Novel reaction between cyclic formal and ethylene oxide

Novel reactions between trioxane and ethylene oxide were discovered, and three novel cyclic formals were isolated and identified. These novel cyclic compounds clarified the initiation mechanism of the copolymerization of trioxane and ethylene oxide. This type of reaction was not limited to the reaction between trioxane and ethylene oxide but was also generalized to the reaction between the cyclic formal and ethylene oxide. Although an NMR method for analyzing the ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide has not yet been established, the three newly found novel cyclic compounds, composed of 1 mol of ethylene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane, were useful for analyzing the ethylene oxide sequences. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different ¹H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that had one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the ¹H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequences by the ¹H NMR method for the copolymer from trioxane and ethylene oxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 520–533, 2004     

Analysis of ethylene oxide sequences of the acetal copolymer from trioxane and ethylene oxide

An NMR method for the analysis of the ethylene oxide sequence of the acetal copolymer from trioxane and ethylene oxide has not yet been established. We found three novel cyclic compounds composed of 1 mol of ethyelene oxide and 1 mol of trioxane, 2 mol of ethylene oxide and 1 mol of trioxane, and 3 mol of ethylene oxide and 1 mol of trioxane. These compounds gave only one consecutive oxyethylene unit, two consecutive oxyethylene units, and three consecutive oxyethylene units in three consecutive oxymethylene units, respectively, and gave different ¹H NMR spectra for each oxyethylene unit. Considering these data, we synthesized three polymeric model compounds that have one consecutive oxyethylene sequence, two consecutive oxyethylene sequences, and three consecutive oxyethylene sequences in an oxymethylene main chain. By a linear combination of the ¹H NMR spectrum of each oxyethylene unit of the three polymeric model compounds, we succeeded in determining the ethylene oxide sequence by the ¹H NMR method for the copolymer from trioxane and ethylene oxide. Good agreement was observed between the ¹H NMR method and the hydrolysis method for the analysis of the ethylene oxide sequences. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3239–3245, 2001     

Radiation-induced postpolymerization of trioxane in the solid state. V. Studies on copolymer composition

Studies on the composition of copolymers obtained by the radiation-induced solid-state postpolymerization of trioxane with 1,3-dioxolane have been carried out. Gas-chromatographic analysis of the reaction mixtures showed that most of the 1,3-dioxolane disappears rapidly from the reaction system in an early stage of polymerization, and that the fraction of ethylene oxide units in the copolymer chain [E] decreases markedly with increasing polymer yield. This finding was confirmed by NMR spectra of the copolymer. DSC thermograms of the copolymer indicated that the relationship between the melting point and the average composition of copolymers prepared in this study differed from that found for copolymers in which comonomer units are distributed statistically in the polymer chain. It was suggested that the copolymer formed by the radiation-induced solid-state postpolymerization of trioxane–1,3-dioxolane is characterized by a heterogeneous distribution of ethylene oxide units in the copolymer chain. It was also found that, in the radiation-induced solid-state postpolymerization of trioxane–1,3-dioxolane, the amount of tetraoxane formation increased linearly with increasing polymer yield. Although it is extremely small compared with that obtained in solution polymerization, it is slightly larger in the trioxane–1,3-dioxolane system than in the trioxane system.     

γ-Ray-induced copolymerization of carbon monoxide with cyclic ethers

The γ-ray copolymerization of carbon monoxide with cyclic ethers, such as ethylene oxide, phenyl glycidyl ether, 1,3-dioxolane, 2-vinyl-1,3-dioxolane, terahydrofuran, 1,4-dioxane, and acetaldehyde was studied. A yellowish or brownish powdery copolymer was obtained in most of the cases examined. The infrared spectra showed that copolymers containing the ester structural unit were produced in the copolymerization with cyclic ethers which have no vinyl groups, and that a copolymer containing a ketone structure was produced from cyclic ether having vinyl group. It was found that the copolymer with ethylene oxide also had a β-propiolactone ring structure at the chain end or the side chain. The copolymers were confirmed to be partially crystalline from the x-ray diffraction diagrams. Further, a ring-opening polymerizability of the cyclic ether by γ-radiation was discussed. And it was found that as the bond dissociation energy between the carbon–oxygen linkage of the cyclic ether is small, the polymer yield both in the homopolymerization and copolymerization with carbon monoxide is high. A mechanism for the copolymerization is proposed on the basis of the results.     

