Macrocycles 27: Cyclic aliphatic polyesters of isosorbide

Numerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo‐ and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back‐biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated β‐cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3414–3424, 2003     

Syntheses of multicyclic poly(ether sulfone)s from 5,5′,6,6′‐tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐bis(4‐chlorophenyl) sulfones

5,5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐dichlorodiphenyl sulfone (DCDPS) or with 4,4′‐bis(4‐chlorophenyl sulfonyl) biphenyl (BCSBP) in DMSO. Concentration and feed ratio were optimized to avoid gelation and to obtain a maximum yield of multicyclic polyethers free of functional groups. Regardless of these reaction conditions, only low fractions of perfect multicycles were obtained from DCDPS apparently due to steric hindrance of ring closure. Under the same conditions high fractions of perfect multicycles were achieved with the longer and more flexible DCSBP. The reaction products were characterized by MALDI‐TOF mass spectrometry, ¹H‐NMR spectroscopy viscosity, and DSC measurements. Relatively low glass transition temperatures (T_gs ≈ 160–175 °C) were found. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3732–3739, 2008     

Polyimides based on new diamines having pendant imide groups

New aromatic diamines were prepared in two steps from 4,5‐dichlorophthalic anhydride and primary amines. The resulting 4,5‐dichlorophthalimide was reacted with 4‐mercaptoaniline, so that the chloroatoms were substituted by the mercapto groups (via the sulfide anions). The new diamines were polycondensed either with the diphenyl ether 3,3′,4,4′‐tetracarboxylic anhydride or with bicyclooctane tetracarboxylic anhydride. These polycondensations were conducted in boiling m‐cresol with azeotropic removal of water. The isolated polyimides were characterized by viscosity measurement, IR‐spectroscopy, elemental analyses, and MALDI‐TOF mass spectrometry. The mass spectra evidenced a high content of cyclic polyimides, indicating nearly perfect reaction conditions. The mass spectra also proved the formation of copolymers containing one diamine with a trialkylamine group in the side chain. High glass transition temperatures but a low crystallization tendency were found by DSC measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6272–6281, 2005     

Syntheses of Polyethers from Pentafluorobenzonitrile or Pentafluorobenzophenone and Flexible Diphenols

Cyanopentafluorobenzene (CPFB, pentafluorobenzonitrile) or pentafluoro‐benzophenone (PFBP) were polycondensed with long flexible diphenols at a 1∶1 feed ratio in the presence of K₂CO₃. A rather selective substitution of two C‐F groups was achieved with the formation of cyclic polyethers as the main products. Polycondensations of CPFB with flexible diphenols at 3∶2 feed ratio (a₂/b₃) yielded soluble multi‐cyclic polyethers by highly selective substitution of three C‐F groups. Yet, polycondensation at a feed ratio of 5∶2 gave a complex reaction mixture and substitution of all five C‐F groups was not observed. In all experiments, cyclization played a key role for the avoidance of gelation.     

Multicyclic polyethers by the polycondensation of 1,2‐ or 1,3‐dicyanotetrafluorobenzene with flexible diphenols

1,2‐Dicyanotetrafluorobenzene (1,2‐DCTB) was polycondensed with various flexible diphenols in a molar ratio of 1:2, and experimental parameters such as the concentration and temperature were varied. Certain diphenols allowed a complete substitution of all C? F bonds, so perfect multicyclic polyethers (B_nCN, where B stands for bridge units, C represents cycles, and N is the degree of polymerization) were the main reaction products. Despite complete conversion, gelation was avoidable under optimized reaction conditions. However, in the case of 1,3‐dicyanotetrafluorobenzene (1,3‐DCTB), complete tetrasubstitution was not feasible with a feed ratio of 1:2. Yet, because of the inductive and mesomeric electronic interactions of all substituents in 1,3‐DCTB, the three C? F groups in the ortho position with respect to the cyano groups were significantly more reactive than the fourth C? F bond. Therefore, polycondensations with diphenols in a 3:2 feed ratio showed a relatively clean course, yielding soluble multicycles of structure B_{n /2}CN. All the multicyclic polyethers were amorphous and possessed molar mass distributions with polydispersities greater than 2. Heating with Cu²⁺ salts caused crosslinking of the multicycles derived from 1,2‐DCTB because of the formation of phthalocyanine complexes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5546–5556, 2006     

Equimolar “a2 + b4” polycondensations—Cyclic polyethers derived from 1,4‐dicyanotetrafluorobenzene and various diphenols

