Influence of allyl ethers in coating resins

The effects of allyl ethers in coating resins have been studied in relations to different systems. The details that have been investigated are: the reactions between allyl ethers-styrene-cobalt salt in air, the influence of cobalt salt on oxidized allyl ethers, and the interaction between allyl ethers and maleic esters with respect to copolymerization. The curing rates of allyl functional oligomers as coatings have also been studied. The results are summarized together with the results from a previous article by the same authors to give an overall view of the curing mechanism in allyl ether functional unsaturated polyester resins dissolved in styrene.     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. III. Mathematical model

A mathematical model was developed to aid in the further understanding of the growth of latex particles in the emulsion polymerization of vinyl acctate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40). The model incorporates the main features of the system observed experimentally: copolymerization in the aqueous phase, at the particle surface, and chain transfer to TREM LF-40. The reactions at the particle/water interface and, more specifically, the chain transfer to TREM LF-40 leading to a decrease in the average number of radicals per particle, was found to be the most significant mechanism for explaining the difference in kinetic results found for TREM LF-40 and its nonpolymerizable counterpart. The copolymerization of vinyl acetate with TREM LF-40 was also shown to slow the overall polymerization rate. However, the copolymerization alone was not sufficient to account for the decreased polymerization rates observed experimentally. A combination of copolymerization and chain transfer to TREM LF-40 was found to provide a good fit of the experimental results. © 1993 John Wiley & Sons, Inc.     

Pursuit of reinitiation efficiency of resonance‐stabilized monomeric allyl radical generated via “degradative monomer chain transfer” in allyl polymerization

For a deeper understanding of allyl polymerization mechanism, the reinitiation efficiency of resonance‐stabilized monomeric allyl radical was pursued because in allyl polymerization it is commonly conceived that the monomeric allyl radical generated via the allylic hydrogen abstraction of growing polymer radical from monomer, i.e., “degradative monomer chain transfer,” has much less tendency to initiate a new polymer chain and, therefore, this monomer chain transfer is essentially a termination reaction. Based on the renewed allyl polymerization mechanism in our preceding article, the monomer chain transfer constant in the polymerization of allyl benzoate was estimated to be 2.7 × 10^?2 at 80 °C under the polymerization condition, where the coupling termination reaction of growing polymer radical with allyl radical was negligible and, concurrently, the reinitiation reaction of allyl radical was enhanced significantly. The reinitiation efficiencies of monomeric allyl radical were pursued by the dead‐end polymerizations of allyl benzoate at 80, 105, and 130 °C using a small amount of initiators; they increased remarkably with raised temperature. Thus, the enhanced reinitiation reactivity of allyl radical at an elevated temperature could bias the well‐known degradative monomer chain transfer characteristic of allyl polymerization toward the chain transfer in common vinyl polymerization. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. I. Kinetic studies

A polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) and its nonpolymerizable counterpart were used in comparative studies of the emulsion polymerization of vinyl acetate. The conversion-time behavior differed for the two surfactants; the TREM LF-40 showed a decrease in the polymerization rate with increasing concentration while its hydrogenated derivative showed the opposite behavior, the rate increasing with increasing surfactant. Particle size analysis revealed a decreasing particle size with increasing surfactant concentration for both series of reactions. An explanation for the seemingly ambiguous results obtained for the polymerizable surfactant was sought by examining the reactivity of its vinyl group in copolymerization with vinyl acetate and its allylic group in a chain transfer reaction. The results suggest that both the copolymerization and chain transfer reactions can lead to the observed reduction in polymerization rate with increasing TREM LF-40 concentration. © 1992 John Wiley & Sons, Inc.     

Ethylene polymerization studies with supported cyclopentadienyl,arene, and allyl chromium catalysts

Highly active catalysts for low pressure ethylene polymerization are formed when chromocene, bis (benzene)- or bis (cumene)-chromium or tris- or bis (allyl)-chromium compounds are deposited on high surface area silica-alumina or silica supports. Each catalyst type shows its own unique behavior in preparation, polymerization, activity, isomerization, and response to hydrogen as a chain transfer agent. The arene chromium compounds require an acidic support (silicaalumina) or thermal aging with silica to form a highly active catalyst. At 90°C polymerization temperature arene chromium catalysts produced high molecular weight polyethylene and showed, in contrast to supported chromocene catalysts, a much lower response to hydrogen as a chain transfer agent. An increase in polymerization temperature caused a significant decrease in polymer molecular weight. Addition of cyclopentadiene to supported bis (cumene)-chromium catalyst led to a new catalyst which showed a chain transfer response to hydrogen typical of a supported chromocene catalyst. Polymerization activity with tris- or bis (allyl)-chromium appears to depend on the divalent chromium content in the catalyst. Changes in the silica dehydration temperature of supported allyl chromium catalyst have a significant effect on the resulting polymer molecular weight. High molecular weight polymers were formed with catalysts that were prepared using silica dehydration temperatures below about 400°C. Dimers, trimers, and oligomers of ethylene were usually formed with catalysts that were prepared on silica dehydrated much above 400°C. The order of activity of the different types of catalysts was chromocene/silica > chromocene/silica-alumina > bis (arene)-chromium/silica-alumina ? allyl chromium/silica.     

