Synthesis of polyacetals with various main‐chain structures by the self‐polyaddition of vinyl ethers with a hydroxyl function

To establish the optimum conditions for obtaining high molecular weight polyacetals by the self‐polyaddition of vinyl ethers with a hydroxyl group, we performed the polymerization of 4‐hydroxybutyl vinyl ether (CH₂?CH? O? CH₂CH₂CH₂CH₂? OH) with various acidic catalysts [p‐toluene sulfonic acid monohydrate, p‐toluene sulfonic anhydride (TSAA), pyridinium p‐toluene sulfonate, HCl, and BF₃OEt₂] in different solvents (tetrahydrofuran and toluene) at 0 °C. All the polymerizations proceeded exclusively via the polyaddition mechanism to give polyacetals of the structure [? CH(CH₃)? O? CH₂CH₂CH₂CH₂? O? ]_n quantitatively. The reaction with TSAA in tetrahydrofuran led to the highest molecular weight polymers (number‐average molecular weight = 110,000, weight‐average molecular weight/number‐average molecular weight = 1.59). 2‐Hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, cyclohexane dimethanol monovinyl ether, and tricyclodecane dimethanol monovinyl ether were also employed as monomers, and polyacetals with various main‐chain structures were obtained. This structural variety of the main chain changed the glass‐transition temperature of the polyacetals from approximately ?70 °C to room temperature. These polyacetals were thermally stable but exhibited smooth degradation with a treatment of aqueous acid to give the corresponding diol compounds in quantitative yields. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4053–4064, 2002     

Thermostability of polymers containing indanic units in the main chain

The acid-catalyzed stepwise polymerization of 1,1-diphenylethylene derivatives, p-di(1-phenylvinyl) benzene, bis[p-(1-phenylvinyl)phenyl]methane, 1,2-bis[p-(1-phenylvinyl)phenyl]ethane, bis[p-(1-phenylvinyl)phenyl]ether, and bis[p-(1-phenylvinyl)phenyl]sulfide produced selectively indanic-unit-containing polymers in pertinent conditions. Their molecular weights (M?_n) were in the 1600–15, 700 region after the fractionation in hot ethnol. Melting points were in the 214–281°C region. They dissolved fairly well in conventional solvents like benzene, tetrahydrofuran, and carbon tetrachloride. According to TGA they started to decompose at 397–432°C and showed 10% weight loss at 478–502°C in air at a heating rate of 5°C/min. Focusing on the thermostability, we report on their physical properties.     

Studies of solution properties of copolymers. II. Copolymer of maleic anhydride and styrene

Styrene and maleic anhydride were copolymerized in benzene. The whole polymer thus obtained was fractionated with acetone and petroleum ether as the solvent and precipitant, respectively. The viscosities and osmotic pressures of the fractions were determined in tetrahydrofuran. The relation between the intrinsic viscosity and the molecular weight, [η] = 5.07 × 10^?5 M?_n^0.81, was obtained in tetrahydrofuran. The unperturbed mean square end-to-end distance was estimated by the Stockmayer-Fixman equation. A theoretical equation for the mean square end-to-end distance for a chain of repeating units of different bond lengths a and b with a fixed valence angle θ and without restriction of internal rotation was presented and applied to this copolymer. In addition, the equation of the mean-square end-to-end distance derived by Wall for trans-polyisoprene without rotational restriction was modified for application to this copolymer. The result evaluated with our equation was about 26% smaller than that from the modified Wall equation. A steric parameter for the present copolymer is defined and discussed in comparison with those of polystyrenesulfone and polystyrene.     

Polymers derived from fluoroketones. III. Monomer synthesis,polymerization, and wetting properties of poly(allyl ether) and poly(vinyl ether)

The synthesis and polymerization of a series of perhaloalkyl allyl and vinyl ethers derived from perhaloketones is described. Data on the critical surface tension of wetting (γ_c) for high molecular weight polymers of heptafluoroisopropyl vinyl ether and low molecular weight poly(heptafluoroisopropyl allyl ether) is also presented. Preparation of the allyl ethers is a one-step, high-yield displacement reaction between the potassium fluoride–perhaloacetone adduct and an allyl halide, such as allyl bromide. The vinyl ethersare prepared by a two-step process which involves displacement of halide from a 1,2-dihaloethane with a KF–perhaloacetone adduct and dehydrohalogenation of the 1-halo-2-perhaloalkoxyethane to a vinyl ether. Low molecular weight polymers were obtained with heptafluoroisopropyl allyl ether by using a high concentration of a free-radical initiator. The low molecular weight poly(heptafluoroisopropyl allyl ether) had a γ_c of 21 dyne/cm. No polymer was obtained with tributylborane–oxygen or with VCl₃–AIR₃, with gamma radiation, or by exposure to ultraviolet light. High molecular weight polymers were obtained from heptafluoroisopropyl vinyl either by using either lauryl peroxide or ultraviolet light but not by exposure to BF₃–etherate. The γ_c for poly(heptafluoroisopropyl vinyl ether) ranged from 14.2 to 14.6 dyne/cm., and the significance of this value is discussed in relation to the γ_c for poly(heptafluoroisopropyl acrylate).     