Expected and unexpected reactions in ring‐opening (co)polymerization

This review covers most of the authors' work on ring‐opening polymerization and copolymerization of heterocyclic monomers during the time of their cooperation since 1985. The mechanistic aspects of anionic ring opening polymerization of cyclic carbonates with a variety of functional groups are described first. By sequential polymerization of first styrene, methyl methacrylate or suitable heterocyclic monomers and then secondly a cyclic carbonate, the site transformation is highlighted. The influence of the chemical nature of macroinitiators with identical active sites on the course of polymerization of cyclic carbonates was studied for poly(ethylene oxide), poly(tetrahydrofuran), and poly(dimethylsiloxane) macroinitiators. For the copolymerization of cyclic carbonates with lactones and lactide the dependence of the polymer microstructure on the polymerization conditions is discussed on the basis of the copolymerization mechanism. The copolymerization of cyclic carbonates with ε‐caprolactam and with tetramethylene urea results in an alternating copolymer, i. e. a poly(ester urethane) and an [m, n]‐polyurethane, respectively, the key step being the insertion of the lactam or the cyclic urea into the carbonate chain. The cationic ring opening polymerization of cyclic six and seven membered carbamates leading to [4]‐ and [5]‐polyurethane with uniform microstructure is reported with respect to kinetic, mechanistic, and thermodynamic aspects. This new access to [n]‐polyurethanes by a chain growth reaction allows the synthesis of well defined polymer architectures with polyurethane sequences. Sequential polymerization of tetrahydrofuran and the cyclic carbamate with mono‐ and bifunctional initiators leads to the respective A–B and B–A–B block copolymers. Site transformation from the oxonium to the immonium active species is the key step in the polymerization mechanism. Finally, mechanistic aspects of the ring‐opening polymerization of cyclic ester‐amides are presented.     

Fundamental considerations on the mechanism of copolymerization of trioxane and ethylene oxide initiated with boron trifluoride dibutyl etherate

A comprehensive mechanistic scheme that accounts for the unique experimental features of the copolymerization of bulk trioxane (TOX) with 2% (wt/wt) ethylene oxide (EO) was developed. The formation of the primary initiating species is shown as the diffusion-limited reaction of trace water with boron triflouride dibutyletherate [BF₃O(Bu)₂] to form a Bronsted acid. This acid complexes principally with the more basic EO and partly with the less basic TOX. The acid-complexed TOX depolymerizes to formaldehyde which can react with acid-complexed EO in an insertion reaction to form an acid-complexed dioxolane. Further insertion of formaldehyde yields an acid-complexed trioxepane. This sequence is generalized into a propagation scheme that involves propagation by expansion and ring opening. Displacement of complexed dioxolane and trioxepane can occur in the event that the more basic EO attacks the oxonium-active site at the reactive position outside the oxonium ring. These displacement reactions account for the observation of formation of dioxolane and trioxepane. The polymerization of formaldehyde is not considered significant until all EO has been consumed. During the latter stages of polymerization, cyclic oxonium-active sites are transformed into oxocarbenium sites that are stabilized by complexation with the polymer chain. This complexation is the origin of the phenomena of transacetalization and hydride transfer.     

