Synthesis and ring‐opening polymerization of macrocyclic aromatic sulfide oligomers

A series of macrocyclic(arylene sulfide) oligomers were synthesized by reaction of 4,4′‐oxybis(benzenethiol) with a number of difluoro compounds in dimethylformamide (DMF) in the presence of anhydrous K₂CO₃ under high dilution conditions. The difluoro compound can be 4,4′‐difluorobenzophenone, bis(4‐fluorophenyl)sulfone or 1,3‐bis(4‐fluorobenzoyl)benzene. Detailed structural characterization of these oligomers by matrix‐assisted laser desorption and ionization‐time of flight‐mass spectroscopy (MALDI‐TOF‐MS) demonstrated their cyclic nature. The MALDI‐TOF‐MS technique has proved to be a powerful tool to analyze these cyclics. These cyclic oligomers are amorphous and highly soluble in DMF and N,N′‐dimethyl acetamide. Moreover, these cyclic(arylene sulfide) oligomers readily underwent ring‐opening polymerization in the melt at 285 °C in the presence of 2,2′‐dibenzothiazole disulfide, affording linear, high molecular weigh poly(aromatic sulfide)s. These polymers are insoluble in most common solvents. Copyright © 2004 Society of Chemical Industry     

One step synthesis and rapid ring‐opening polymerization of macrocyclic (arylene thioether ketone) oligomers

Well‐crystal macrocyclic (arylene thioether ketone) oligomers were synthesized under high dilution condition by the reaction of Na₂S with bis(4‐fluoro‐phenyl)‐methanone in 1‐methyl‐pyrrolidone (NMP). The oligomers were fully characterized by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra (MALDI‐TOF‐MS), high‐pressure liquid chromatography (HPLC), gel permeation chromatography (GPC), ¹H NMR, ¹³C‐NMR, and differential scanning calorimetry (DSC). According to DSC studies, uncatalyzed and rapid ring‐opening polymerization (ROP) of the oligomers took place instantly when they were heated to melting point. Extracted by dichloro‐methane, the obtained polymer neither loses any weight nor dissolves in boiling 1‐chloro‐ naphthalene. These facts indicated that there are no residual oligomers within the resultant polymer. The as‐prepared oligomers could be potentially used as high‐temperature hot‐melt adhesive at a high temperature > 350°C, and matrices for high‐performance composites and nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 161–166, 2006     

Crosslinking of poly(arylene disulfide)s and poly(arylene sulfane)s derived from cyclic(arylene disulfide) oligomers

Cyclic(arylene disulfide) and polycyclic(arylene sulfide) oligomers were synthesized by catalytic oxidation of arylenedithiols or arylenetrithiols with oxygen in the presence of a copper‐amine catalyst. These cyclic(arylene sulfide) oligomers can undergo free radical ring‐opening polymerization at an elevated temperature in the melt or solution. Polycyclic(arylene sulfide) oligomers can be used to crosslink poly(arylene disulfide)s and poly(arylene sulfane)s derived from cyclic(arylene disulfide) oligomers and elemental sulfur. The crosslinking reactions were investigated by differential scanning calorimetry and by solubility of the cured products. The minimum concentrations of polycyclic(arylene sulfide) oligomers for producing a well crosslinked poly(arylene disulfide) and poly(arylene sulfane) are 7 wt % and 10 wt %, respectively. The crosslinking reactions between poly(arylene disulfide)s, poly(arylene sulfane)s, and triallyl‐1,3,5‐triazine‐2,4,6(1H,3H,5H)‐trione (TTT) were also investigated. TTT is more efficient for crosslinking than the synthesized polycyclic(arylene disulfide) oligomers. The crosslinkable poly(arylene disulfide)s and poly(arylene sulfane)s could be potentially used as high temperature coatings, sealants, adhesives, and as matrices for high performance thermoset composites. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3069–3077, 1999     

Preparation and characterization of mono‐ and di‐d‐α‐tocopheryl polyethylene glycol 1000 succinate