Dicyanotetrafluorobenzene was polycondensed with bisphenol‐P, bisphenol‐M, or 1,4‐bis(4‐hydroxyphenoxy)butane in DMF. Either K₂CO₃ and ethyldiisopropylamine (EDPA) or tetramethyl piperidine (TMPD) was used as catalysts and HF acceptors. Regardless of base and concentration, all polycondensations of bisphenol‐P or 1,4‐bis(4‐hydroxyphenoxy)butane yielded more or less crosslinked polyethers. In the case of bisphenol‐M, all polycondensations conducted with K₂CO₃ and 0.4, 0.2, or 0.1 M monomer concentrations resulted again in gelation. Gels were also obtained when polycondensations of 0.4 M monomer solutions were catalyzed with EDPA or TMPD. Yet, at a concentration of 0.2 M, the amines yielded completely soluble polyethers, which were characterized by elemental analyses, inherent viscosities, MALDI‐TOF mass spectrometry, and DSC measurements. The mass spectra revealed that the soluble polyethers mainly consisted of cycles containing two C? F bonds per repeat unit. Nearly quantitative substitution of the C? F groups with 4‐chlorothiophenol, 4‐bromophenol, 4‐aminophenol, and 4‐phenyl azophenol proved successful, so that a broad variety of multifunctional polyethers was obtained, but in the case of 4‐chloro thiophenol cleavage of the polyether chain also occurred. © 2007 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 543–551, 2008     

Macrocycles. XXVIII. Cyclic poly(benzonitrile ether)s derived from bisphenol A

Bisphenol A was polycondensed with 2,6‐dichlorobenzonitrile, 2,6‐difluorobenzonitrile, 2,4‐difluorobenzonitrile, and 3,5‐difluorobenzonitrile in sulfolane. With 2,6‐and 2,4‐difluorobenzonitrile, quantitative conversions were achieved, and matrix‐assisted laser desorption/time‐of‐flight mass spectra revealed a nearly quantitative formation of cyclic oligoethers and polyethers. Furthermore, O,O′‐bistrimethylsilyl bisphenol A was polycondensed with the aforementioned dihalobenzonitriles in dry N‐methylpyrrolidone (promoted by potassium carbonate). Both the temperature and time were optimized. Only with 2,6‐difluorobenzonitrile were nearly quantitative conversions achieved, and this resulted in high molecular weights and high cycle contents. Size exclusion chromatography elution curves exhibited a tendency toward a bimodal character when larger fractions of cycles were present. Calibration with polystyrene standards indicated number‐average molecular weights of up to 10⁵ Da and weight‐average molecular weights of up to 2.3 × 10⁵ Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3838–3846, 2003     

Cyclic poly(pyridine ether)s by the polycondensation of 2,6‐difluoropyridine with various diphenols

The bistrimethylsilyl derivatives of six different diphenols were polycondensed with 2,6‐difluoropyridine in N‐methylpyrrolidone in the presence of K₂CO₃. On the basis of previous studies, the reaction conditions were optimized for almost quantitative conversions. The feed ratio was systematically varied to optimize the molecular weight. A 2 mol % excess of 2,6‐difluoropyridine was needed to obtain maximum molecular weights. In the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of the optimized polyethers, only cycles were found (detectable up to 5000 Da). Obviously, the relatively low molecular weights obtained under optimized conditions resulted from a limitation of the chain growth by cyclization, indicating a high cyclization tendency for poly(pyridine ether)s. The size exclusion chromatography measurements not only proved low molecular weights but also demonstrated the existence of bimodal mass distributions and high polydispersities. Protonation of the poly(pyridine ether)s required strong acids such as methane or trifluoromethane sulfonic acid. The solubilities of the neutral and protonated polyethers derived from bisphenol A were studied in various solvents. The MALDI‐TOF mass spectra proved that protonation at 20–25 °C did not cause cleavage of ether bonds. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4781–4789, 2005     

Preparation and Properties of Polyallenes. I. Polymerization of Allene by Ziegler-Type Catalysts

The polymerization of allene induced by organoaluminum-vanadium oxytrichloride catalysts has been investigated in aliphatic hydrocarbons and at normal pressure. For the catalysts investigated, the polymerization activity decreases at decreasing order of alkylation of the aluminum alkyl: AIR₃ > AIR₂X > AIRX₂ (R is Et or i-Bu; X is halogen). Compared with other aluminum trialkyls, trimethylaluminum shows a low activity. For the Al-i-Bu₃-VOCl₃ system, the effects of catalyst ratio, reaction time, and temperature have been studied.     