Friedel–crafts crosslinking methods for polystyrene modification. IV. Macromolecular structure of crosslinked particles

Crosslinked polystyrene particles were prepared by Friedel–Crafts suspension crosslinking of polystyrene using 2,4-dichloromethyl-2,5-dimethyl benzene as crosslinking agent. The polymer was dissolved in nitrobenzene and reaction occurred in a 70 wt % aqueous solution of ZnCl₂ with poly(vinyl alcohol) as a suspending agent. The spherical particles produced were swollen in toluene, chloroform, and tetrahydrofuran to determine their equilbrium polystyrene volume fraction. Analysis of the crosslinked macromolecular structure gave values of number-average molecular weight between crosslinks of M?_c = 900–5900 increasing as the nominal crosslinking ratio X decreased from 0.75 to 0.0625 mol of crosslinking agent per mole of polystyrene repeating unit. Porosimetric analysis contributed to the understanding of the importance of the pore structure for swelling behavior.     

Organometallic polymers. XXV. Preparation of polyvinylferrocene

The synthetic details of solution polymerization in benzene and bulk polymerization of vinylferrocene are reported. In benzene solutions, with azobisisobutyronitrile (AIBN) as the initiator, small yields of low-polydispersity low molecular weight (M?_n ? 5000) polyvinylferrocene is obtained. However, high yields can be obtained by continuous or multiple AIBN addition. Higher molecular weight polymers and binodal polymers can be obtained as the monomer concentration is increased. In bulk polymerizations, yields of 80% can be obtained. The molecular weight increases as temperature decreases from 80 to 60°C in bulk polymerizations, and an increasing amount of insoluble polymer results. The soluble portion is often binodal, the higher molecular weight node consisting of an increasingly branched structure. Lower molecular weight polymer was readily fractionated into narrow fractions from benzene–methanol systems, but higher molecular weight polymer proved impossible to fractionate into narrow fractions due to branching.     

Use of the Pauson–Khand reaction products as monomers in the palladium(II)‐catalyzed homopolymerization and copolymerization of norbornene derivatives

New norbornene derivatives synthesized from Pauson–Khand reaction products were homopolymerized and copolymerized with norbornene with an allyl–palladium complex as a catalyst. The ketone group was tolerated by the polymerization reaction. Monomers bearing protected alcohols were easily homopolymerized. Most of the homopolymers were soluble in tetrahydrofuran, CH₂Cl₂, toluene, and cyclohexane. As the steric bulkiness of the substituent increased, the chain length of the homopolymer decreased. Copolymers with a molecular weight of up to 153,800 were formed and were soluble in tetrahydrofuran, CH₂Cl₂, toluene, and diethyl ether. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 76–83, 2003     

Kinetics of free-radical polymerization of p-vinylbenzyl methyl ether: Crosslinking by initiator free radicals

Kinetics of polymerization of p-vinylbenzyl methyl ether at low conversion either in bulk or in benzene have been found to be quite similar to those of the unsubstituted monomer styrene. Rates of polymerization initiated by peroxides or α,α′-azobisisobutyronitrile over the temperature range 50–70°C. have been found to be proportional to [Monomer][Initiator]^1/2 with an activation energy difference E_propagation – 1/2 E_termination ≈ 6 kcal./mole. Azo initiation leads to essentially unbranched poly(vinyl-benzyl methyl ether) even at very high conversions, whereas initiation of undiluted monomer by diacyl peroxides results in some crosslinking at high conversion. Use of biacetyl as a photoinitiator of polymerization over the temperature range 0–60°C. with either bulk monomer or monomer solutions in benzene has been found in each instance to yield crosslinked, insoluble polymers at low degrees of conversion. Benzene solutions of soluble polymer have been converted to high molecular weight branched polymers by free radicals generated by photolysis of biacetyl, and a substantial preference of methyl free radicals to abstract benzyl hydrogens of poly(p-vinylbenzyl methyl ether) rather than add to solvent benzene has been observed.     