pH对丙烯酸-丁烯醛共聚合反应的影响

具有功能基的聚合物因其所具备的特殊性能而获得越来越多的应用[1] .带醛基的聚合物可在室温下很容易与酶、抗体、抗原、蛋白质、细胞等含氨基的生物高分子反应 ,生成Ｓｃｈｉｆｆ碱 ,将这些生物高分子共价偶联到聚合物上 ,并能保持它们绝大部分的生物活性 ,因而在免疫分析、生物化学、生物医学等领域有着广泛的应用前景[2～ 4 ] .然而 ,到目前为止 ,带醛基的聚合物的合成研究主要集中在丙烯醛的均聚及共聚反应[5～ 8] ,而对其它不饱和醛的聚合研究报道很少 .但是由于丙烯醛聚合物分子链上相邻的醛基极易形成缩醛或半缩醛而使自由醛基的数量…     

Emulsion polymerization of vinyl acetate using a polymerizable surfactant. II. Polymerization mechanism

The mechanism of growth of latex particles in the emulsion polymerization of vinyl acetate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) was investigated. Both the aqueous phase and the particle/water interface were found to be loci for the copolymerization of TREM LF-40 with vinyl acetate. Competitive growth experiments using TREM LF-40 and its nonpolymerizable derivative were conducted to separate the effects of aqueous phase and particle surface. Particle size analysis of the seeded and unseeded polymerizations coupled with kinetic results suggested that the reactions at the particle/water interface are more important and that the particle size of the latexes is a key parameter controlling the polymerization rate through copolymerization and chain transfer to the polymerizable surfactant at the particle surface. A decrease in particle size lead to an increase in the amount of TREM LF-40 polymerized at the particle surface and to a decrease in polymerization rate. © 1992 John Wiley & Sons, Inc.     

THE EFFECTS OF ALLYL ETHERS UPON RADICAL POLYMERIZATIONS

Three allyl ethers, viz. the ethyl, 2-hydroxyethyl and phenyl compounds, have been examined as additives in radical polymerizations of styrene (STY), methyl methacrylate (MMA) and acrylonitrile (ACN) at 60°C using azobisisobutyronitrile as initiator. As retarders and transfer agents, the ethers are considerably more effective with ACN than with the other monomers. Allyl phenyl ether engages in significant copolymerization with ACN and slight copolymerization with MMA; there is negligible incorporation in polySTY.     

Studies in Vinyl Polymerization. Reinitiation by Allyl Chloride Transfer Radicals in the Polymerization of Vinyl Acetate

The kinetics of vinyl acetate polymerization in the presence of allyl chloride were studied by a dilatometric method. The retardation of the rate of polymerization was explained in terms of degradative chain transfer to allyl chloride. Analysis of the polymerization rate data indicates that a relatively large proportion of the allyl chloride transfer radicals is reactive toward initiation.     

Crosslinking reaction in the cationic polymerization of 1, 3-pentadiene

The cationic polymerization of 1,3-pentadiene (PD) initiated by AlCl_3 in n-hexane was carried out. Effects of arenes, alkyl halides and ethers on the gel formation resulting from crosslinking reaction were investigated. The erosslinking was reduced by various arenes through a chain transfer mechanism. Alkyl halides such as tert-butyl chloride and allyl chloride could complex with AlCl_3 to generate an initiating system giving rise to a gel-free polymerization, while benzyl chloride reduced the formation of gel by chain transfer. Ethers exerted two effects on the polymerization system: giving a complex initiating system with AlCl_3 to produce a relatively high molecular weight polymer, or reducing crosslinking by lowering activity of carbocations.     