Polymers of Carbonic Acid, 31. Cyclic Polycarbonates by Hydrolytic Polycondensation of Bisphenol‐A Bischloroformate

The hydrolytic polycondensation of bisphenol‐A bischloroformate in NaOH/CH₂Cl₂ was studied using triethylamine as the catalyst. Reaction conditions were optimized towards high molar masses. The isolated polycarbonates were characterized by means of SEC and MALDI‐TOF mass spectrometry. The fraction of cyclic polycarbonates strongly increased with higher molecular weights and in the best sample only cycles were detectable (up to 50 000 Da). The largest cycles can compete with cyclic DNS of microorganisms.     

聚酰胺46的合成与结构研究：1.合成条件对产物分子量的影响

合成了高性能工程塑料聚酰胺４６并进行了基本表征，讨论了界面缩聚和溶液－固相缩聚时，有机相溶剂类型，单体浓度比，固相缩聚温度、真空度、反应时间对产物分子量的影响。     

Syntheses of cyclic polycarbonates by the direct phosgenation of bisphenol M

Bisphenol M was subjected to interfacial polycondensations in an NaOH/CH₂Cl₂ system with triethylamine as a catalyst. Regardless of the catalyst concentration, similar molecular weights were obtained, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra exclusively displayed mass peaks of cycles (detectable up to 15,000 Da). With triethyl benzyl ammonium chloride as a catalyst, linear chains became the main products, but the contents of the cycles and the molecular weights strongly increased with higher catalyst/bisphenol ratios. When the pseudo‐high‐dilution method was applied, both diphosgene and triphosgene yielded cyclic polycarbonates of low or moderate molecular weights. Size exclusion chromatography measurements, evaluated with the triple‐detection method, yielded bimodal mass distribution curves with polydispersities of 5–12. Furthermore, a Mark–Houwink equation was elaborated, and it indicated that the hydrodynamic volume of poly(bisphenol M carbonate) was quite similar to that of poly(bisphenol A carbonate)s with similar concentrations of cyclic species. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1248–1254, 2005     

Aliphatic Poly(ether amide)s by Polycondensation of Activated Sebacic Acid Derivatives

Poly(ether amide)s were prepared by polycondensation of 1,13‐diamino‐4,7,11‐trioxatridecane (DTT) with the bisimidazolide or with the bis N‐hydroxysuccinimide ester of sebacic acid. Four different solvents and three different temperatures were compared. The highest molecular weights were obtained with the bisimidazolide in dimethylsulfoxide (DMSO) at 60°C. MALDI‐TOF mass spectra revealed the existence of cyclic oligoamides and polyamides in all samples. The molar fraction of cycles considerably increased with higher molecular weights of the entire sample. The polycondensations were repeated under optimum conditions in the presence of α‐cyclodextrin to prepare polydisperse catenanes consisting of α‐cyclodextrin threaded on cyclic polyamides. Yet, despite broad variation of the reaction conditions, only cylic polyamides free of cyclodextrin were isolated. Furthermore, a pseudorotaxane was prepared from DTT and α‐cyclodetrin and polycondensed with bis‐(4‐chlorophenyl)sebacate. Again, only cyclic polyamides free of cyclodextrin were detectable.     

Syntheses of aliphatic polyesters catalyzed by lanthanide triflates

Polycondensations of 1,6‐hexane diol and sebacic acid were conducted in bulk with addition of a lanthanide triflate as acidic catalyst. With exception of promethium triflate all lanthanide triflates were studied. A particularly low molecular weight was obtained with neodym triflate and the best results with samarium triflate. With Sm(OTf)₃ weight average (M_w) values up to 65 kDa (uncorrected SEC data) were achieved after optimization of the reaction conditions. Comparison of these results with those obtained from bismuth, magnesium, and zinc triflates, on the one hand, and comparison with the acidities of all catalysts, on the other, indicates that the esterification mechanism involves complexation of monomer by metal ions. Preparation of multiblock copoly(ether ester)s failed due to insufficient incorporation of poly(tetrahydrofuran) diols. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 170–177, 2009     

Thermal polycondensation of sugar fluoride to form highly branched polysaccharide