Grafting by in situ coupling of epoxy groups of a living copolymer with an anionic living polymer

A tetrahydrofuran (THF) solution of the living random copolymer of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) was prepared by the living anionic copolymerization of the two monomers, using 1,1‐diphenylhexyllithium (DPHLi) as initiator, in the presence of LiCl ([LiCl]/[DPHLi]₀ = 3), at −50°C. The copolymer thus obtained has a controlled composition and molecular weight and a narrow molecular weight distribution. By introduction of an anionic living polystyrene (poly(St)) or anionic living polyisoprene (poly(Is)) solution into the above system at −30°C, a coupling reaction took place and a graft copolymer with a polar backbone and nonpolar side chains was produced. The solvent used in the preparation of the living poly(St) or poly(Is) affects the coupling reaction. When benzene was the solvent, a graft copolymer of high purity, controlled graft number and molecular weight, and narrow molecular weight distribution (M_w/M_n = 1.11–1.21) was obtained. In the coupling reaction, the living poly(St) reacted only with the epoxy groups and not with the carbonyls of the backbone polymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 105–112, 1999     

Synthesis of aromatic polyethers by Scholl reaction. V. Synthesis and polymerization of 1,3-bis[4-(1-naphthoxy) benzoyl]benzene, 1,4-bis[4-(1-naphthoxy)benzoyl]benzene,bis[4-(1-naphthoxy)phenyl]methane, 1,3-bis[4-(1-naphthoxy) phenylmethyl]benzene,and 1,4-bis-[4-(1-naphthoxy)phenylmethyl]benzene

This article describes the synthesis and the cation-radical polymerization (Scholl reaction) of 1,3-bis[4-(1-naphthoxy) benzoyl] benzene ( 6 ) and 1,4-bis[4-(1-naphthoxy) benzoyl]- benzene ( 7 ) initiated by FeCI₃. This polymerization produced poly(ether ether ketone ketone)s (PEEKK) of number average molecular weight (M?_n) up to 5400 g/mol. The synthesis of bis[4-(1-naphthoxy) phenyl] methane ( 8 ), 1,3-bis[4-(1-napthoxy) phenylmethyl] benzene ( 9 ), and 1,4-bis[4-(1-naphthoxy) phenylmethyl] benzene ( 10 ) are also described. Polyethers of M?_n up to 15400 g/mol at a FeCl₃/monomer molar ratio of 2/1 were obtained. An increased polymerizability of the monomers 9 and 10 containing two CH₂ groups versus that of the corresponding monomers containing two carbonyl groups ( 6 and 7 ) was observed. This enhanced polymerizability was explained based on the increased nucleophilicity of monomers 9 and 10 .     

Reaction rate of crosslinkings by using a metallated polymer. II. Intermolecular and intramolecular crosslinkings at the second state

Lithium-metallated styrene–p-benzylstyrene copolymer was reacted with the branched polymer with chlorine groups at the pendant chain ends (multifunctional branched polymer) in tetrahydrofuran (THF) at 25°C. The rate constant was estimated from the changes in the concentration of metallated polymer by using photometrical measurements. The various reaction conditions were chosen and it became clear that the rate constants of intermolecular (k₂₀) and intramolecular (k_3intra) crosslinkings were derived separately at the second stage. k₂₀ showed a constant value in spite of the molecular weight of crosslinker chains and was about equal to the rate constant of the grafting. The rate of intramolecular crosslinking at the second stage increased with decreasing the molecular weight of pendant chains of multifunctional branched polymer.     

Self-crosslinkable polymers. IV. Copolymerization of 1-ethenyl-4-(2,3-epoxy-1-propoxy)benzene with vinylpyridines

Soluble and self-crosslinkable linear copolymers with pendant epoxy and pyridyl groups were obtained from 1-ethenyl-4-(2,3-epoxy-1-propoxy)benzene (M₁) and vinylpyridines (M₂) by the action of α,α′-azobisisobutyronitrile. The monomer reactivity ratios were determined in tetrahydrofuran at 60°C (r₁, r₂, and vinylpyridine given): 0.467, 0.638, 4-vinylpyridine; 0.556, 1.25, 2-vinylpyridine; 0.639, 1.38, 5-ethyl-2-vinylpyridine. The Q and e values for 1-ethenyl-4-(2,3-epoxy-1-propoxy)-benzene were calculated as 1.3–1.6 and ?1.1–?1.3, respectively, with the reported Q–e values for these vinylpyridines. The intrinsic viscosities of the copolymers were found to be 0.15–0.30 in tetrahydrofuran at 30°C and to be dependent on the copolymer composition. The copolymers with these vinylpyridines were amorphous, had no clear melting points, and became insoluble crosslinked polymers under heating without further addition of any curing agents.     