Preparation of fluorine-containing polyethers

Polyethers were prepared from 3,3,3-trifluoro-1,2-epoxypropane by using both cationic and anionic initiators. Aluminum chloride and boron trifluoride were the two cationic initiators investigated. The polymer obtained with the use of aluminum chloride contained no functional endgroups other than hydroxyl, while the polymer prepared with boron trifluoride contained some terminal unsaturation. Potassium hydroxide and the monosodium salt of hexafluoropentanediol were investigated as anionic initiators. The polymer obtained by using potassium hydroxide also contained terminal unsaturation, while the polymer prepared with the monosodium salt of hexafluoropentanediol was terminated with primary hydroxyl groups capable of being used in polyurethanes. All polymers had molecular weights in the range from 970 to 4300. A fluorine-containing polyformal was prepared in high yield by the reaction of hexafluoropentanediol with trioxane. The same polymer was obtained in poor yield by the reaction of hexafluoropentanediol with dibutyl formal. Ring-opening polymerizations were attempted on two fluorinated cyclic ethers, 2,2,3,3,4,4-hexafluoropentamethylene oxide and 3,3,4,4-tetrafluorotetramethylene oxide. There was no reaction with anionic initiators. With most of the cationic initiators, there was no reaction. Boron trifluoride and phosphorus pentafluoride formed complexes with the ether, but would not cause ring opening.     

Synthesis of poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyl groups and its further initiation of the grafting polymerization of styrene

A new stratagem for the synthesis of amphiphilic graft copolymers of hydrophilic poly(ethylene oxide) as the main chain and hydrophobic polystyrene as the side chains is suggested. A poly(ethylene oxide) with pending 2,2,6,6‐tetramethylpiperidine‐1‐oxyls [poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide)] was first prepared by the anionic ring‐opening copolymerization of ethylene oxide and 4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl, and then the graft copolymerization of styrene was completed with benzoyl peroxide as the initiator in the presence of poly(4‐glycidyloxy‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl‐co‐ethylene oxide). The polymerization of styrene was under control, and comblike, amphiphilic poly(ethylene oxide)‐g‐polystyrene was obtained. The copolymer and its intermediates were characterized with size exclusion chromatography, ¹H NMR, and electron spin resonance in detail. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3836–3842, 2006     

Development of an Advanced Process for Manufacturing Polyacetal Resin

Abstract

An advanced process for manufacturing polyacetal resin has been developed. First, a new technology for the production of highly concentrated aqueous formaldehyde was developed by oxidizing methylal. Whereas the oxidation of methanol yields 1 mol water per mole formaldehyde, methylal oxidation produces only 1 mol water for every 3 mol formaldehyde. Thus, the output from methylal oxidation is more than 70% formaldehyde, compared with 55% from methanol oxidation. Second, a new extraction distillation process for formaldehyde purification was developed in order to get highly purified formaldehyde directly from formalin. By using highly purified formaldehyde, an end-capped polymer was obtained in the presence of acetic anhydride as a chain transfer or end-capping agent during polymerization. Third, the relatively high formaldehyde concentration enhances the formation of trioxane. Purified trioxane is copolymerized with ethylene oxide in the presence of an end-capping agent to get an end-capped polymer with high thermal stability. Two new intermediates from the initiation reaction of the copolymerization, 1,3,5,7-tetraoxacyclononane (TOCN) and 1,3,5,7,10-pentaoxacyclododecane (POCD), were isolated, and a new initiation mechanism was proposed. Fourth, the world's first acetal block copolymer was commercialized by the polymerization of formaldehyde in the presence of a lubricant functional polymer having an active hydrogen atom. This acetal block copolymer exhibits super lubrication properties.     