Polymerization of diethylene glycol bis(allyl carbonate) by means of di-sec-butyl peroxydicarbonate

The initial stages of the free radical polymerization of diethylene glycol bis(allyl carbonate) at temperatures of 35–65°C have been studied. The polymer is unsaturated and cyclization to give a 16-membered ring occurs only to a small extent. The kinetic order with respect to the initiator, di-sec-butyl peroxydicarbonate, has an average value of 0.79; the order increases slightly with peroxydicarbonate concentration over the range 0.018–0.22M. The molecular weight of the polymer isolated after 3% polymerization is close to 19,000. It shows no significant dependence on initiator concentration or on temperature. The dominant feature of the bulk polymerization, as in free radical polymerization of the other allyl and diallyl monomers, is degradative chain transfer in which the growing polymer radical abstracts a hydrogen atom from a monomer unit to give a relatively unreactive allylic radical. The dependence of rate on initiator concentration is rationalized if some of these allylic radicals are able to reinitiate polymerization. The transfer constant to monomer is 0.014 at 50°C, assuming that the main termination step involves mutual termination of allylic radicals. Carbon tetrachloride is an active transfer agent with a transfer constant of 0.20 ± 0.04 at 50°C. Toluene, which is less active, has a transfer constant of 0.0064 at 50°C and also retards the polymerization. Some kinetic studies have been made with other initiators, including di-2-methyl-pentanoyl peroxide which initiates polymerization at temperatures as low as 13°C.     

Photoinitiated cationic oligomerization of aryl 1-propenyl ethers

A series of aryl 1-propenyl ethers (ArPE) were prepared by the isomerization of the corresponding allyl aryl ethers (AArE) and used for photoinduced cationic polymerization studies. Attempted polymerization reactions using diaryliodonium salts as photoinitiators generally resulted in low yields of oligomers. Further studies revealed that these compounds have much lower reactivity in cationic vinyl polymerization as compared to their alkyl analogues. Moreover, side reactions resulting from chain transfer due to Friedel–Crafts alkylations take place and compete with vinyl polymerization. These side reactions are responsible for the low molecular weights observed in the cationic photopolymerization of aryl 1-propenyl ether monomers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3017–3025, 1999     

Controlled radical copolymerization of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate

Narrow disperse copolymers of N-vinylpyrrolidone with 1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate have been prepared for the first time by reversible addition fragmentation chain transfer pseudo-living radical polymerization in the presence of benzyl dithiobenzoate. The relative activities of the monomers indicating the occurrence of alternating copolymerization have been estimated. The copolymerization of equimolar N-vinylpyrrolidone-1,1,1,3,3,3-hexafluoroisopropyl-α-fluoroacrylate mixtures shows typical features of reversible addition fragmentation chain transfer pseudoliving radical polymerization: deceleration of polymerization compared to the classical radical process, degeneration of the gel effect, successive increase in the number-average molecular mass with conversion, and formation of narrow disperse copolymers.     

Synthesis and polymerization of multiallyl monomer in matrix of poly(methacryloyl chloride)

By reacting poly(methacryloyl chloride) (PMKC) with allyl amine, a multiallyl monomer in PMKC matrix has been obtained. Free-radical polymerization of multiallyl monomer in diluted solutions at a concentration of 12 g/L multiallyl monomer occurs partly along ordered allyl units in the matrix and results in ladder-type branched polymers. The polymers obtained are soluble in alcohols, DMF, DMSO and have unreacted allyl double bonds. The structures of multiallyl monomer and homopolymer have been found on the basis of elemental analysis, IR and ¹H-NMR spectra and an examination of the products of hydrolysis. The effect of the reaction of degradative chain transfer on the structure of the polymer obtained has been discussed.     

Radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene. III. Polymerization mechanism

In the radiation-induced emulsion copolymerization of tetrafluoroethylene with propylene, the dose rate dependence, the effect of emulsifier concentration, and the effect of monomer composition were studied. The rate of polymerization was proportional to the 0.90 power of the dose rate and the 0.26 power of the emulsifier concentration. The degree of polymerization was independent of the dose rate and the emulsifier concentration. Both the rate of polymerization and the degree of polymerization increased with tetrafluoroethylene content in the monomer mixture. The resulting copolymer was an alternating polymer over a wide range of monomer composition. It was concluded from the dose rate dependence of the rate of polymerization that the emulsion copolymerization is mainly terminated by degradative chain transfer of the propagating radical to propylene.     

氢气对氯硅烷功能化非共轭α,ω-双烯烃和丙烯共聚物链结构的影响

基于Ziegler-Natta催化剂的氯硅烷功能化非共轭α,ω-双烯烃与丙烯共聚,在水的引发下脱水缩合可有效地形成长支链结构的聚丙烯树脂.而氢气常作为丙烯聚合中的链转移剂,调控聚丙烯的分子量,基于此,研究了氢气对氯硅烷功能化非共轭α,ω-双烯烃与丙烯共聚物链结构的影响.核磁共振氢谱(~1H-NMR)测试结果表明,氢气抑制了氯硅烷功能化非共轭α,ω-双烯烃的插入,随着氢气用量的增加,共聚物分子链中端基乙烯基含量由0.12 mol%降低到0.05 mol%.熔体流变行为测试结果显示,聚合物熔体的储能模量、损耗模量和零剪切黏度均随着氢气用量增加而降低,这主要是由于相对分子质量减小和长支链密度的减少.     

