study of polymerization reaction mechanisms with tin compounds as catalysts

Polymerization of hexachlorocyclophosphazene in the presence of tetraphenyltin has been studied. The process of phenylation of propagating macroradicals with simultaneous chlorination of tetraphenyltin was established using Mössbauer spectroscopy as well IR- and NMR-spectroscopy. The possibility to regulate molecular mass and yield of polydichlorophosphazene is shown.

Studies on the Polymerization of Vinyl Toluene in Microemulsion Medium

Oil in water, vinyltoluene - SDS - water - n-pentanol microemulsions are prepared and used to study the kinetics and mechanism of polymerization reactions of vinyltoluene. Initiations are effected by using both potassium peroxodisulphate (KPS), a hydrophilic and 2,2' azobisicobutyronitrile (AIBN), a hydrophobic initiator separately. At the end of polymerization, stable polymer microlatexes are obtained. The viscosity average molecular weights M v ) range from 1.5 to 3.2 × 10 6 . The R p and M v show fractional and negative order dependence on initiator concentration respectively, but vary directly with monomer concentration. The overall activation energy of polymerization (20.4 kcal/mol) agrees with that for homogeneous vinyl polymerization.

Kinetic studies of photopolymerization using real time FT‐IR spectroscopy

AbstractThe real time FT‐IR (RT/FT‐IR) technique has been recognized as a very vital tool to quantitatively study the curing parameters such as the effects of initiator (or catalyst) type and concentration, accelerator, stabilizer, irradiation wavelength, temperature, and curing environments. Herein, our results in studies of photoinduced polymerizations for adhesive and coating applications are reported. The photoinduced polymerizations studied included anionic and hydrosilation (a polyaddition polymerization) reactions. In photoinduced anionic polymerization our studies for ethyl cyanoacrylate polymerization are described. The effect of the concentration of photoinitiator and inhibitor on the ethyl cyanoacrylate polymerization kinetic rate will be discussed. In photoinduced catalytic hydrosilation reaction studies, the effects of the catalyst concentration and staging irradiation are disclosed. The hydrosilation reaction was monitored using a SiH silicone hydride stretching band located at 2169 cm−1. The cyanoacrylate polymerization was monitored using the CC stretching band occurring at 1617 cm−1. The hydrosilation conversion was completed with an appropriate formulation. For monofunctional cyanoacrylate monomer, the photoinduced conversion to straight chain polymer was approximately 85% for a 60 s period. The intrinsic rates of the reactions were calculated for kinetic comparisons. For very fast cyanoacrylate polymerization studies, new FT‐IR kinetic software was used to collect 204 spectra/min. Some detailed experimental techniques and polymerization reaction mechanisms are also discussed. © 1993 John Wiley & Sons, Inc.

Recent Developement of Polymerization Using Transition Metal Complexes as Catalyst

Recent studies on polymerization using transition metal complexes as catalyst are reviewed. Ti, W, and Ru complexes catalyze ring opening metathesis polymerization of cyclic olefins such as norbornene and cyclooctene to give the corresponding polymers. Living polymerization is achieved in many cases. Structures and reactivities of cyclopentadienyl complexes of Ti, Zr, and Hf are investigated in order to elucidate reaction mechanism of olefin polymerization catalyzed by Kaminsky system. Transition metal complex catalyzed synthetic organic reactions such as carbonylation of organic halides, arylation of olefins as well as cross-coupling of Grignard reagents with organic halides have been applied to preparation of various polymers. Coupling reaction of aryl halides promoted by Ni complex is developed to preparation of π-conjugated polymers which show interesting electrical and optical properties.

高分子科学最近の進歩 電解重合の反応メカニズム

高分子科学最近の進歩 電解重合の反応メカニズム

A theoretical investigation of Ziegler-Natta polymerization reaction mechanisms of acetylene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA theoretical investigation of Ziegler-Natta polymerization reaction mechanisms of acetyleneShogo SakaiCite this: J. Phys. Chem. 1991, 95, 18, 7089–7093Publication Date (Print):September 1, 1991Publication History Published online1 May 2002Published inissue 1 September 1991https://doi.org/10.1021/j100171a069RIGHTS & PERMISSIONSArticle Views150Altmetric-Citations31LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (578 KB) Get e-Alerts

Emulsion Polymerization of Chloroprene. Polymerization Mechanism and Evaluation of Crosslinking Density

The polymerization and crosslinking reaction mechanisms were studied for the emulsion polymerization of chloroprene. The dependence of volume of monomer droplet, surface-tension and crosslinking density on conversion was confirmed to be corresponding to the Harkins and Smith-Ewart models. Crosslinking densities were estimated from swelling ratios of the gel polymers prepared at various temperatures in the absence of a chain transfer reagent. The ratios of the rate constant of the propagation to the crosslinking K were calculated to be 2.0×10−4, 7.1×10−4, and 9.9×10−4 at 10, 40, and 55°C, respectively. The difference between activation energies of these two mechanisms was 27.8 kJ mol−1. The proportions of polymer in the growing polymer particles during the existence of monomer droplets θ′ were also caluculated to be 0.47, 0.45, and 0.42, at each temperature.

Plasma polymerization and plasma treatment of polymers. Review

The paper described some current achievements in the field of plasma polymerization and plasma treatment. It is not an exhaustive review of this field but merely reflects present-day interests in and the views of the author on the main results of research work. Many deep and all-sided reviews on the basic phenomena, the theory and reaction mechanisms of plasma processes and plasma polymerization do not figure in this short review, nor does it cover the problems of the formation of diamond-like and amorphous carbon attracting considerable attention in the last few years. The reader may acquiant himself with these aspects through the relevant articles and books. Some aspects of the latest achievements in the precipitation of organic and organometal are examined. The trends in future research and developments in plasma precipitation are briefly discussed.