Cationic ring‐opening copolymerization behavior of trioxane and seven‐membered cyclic carbonate

Cationic ring‐opening copolymerization behavior of trioxane (TOX) and a seven‐membered cyclic carbonate, 1,3‐dioxepan‐2‐one (7CC) is described. When TOX and 7CC were cationically copolymerized under various feed ratios using trifluoromethane sulfonic acid (TfOH) as an initiator in nitrobenzene at 30 °C, 7CC was consumed faster than TOX and the decarboxylation was accompanied to afford the corresponding polyacetal–polycarbonate type copolymers containing poly(oxytetramethylene) units. The copolymer composition could be controlled by the feed ratio of 7CC, whose increase resulted in the high copolymer composition of the 7CC unit. The solubility of the copolymers increased as the increase of the 7CC content. Thermogravimetric, size‐exclusion chromatographic, and X‐ray analyses of the copolymers suggest that the sequences of the copolymer chains consist of the segments containing the units originated from 7CC and those with TOX unit‐rich compositions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 733–739, 2008     

Synthesis and ring-opening copolymerization of cyclic aryl ester dimers

Two kinds of cyclic aryl ester dimers have been synthesized by reaction of phthaloyl dichloride with bisphenols via interfacial polycondensation. The cyclic dimers readily undergo anionic ring-opening polymerization or copolymerization in the melt by using sodium benzoate as the initiator, producing linear, high molecular weight polyesters. The contents of cyclic dimers in the homopolymers P1, P2, and copolymer P12 are 13.7%, 10.2%, 2.9%, respectively, which indicates that ring-opening copolymerization of cyclic dimers may impel the conversion of cyclic dimers and decrease the content of cyclic dimers in the resulting copolymer. Moreover, the isothermal chemorheology of the ring-opening copolymerization of cyclic dimers indicates that the reactivemoltenmixture has low shear viscosity and the viscosity increases slowly in the initial stage of ring-opening polymerization.     

Alternating copolymerization of ethylene oxide and sulfur dioxide

Copolymerization of ethylene oxide (EO) and sulfur dioxide (SO₂) was conducted by using a variety of amines as catalyst. Aromatic tertiary amines such as quinoline and pyridine were found to show the best catalytic property of the various amines, and copolymerization was carried out in the temperature range between 0 and 80°C with the use of quinoline. The copolymerization rate was approximately first-order in quinoline, EO, and also SO₂. The copolymer, was always composed of the two monomers: 1:1 ratio, independent of the initial concentration of the monomers. The copolymer obtained was a transparent viscous material which decomposed at 218°C to afford a considerable amount of ethylene sulfite. Spectroscopic analysis of the copolymer combined with the results of elemental analysis indicates the copolymer to have the structure The polymerizability of ethylene sulfite, which might be considered an intermediate compound in the copolymerization, was also examined at 60°C for 4 hr in the presence of quinoline, and it was found that ethylene sulfite could not be polymerized under these conditions.     

Copolymerization of trioxane with styrene catalyzed by BF3·O(C2H5)2

It was determined whether trioxane, a cyclic formal, can copolymerize with styrene, a vinyl monomer, in the presence of BF₃·O(C₂H₅)₂ catalyst at 30°C. The methanol-in-soluble fraction after extraction with benzene was found to contain the copolymer of styrene and trioxane, thus demonstrating that trioxane can copolymerize with styrene In this case the amount of the methanol-insoluble polymer was less than that of the total monomer consumed, as determined by gas chromatography. This was found to be caused partly by the formation of the cyclic oligomer, 4-phenyl-1,3-dioxane. The relative reactivity of styrene was qualitatively found to be larger than that of trioxane, not only from the rate of monomer consumption but also from the composition of the methanol-insoluble polymer obtained. In a nonpolar solvent the reactivity of trioxane increased, and the difference in reactivity between the two monomers decreased. Indeed, an apparent monomer reactivity ratio might be obtained from the relationship between the monomer composition and the monomer consumption rate or the composition of the methanol-insoluble polymer, but it did not have a quantitative meaning because of the complexity of the copolymerization reaction.     