Note Synthesis and Characterization of Poly-(2-Methallyl-p-cresol)

In spite of the low reactivity of allyl monomers, attempts have been made to prepare polymers by polyrecombination of allyl aromatic compounds. We were encouraged by the stability of allyl radicals [1-8]. The literature on the Claisen rearrangement of polyfunctional allyl aryl ethers contains some observations of the formation of tarry masses and resinification of polyfunctional aryl ethers. Details of the polymerization and the possible structures were not studied. We felt it interesting to synthesize this new monomer, 2-methyallyl-p-cresol, by the rearrangement, and to study in detail the polymerization and characterization of the polymer.     

Bulk polymerization of diallyl benzene-dicarboxylates I. Influence of temperature on allyl group reactivity

The bulk polymerization of the three isomeric diallyl benzene-dicarboxylates was carried out in the temperature range 80–285°C. The progress of the polymerization process was examined by determination of the conversion of allyl groups double bonds. The reactivity of these groups in the polymerization increases in the following order of isomers: ortho < para < meta at 80–230°C. At temperatures above 200°C the thermal polymerization with activation energies for ortho, meta and para isomers 32, 27, and 28 kcal/mol of allyl group, respectively, has been observed. With the increase of temperature from 80 to 230°C for each of the monomers the number of allyl groups consumed when forming one C? C chain (degree of chain polymerization) decreases, but at the same time the kinetic chain length increases several times. The results have been explained by the growing role of chain transfer reactions with simultaneous increase of an ability to reinitiation by occured radicals. The mechanisms of thermal polymerization have been proposed.     

Preparation of poly(methyl methacrylate) and copolymers having enhanced thermal stabilities using sucrose-based comonomers and additives

A series of methyl methacrylate polymers have been prepared containing sucrose-based crosslinkers and additives. Thermogravimetry and long-term aging studies at 200°C show that sucrose-based alkyl and allyl ethers provide unprecedented thermal stability to linear, as well as crosslinked, poly (methyl methacrylate) or PMMA. Linear PMMA and PMMA crosslinked with trimethylolpropane trimethacrylate (TMPTMA) both degrade at 284°C. PMMA containing octa-O-crotylsucrose (1 mol %) degraded at 322°C. Depending on concentration, PMMA containing octa-O-allylsucrose (0.1-1.0 mol % and higher) degraded between 334 and 354°C, and PMMA containing 1′,6,6′-trimethacryloyl-2,3,3′,4,4′-penta-O-methylsucrose (0.1-1.0 mol %) degraded between 309 and 320°C. PMMA containing (1 mol % each) sucrose-based esters, ester-ether derivatives, all degraded at or below the degradation temperature of pure PMMA. Long-term air aging studies revealed that PMMA containing penta-O-methylsucrose trimethacrylate, octa-O-allylsucrose, and octa-O-crotylsucrose did not flow or sag after heating for 24 h at 200°C, but the polymers did show yellowing. While linear and crosslinked samples of PMMA containing compounds other than sucrose ethers lost more than 50% of their original weight within 15 h at 200°C, PMMA containing sucrose-based ethers lost about 8 and 20% of their original weight after 1 and 8.5 days, respectively. Herein we propose a unique mechanism by which saccharide ethers may be imparting this unprecedented thermal stabilization to PMMA. While tertiary hydrogens alpha to oxygens in saccharide ethers are stable to chain transfer during normal polymerization temperatures, they readily chain transfer at 200°C where PMMA is unstable. Chain transfer of these hydrogens is followed by fragmentation to produce alkyl, allyl or crotyl radicals, which combine with the macroradicals and terminate depropagation. © 1995 John Wiley & Sons, Inc.     

Modeling and Experimentation of RAFT Solution Copolymerization of Styrene and Butyl Acrylate,Effect of Chain Transfer Reactions on Polymer Molecular Weight Distribution

Chain transfer reactions widely exist in the free radical polymerization and controlled radical polymerization, which can significantly influence polymer molecular weight and molecular weight distribution. In this work, the chain transfer reactions in modeling the reversible addition–fragmentation transfer (RAFT) solution copolymerization are included and the effects of chain transfer rate constant, monomer concentration, and comonomer ratio on the polymerization kinetics and polymer molecular weight development are investigated. The model is verified with the experimental RAFT solution copolymerization of styrene and butyl acrylate, with good agreements achieved. This work has demonstrated that the chain transfer reactions to monomer and solvent can have significant impacts on the number‐average molecular weight (M_n) and dispersity (Ð).