Reaction rate of crosslinkings by using a metallated polymer. III. Solvent effects on rate constants of grafting and intramolecular crosslinking reactions.

Lithium-metallated (styrene-p-benzylstyrene)copolymer was reacted with chlorine-terminated polystyrene as a crosslinker polymer in a mixture of tetrahydrofuran (THF)–n-hexane at 25°C in the presence of lithium chloride(LiCl). The rate constants were estimated from the changes in the concentration of metallated polymer by photometrical measurements. As a result, the rate constant of grafting (k₁) showed a constant value in spite of a change in molecular weight of the crosslinker polymers and the addition of n-hexane. The rate constant of intramolecular crosslinkings (k_2intra) obtained in a mixed solvent (21 ～ 36 vol % of n-hexane) increased when the molecular weight of the crosslinker polymers and the extent of n-hexane were increased.     

Hyperbranched aryl polycarbonates derived from A2B monomers versus AB2 monomers

Hyperbranched aryl polycarbonates were prepared via the polymerizations of A₂B and AB₂ monomers, which involved the condensation of chloroformate (A) functionalities with tert‐butyldimethylsilyl‐protected phenols (B), facilitated by reactions with silver fluoride. The polymerization of the A₂B monomer gave hyperbranched polycarbonates bearing fluoroformate chain ends, which were hydrolyzed to phenolic chain‐end moieties and further elaborated to tert‐butyldimethylsilyl ether groups. The polymerization of the AB₂ monomer gave tert‐butyldimethylsilyl ether‐terminated hyperbranched polycarbonates. The polymerizations were conducted at 23–70 °C in 20% acetonitrile/tetrahydrofuran in the presence of a stoichiometric excess of silver fluoride for 20–40 h to afford hyperbranched polycarbonates with weight‐average molecular weights exceeding 100,000 Da and polydispersity indices of typically 2–3. The degrees of branching were determined by a reductive degradation procedure followed by high‐performance liquid chromatography. Alternatively, the degrees of branching were measurable by solution‐state ¹H NMR analyses and agreed with the statistical 50% branching expected for the polymerization of A₂B and AB₂ monomers not experiencing constructive or destructive electronic effects on the reactivity of the multiple functional groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 823–835, 2002; DOI 10.1002/pola.10167     

Synthesis and characterization of new soluble polyamides derived from 3,3′,5,5′-tetramethyl-2,2-bis[4-(4-carboxyphenoxy)phenyl]propane

A series of new soluble polyamides having isopropylidene and methyl-substituted arylene ether moieties in the polymer chain were prepared by the direct polycondensation of 3,3′,5,5′-tetramethyl-2,2-bis[4-(4-carboxyphenoxy)phenyl]propane and various diamines in N-methyl-2-pyrrolidinone (NMP) containing CaCl₂ using triphenyl phosphite and pyridine as condensing agents. Polymers were produced with moderate to high inherent viscosities of 0.85–1.47 dL g⁻¹ while the weight-average molecular weight and number-average molecular weight were in the range of 86,700–259,000 and 43,300–119,000, respectively. All the polymers were readily dissolved in polar aprotic solvents such as NMP, N,N-dimethylacetamide, and N,N-dimethylformamide, as well as less polar solvents such as m-cresol and pyridine, and even soluble in tetrahydrofuran. These polymers were solution-cast into transparent, flexible and tough films. All of the polymers were amorphous and the polyamide films had a tensile strength range of 82–122 MPa, an elongation at break range of 6–18%, and a tensile modulus range of 2.0–2.8 GPa. These polyamides had glass transition temperatures between 233–260°C and 10% weight loss temperatures in the range of 450–489 and 459–493°C in nitrogen and air atmosphere, respectively. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1997–2003, 1999     

A study of the molecular weights of tetrahydrofuran–propylene oxide copolymers by gel permeation chromatography and other methods

The cationic copolymerization of tetrahydrofuran and propylene oxide was studied in a batch system. Boron fluoride ethyl ether and 1,2-propanediol were used as catalyst—co—catalyst system. Number-average molecular weights M?_n of various copolymers were determined by vapor-pressure osmometry (VPO) and hydroxyl endgroup analysis (OH). The VPO and OH molecular weights differed considerably. To explain the differences, several copolymers were analyzed by gel permeation chromatography (GPC). The chromatograms obtained showed for each copolymer analyzed two peaks, one located in the high molecular weight region, the other in the low molecular weight region. An attempt is made to correlate the results and to show the usefulness of GPC in the characterization of THF—PO copolymers.     