A pH- and temperature-sensitive macrocyclic graft copolymer composed of PEO ring and multi-poly(2-(dimethylamino) ethyl methacrylate) lateral chains

A novel method for the synthesis of macrocyclic graft copolymers was developed through combination of anionic ring-opening polymerization (AROP) and atom transfer radical polymerization (ATRP). A linear α,ω-dihydroxyl poly(ethylene oxide) with pendant acetal protected hydroxyl groups (l-poly(EO-co-EEGE)) was prepared first by the anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE). Then l-poly(EO-co-EEGE) was cyclized. The crude cyclized product containing the linear byproduct was hydrolyzed and purified by being treated with α-CD. The pure cyclic copolymer [c-poly(EO-co-Gly)] was esterified by reaction with 2-bromoisobutyryl bromide, and then used as ATRP macroinitiators to initiate polymerization of 2-(dimethylamino) ethyl methacrylate (DMAEMA), and a series of pH- and temperature-sensitive macrocyclic graft copolymers composed of a hydrophilic PEO as the ring and PDMAEMA as side chains (c-PEO-g-PDMAEMA) were obtained. The behavior of pH- and temperature-sensitive macrocyclic copolymers was studied in aqueous solution by fluorescence and dynamic light scattering (DLS). The critical micellization pH values of macrocyclic graft copolymers and their corresponding linear graft copolymers (l-PEO-g-PDMAEMA) were measured. Under the same conditions, the cyclic graft copolymer with the shorter side chains gave the higher critical micellization pH value. The c-PEO-g-PDMAEMA showed the lower critical micellization pH value than the corresponding l-PEO-g-PDMAEMA. The average hydrodynamic diameters (D _h) of the micelles were measured by DLS with the variation of the aqueous solution pH value and temperature.     

环氧乙烷环氧丙烷共聚醚的研究进展

综述了环氧乙烷环氧丙烷共聚醚的聚合机理聚合工艺及其应用.环氧乙烷环氧丙烷共聚醚的聚合按其催化剂体系的机理可以分为阴离子聚合、阳离子聚合和配位聚合三类,其中阳离子聚合应用较少.在环氧乙烷和环氧丙烷开环聚合生成共聚醚的反应中,不同的反应工艺条件对生成的聚醚有着很大的影响.同样比例的环氧乙烷和环氧丙烷,因聚合反应器设计、反应器种类、起使剂种类催化剂种类与用量温度加料方式端基结构等的不同,所合成的共聚醚会产生不同的结构和性能.环氧乙烷环氧丙烷共聚形成的聚醚可以分为嵌段共聚醚和无规共聚醚两类.其中,嵌段共聚醚可以分为EPE和PEP两类.     

Preparation of the amphiphilic macro‐rings of poly(ethylene oxide) with multi‐polystyrene lateral chains and their extraction for dyes

A novel method for synthesis of amphiphilic macrocyclic graft copolymers with multi‐polystyrene lateral chains is suggested, by combination of anionic ring‐open polymerization (AROP) with atom transfer radical polymerization (ATRP). The anionic ring‐opening copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out first using triethylene glycol and diphenylmethylpotassium (DPMK) as coinitiators; the monomer reactivity ratio of them are r_1(EO) = 1.20 ± 0.01 and r_2(EEGE) = 0.76 ± 0.02 respectively. The obtained linear well‐defined α,ω‐dihydroxyl poly(ethylene oxide) with pendant protected hydroxylmethyls (l‐poly(EO‐co‐EEGE)) was cyclized by reaction with tosyl chloride (TsCl) in the presence of solid KOH. The crude cyclized product containing the extended linear chain polymer was hydrolyzed and then purified by treat with α‐CD. The pure cyclic copolymer with multipendant hydroxymethyls [c‐poly(EO‐co‐Gly)] was esterified by reaction with 2‐bromoisobutyryl bromide, and then used as macroinitiators to initiate polymerization of styrene (St), and a series of amphiphilic macrocyclic grafted copolymers composed of a hydrophilic PEO as ring and hydrophobic polystyrene as side chains (c‐PEO‐g‐PS) were obtained. The intermediates and final products were characterized by GPC, NMR and MALDI‐TOF in detail. The experimental results confirmed that c‐PEO‐g‐PS shows stronger conjugation ability with the dyes than the corresponding comb‐PEO‐g‐PS. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5824–5837, 2007     