Heterogeneous radical polymerization: Reactivity and morphology control

AbstractIn the first part of that review, some physical effects are studied, causing changes in the kinetics and mechanism of polymerization reaction when going from an homogeneous solution polymerization to heterogeneous polymerizations. Three main cases are considered: acrylonitrile polymerization in which the polymer is neither soluble nor swollen by its monomer, vinyl chloride polymerization in which the polymer is not soluble in its monomer but is swollen by it, and styrene‐divinylbenzene resin where the apparent reactivity of the second double bond is governed by the syneresis phenomenon. In addition to the Tromsdorff effect on the termination reactions, perturbation due to the heterogeneous character of the reaction may affect the termination reaction by isolating free radicals, propagation reaction by restricting the mobility of the monomer or that of the growing radical through a template effect, or even transfer reactions on the polymer. Via concentration of pendent double bonds are observed inside crosslinked nodules of styrene‐divinylbenzene copolymers.The second part is devoted to the study of morphology. Special emphasis is paid to the case of vinylchloride polymerization where the aggregation phenomena are governed by electrostatic interactions, and also to the case of styrene‐divinylbenzene resins where the formation of the morphology is discussed in terms of critical conversions for phenomena such as appearance of microgels, overlapping of nodules and phase separation. Similarities between porous morphology of PVC and styrene‐divinylbenzene resins are pointed out. Some discussions are also devoted to the supermolecular structures inside small particles in PVC, and also in multistep emulsion copolymerizations.

Poly(alkyl α‐bromoacrylate)s. III. Tacticity analysis from 19 mHz 13C‐NMR spectroscopy

AbstractPolymer tacticity was determined by 19 mHz 13C‐NMR spectroscopy for isotactic, atactic, and syndiotactic samples of six poly(alkyl α‐bromoacrylate)s. Included in this series were the methyl, ethyl, n‐propyl, i‐propyl, n‐butyl, and n‐pentyl esters. Complete assignments for the 10 pentad peaks of the carbonyl carbon resonance were achieved for all but the i‐propyl ester while a complete analysis of tetrad tacticity from the backbone methylene carbon resonance was possible for all but the methyl ester. The tetrad values calculated from the experimentally determined pentad contents were found to agree with the experimental tetrad values. As a result of insufficient peak separation of the quaternary carbon resonance, complete pentad assignments were possible in only a few instances. The polymerization reaction mechanisms were discussed in terms of the propagation statistics calculated from the experimentally determined tetrads and pentads. Both the atactic and syndiotactic polymers that were synthesized by free radical techniques displayed Bernoullian or random statistics while the stereochemical statistics of the isotactic polymers synthesized by a modified Grignard complex were more consistent with nonrandom or first‐order Markovian statistics.

The Mechanisms of the Polymerization Reactions in Diacetylene Crystals: Esr-Analysis of the Paramagnetic Reaction Imtermediates

Abstract The mechanisms of the solid state polymerization reactions in diacetylene crystals have been investigated by ESR-spectroscopy. The electronic structure of the diradical, carbene and dicarbene intermediates of the low-temperature photopolymerization reaction of diacetylene crystals have been analyzed. From the chain-lengths dependent ESR fine structure and from the isotropic hyperfine structure detailed information concerning the radical and carbene wavefunctions were deduced. A multiplicity change from S=1 to S=2 occurs at the hexamer intermediates.

Study of ionic catalytic systems by the electrodialysis method

AbstractA special method of electrodialysis has been developed for investigation of the kinetics and mechanism of polymerization reactions involving ions. The ionic composition of homogeneous systems such as Cp2TiRClAlRCl2, RTiCl3 + AlRCl2, Ti(OR)4 + AlR3, and (RLi)n has been studied. The composition of catalytically active ions has been determined. Using the regularities of “open” systems, the methods of determining the carbocation reactivity under electrodialysis conditions havebeen worked out. The impulse electrodialysis method has been suggested for studying ionic polymerization kinetics and evaluating the rate constants ofion reactions with the monomer and gegenion.

Carbon‐13 NMR spectra and reactivities of vinyl compounds in ionic and radical polymerizations

AbstractThe 13C‐chemical shift of β‐carbon in the vinyl group of monomers was correlated with the relative reactivity of the monomer in the cationic copolymerizations of substituted styrenes, benzyl vinyl ethers, and phenyl vinyl ethers and also in the copolymerization of substituted styrenes by Ziegler catalysts. It was found that the β‐carbon resonates at the higher field, the higher the reactivity of the monomer is. The reverse was the case in the anionic addition reaction of substituted styrene to living polystyrene. The relations were also studied between the 13C‐chemical shift and the e‐value of the monomer and some direct evidence was obtained for the validity of the Q–e scheme. From these results it was revealed that the 13C‐chemical shift of vinyl compounds is an important tool for the examination of the mechanism of polymerization reaction.

Differential method of treating chromatographic curves when analysing polymerization kinetics

A study was made of the treatment of chromatographic curves when analysing polymerization kinetics using PS samples obtained by thermal polymerization in bulk by different methods. The relative error of the method was evaluated. Possibilities offered by the method and advantages were shown when analysing MWD of polymers, in order to study kinetics and the reaction mechanism of polymerization at advanced stages of monomer conversion.