Synthesis of novel asymmetric dendritic‐linear‐dendritic block copolymers via “living” anionic polymerization of ethylene oxide initiated by dendritic macroinitiators

The first synthesis of asymmetric dendritic‐linear‐dendritic ABC block copolymers, that contain a linear B block and dissimilar A and C dendritic fragments is reported. Third generation poly(benzyl ether) monodendrons having benzyl alcohol moiety at their “focal” point were activated by quantitative titration with organometallic anions and the resulting alkoxides were used as initiators in the “living” ring‐opening polymerization of ethylene oxide. The reaction proceeded in controlled fashion at 40–50 °C affording linear‐dendritic AB block copolymers with predictable molecular weights (M_w = 6000–13,000) and narrow molecular weight distributions (M_w/M_n = 1.02–1.04). The propagation process was monitored by size‐exclusion chromatography with multiple detection. The resulting “living” copolymers were terminated by reaction either with HCl/tetrahydrofuran or with a reactive monodendron that differed from the initiating dendron not only in size, but also in chemical composition. The asymmetric triblock copolymers follow a peculiar structure‐induced self‐assembly pattern in block‐selective solvents as evidenced by size‐exclusion chromatography in combination with multi‐angle light scattering. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5136–5148, 2007     

Facile one‐pot synthesis and thermal cyclopolymerization of aryl bistrifluorovinyl ether monomers bearing reactive pendant groups

A diverse pool of aryl bistrifluorovinyl ether (BTFVE) compounds with reactive pendant groups were prepared in a facile, high yielding three step “one‐pot” synthesis from commercial 4‐bromo(trifluorovinyloxy)benzene. Monomers were confirmed from ATR–FTIR, ¹H, ¹³C, and ¹⁹F NMR, and HRMS analysis. Aryl BTFVE compounds were thermally polymerized to afford perfluorocyclobutyl (PFCB) aryl ether polymers with high number–average molecular weight (M_n) for homopolymers (17,050–27,090) and copolymers with 4,4′‐bis(trifluorovinyloxy)biphenyl monomers (27,860–56,500). The PFCB aryl ether homo‐ and copolymers collectively possess high thermal stability (>299 °C in N₂) and are readily solution processable producing optically transparent films. The thermal polymerization was achieved and reactive moieties remained intact, aside from those functionalized with acrylates. In the case with acrylate functionalized polymers, orthogonal polymerization was achieved by first photopolymerizing the acrylates followed by thermal curing of the aryl trifluorovinyl ether endgroups. Preliminary results in this study produced the successful preparation of photodefinable PFCB aryl ether material. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1887–1893, 2010     

Organolithium cleavage of aliphatic polyethers,polysulfides and polyimines

Organolithium compounds and other Group IA organometallics cleave high molecular weight poly(alkylene oxides) very rapidly at room temperature in dilute benzene solution. This reaction also works on a dimeric polyepoxide such as bis(2-n-butoxyethyl)ether and much less readily on a monomeric one as 1,2-dimethoxyethane. On the other hand, a simple aliphatic monoether such as di-n-butyl ether is not cleaved under conditions several orders of magnitude more drastic than were effective on the polyethers. The mechanism for this facile polyether cleavage is proposed as a β-elimination in which the organolithium is greatly activated by chelation with the main-chain oxygen atoms of the polyether. This cleavage method has been used broadly on high molecular weight polyethers to obtain quantitative yields of hydroxyl-ended, amorphous, and crystalline polyethers (M_n = 500–10,000), many of which cannot be made by direct polymerization. Aliphatic polysulfides and an N-substituted aliphatic polyamine cleave by this same method to, respectively, mercapto-ended and secondary amine-ended polymers. The mechanism aspects of these results are discussed.     

Proposals for structure and effect of methylalumoxane based on mass balances and phase separation experiments

Methylaluminoxane prepared from trimethylaluminium on a surface of ice mainly can be described as [Al₄O₃(CH₃)₆]₄. This is shown through analysis, phase separation experiments with diethyl ether and molecular weight determinations in benzene, 1, 4-dioxane, tetrahydrofuran and trimethylaluminium. It is discussed that the reason for forming this ball-like structure is the saturation of four coordinated Al₄O₃(CH₃)₆. This molecule has a cavern which contains a solvent molecule or a molecule of trimethylaluminium. The consequences for the formation of the catalytically active structure together with metallocene are discussed.