In-situ High Resolution NMR Investigation on Polymerization Mechanism. II. Comparison between BF3·Bu2O and CI-N2PF6 as Catalysts in Homopolymerization of Trioxane and Copolymerization with Ethylene Oxide

A comparison of BF₃ ·Bu₂O and Cl-N₂PF₆ as catalysts for cationic homopolymerization and copolymerization of trioxane has been made by employing high resolution nuclear magnetic resonance techniques. While no substantial difference was detected for the homopolymerization, two important differences were observed for the copolymerization with ethylene oxide; viz., 1) with Cl-NPF₆ there is a lower build-up of formaldehyde concentration; 2) with Cl[sbnd]N₂PF₆, a lesser amount of cyclic compounds containing ethylene oxide units is formed (e.g., 1,3-dioxolane). Both observations suggest that depolymerization occurs to a lesser extent with the cl-N₂PF₆ catalyst.     

Polyglycolic acid copolymers from one‐step cationic polymerization of formaldehyde,carbon monoxide,and epoxides derived from PEG

Biodegradable polyglycolic acid (PGA) is conventionally produced via the ring‐opening polymerization of glycolide, the cyclic dimer form of glycolic acid, in the presence of mostly tin‐based catalyst initiators which are rather known to be cytotoxic materials. Our previous studies revealed an alternative method for the synthesis of PGA from the perfectly alternating copolymerization of formaldehyde (from trioxane) and carbon monoxide (CO) under BrØnsted acidic conditions. The poor physical properties of PGA (insolubility in many organic solvents, brown color, etc.) limit its use in other marketing applications in the industry. To improve on the physical properties of PGA, such as solubility and appearance, copolymerization of trioxane, CO, and a minor amount of epoxides derived from polyethylene glycol (PEG) were performed under the same reaction conditions for PGA synthesis (in DCM, at 800 psi CO pressure, with triflic acid catalyst, reaction duration of 72 hours). The results have shown that the addition of minor quantities of epoxide comonomers vastly improves the appearance of the obtained PGA copolymers and allows for the control of the polymeric properties, such as solubility and melting temperature.     

Copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2

The copolymerization of tetraoxane with styrene catalyzed by BF₃·O(C₂H₅)₂ was studied at 30°C. to determine whether a cyclic monomer can copolymerize with a vinyl monomer. The formation of the copolymer was confirmed by elementary analysis of both benzene-soluble and benzene-insoluble fractions of the polymer obtained. It was found by gas chromatography that a fairly large amount of 4-phenyl-1,3-dioxane and a small amount of trioxane were formed in the present system, in addition to polymers. Roughly a third of the total amount of the monomers reacted was consumed in the formation of methanol-insoluble polymer, a third for 4-phenyl-1,3-dioxane, and another third for trioxane and unknown products which could not be indentified. The formation of these cyclic compounds during the copolymerization may be explained in terms of a back-biting (or intramolecular transacetalization) reaction. The cationic reactivity of tetraoxane was found to be similar to that of styrene on the basis of both the consumption rate of each monomer in the copolymerizing system and the composition of the methanol-insoluble polymer obtained.     

Block copolymerization of methyl methacrylate with poly(ethylene oxide) radicals formed by high-speed stirring

A block copolymer of methyl methacrylate with poly(ethylene oxide) was synthesized by initiation with poly(ethylene oxide) radicals formed by high-speed stirring. The effects of the concentration of the monomer, the concentration of the polymer, the degree of polymerization, the rotation speed, and the solvent on the rate of copolymerization were studied. It was found that the rate of copolymerization was proportional to the concentration of the monomer and to the square root of the rate of scission of the polymer chain. The block copolymerization of methyl methacrylate monomer and styrene monomer (1 : 1 mole ratio) with poly(ethylene oxide) radicals was also carried out by the same method and it was found that the block copolymerization was a radical one.