Sugar fluorides were found to undergo powder‐to‐powder polycondensation without any catalyst at 110–160 °C under vacuum, giving highly branched polysaccharides (Conv. = 40–95%, M_w = 1400–20,000). The cross‐polarized optical microscopy at 110 °C disclosed that the crystal shape of α‐glucosyl fluoride ( FGlc ) was unchanged throughout the polymerization in spite of producing the amorphous polymer ( Poly‐FGlc ). The solid‐state post polymerization of Poly‐FGlc (M_w: 2700) at 180 °C increased the higher molecular weight (M_w: 8900). The product polysaccharide was per‐O‐methylated and subjected to structure analyses. Acid‐hydrolysis, which gave a variety of the partially O‐methylated monosaccharides, suggested that the product polysaccharides had a highly branched structure consisting of all of the possible glycosidic linkages. MALDI‐TOF mass analysis revealed that the 1,6‐anhydride terminal unit was formed and participated to the polymerization. Interestingly, α‐maltosyl fluoride hydrate ( FMal·H ₂ O ) was polymerized at the lower temperature (100 °C) than the anhydrate ( FMal ), which required 160 °C for the polymerization. They produced different structure polymers even from the same monomer. The polymer from the former consisted of the disaccharide‐repeating unit, while the repeating unit of the polymer from the latter was the monosaccharide, which was formed by the acetal exchange reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3851–3860, 2007     

非晶聚对苯二甲酸乙二酯的制备与表征

采用引入U-polymer的路线制备了非晶聚对苯二甲酸乙二酯(APET).用DSC和DMA等手段研究了APET的性能.结果表明,经改性后得到的APET无结晶,透明性得到改善,玻璃化转变温度和储能模量都较PET有一定程度提高.     

Polycondensation of H3PO4 with glycerol: From branched structures to hydrolytically reversible gels

Direct polycondensation of glycerol (GL) and phosphoric acid (PA) has been studied for the first time. Reactions were performed at 100 °C–120 °C, and in spite of the formally A₃ + B₃ process soluble poly(glycerol phosphates) could be obtained up to the high conversions. This behavior stems from the side dealkylation reaction, that is, nucleophilic attack of the hydroxyl groups on the carbon atom in the already formed macromolecules, in place of the “normal” attack on the phosphorous atom. Besides, formation of cyclic structures frustrated both high polymers formation as well as early gelation. At certain, however, ratios of reactants and at the high enough conversions highly hygroscopic gels are formed. Acidic gels were swelling in water (over 1000%) and then were converted into relatively stable, soluble products, resulting from hydrolysis of the triester knots, and containing more hydrolytically stable diesters in the chains. Thus formed highly branched macromolecules could be converted back into a gel by condensation. This process could be repeated several times. The mechanism of polycondensation is proposed: like in the previously studied polycondensation of ethylene glycol with PA, formation of pyrophosphoric acid is preceding the actual polycondensation. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3533–3542     

聚苯基膦酸二苯偶氮酯阻燃剂的合成与表征

为了解决高分子材料的耐燃性问题,阻燃剂的研究越来越受到广泛重视．聚膦酸酯类化合物是一类重要的膦系阻燃剂［１～４］,与传统的非聚合型阻燃剂相比,这种阻燃剂具有阻燃效果好、低烟低毒、与聚合物基材相容性好、耐迁移、耐挥发、阻燃效果持久等优点,成为阻燃剂研究...     

Structural variability of endotoxins from R-type isogenic mutants of Shigella sonnei

The structural variations in the rough-type endotoxins [lipopolysaccharides (LPSs)] of Shigella sonnei mutant strains (S. sonnei phase II-4303, R41, 562H and 4350) were investigated by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and tandem MS. A series of S. sonnei mutants had previously been the subject of analytical studies on the biosynthesis of heptose components in the core oligosaccharide region of LPSs. This study gives a complete overview on the structures of the full core and lipid A of S. sonnei mutant strains by MS. We found that the LPSs of the isogenic rough mutants were formed in a step-like manner containing 0:1:2:3 heptose in the deep core region of 4350, 562H, R41 and 4303, respectively, and the longest LPS from the mutant S. sonnei 4303 contained also five hexoses. The structural variations in the lipid A moiety and in the oligosaccharide part of the intact LPS were followed by MALDI-TOF-MS/MS. For the dissolution and the ionization of the samples, 2,5-dihydroxybenzoic acid in citric acid solution was applied as matrix. The detailed evaluation of the mass spectra indicates heterogeneity in the lipid part due to the differences in the phosphate and fatty acid composition.     

Unsaturated,biobased polyesters and their cross‐linking via radical copolymerization

Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2‐hydroxyethyl methacrylate, N‐vinyl‐2‐pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n‐butoxide. 2D NMR and MALDI‐Tof‐MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by‐product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their T_g values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2885–2895, 2010