Mono‐d‐α‐tocopheryl polyethylene glycol 1000 (TPGS 1000) and di‐TPGS 1000 were prepared from the synthesized TPGS 1000 mixture. The key separation step was performed by a Simulating Moving Bed chromatographic process. The chemical structures and molecular weight distrubution were characterized by ¹H‐NMR and MALDI‐TOF mass spectroscopy. NMR and MALDI‐TOF MS data confirmed the occurrence of di‐TPGS. Both NMR and MALDI‐TOF MS results showed the degree of polymerization of the two esters and the molecular mass. The melting temperatures of the two polymers were investigated by DSC and the thermal decomposition temperatures have been determined by TGA. The melting temperatures of the two esters were 33 and 15°C, separately. And the two separated TPGS esters exhibited different thermal decomposition courses. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of the biocide polyhexamethylene biguanide by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry

The biocide polyhexamethylene biguanide (PHMB) has been characterized by matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS). Previously, no method has been able to provide a detailed structural characterization of PHMB. MALDI‐TOF MS was able to detect PHMB oligomers with n ≤ 6. Six different PHMB product types were identified, which possess combinations of amine, cyanoamine, guanidine, or cyanoguanidine end‐groups. Postsource decay (PSD) fragmentation was used to confirm the correct assignment of PHMB structure for the dominant PHMB molecular ion. MALDI‐TOF MS analysis of a ¹⁵N‐labeled PHMB confirmed the correct assignment of PHMB molecular ions, and also indicated the existence of a polymerization–depolymerization equilibrium during melt polymerization of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4928–4936, 2006     

Microstructure elucidation of polyflavonoid tannins by MALDI‐TOF‐CID

High molar mass wood tannin extracts are complex mixtures that are distributed in both molar mass and chemical composition. Condensed tannins from quebracho and mimosa woods were analyzed and compared with cacao tannins using matrix‐assisted laser desorption/ionization‐time of flight (MALDI‐TOF) mass spectrometry. Although MALDI‐TOF MS reveals the oligomer structure of the tannins, this method cannot distinguish between isomers with isobaric masses, and therefore, ambiguous structural assignments were made in a number of cases. To determine the actual microstructures present, MALDI‐TOF collision‐induced dissociation (CID) experiments were conducted. MALDI‐TOF‐CID enables monomer sequence determination, and positive assignments of isobaric structures can be made. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and properties of poly(4,4′-oxybis(benzene)disulfide)/graphite nanocomposites via in situ ring-opening polymerization of macrocyclic oligomers

An effective method for the preparation of poly(4,4′-oxybis(benzene)disulfide)/graphite nanosheet composites via in situ ring-opening polymerization of macrocyclic oligomers were reported. Completely exfoliated graphite nanosheets were prepared under the microwave irradiation followed by sonication in solution. The nanocomposites were fabricated via in situ melt ring-opening polymerization of macrocyclic oligomers in the presence of graphite nanosheets. The graphite nanosheets and resulted poly(arylene disulfide)/graphite nanocomposites were characterized with field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), tensile tester and electrical conductivity measurements. Compared with pure polymer, the electrical conductivity of the poly(arylene disulfide)/graphite nanocomposites were dramatically increased and had a value of about 10⁻³ S/cm for the nanocomposite containing 5 wt% graphite. The nanocomposites exhibit as both high performance polymeric material and electrically conductive material. Therefore, they show potential applications as high temperature conducting materials.     

Detection of oxysterols in oxidatively modified low density lipoprotein by MALDI‐TOF MS

A simple method for the detection of oxysterols in oxidatively modified LDL (Ox‐LDL) has been developed using MALDI‐TOF MS. To identify the ion peaks of oxysterols, seven major oxysterols in Ox‐LDL (7α‐hydroxycholesterol, 7β‐hydroxycholesterol, 7‐ketocholesterol, 5α,6α‐epoxycholesterol, 5β,6β‐epoxycholesterol, 25‐hydroxychokesterol, (25R)‐26‐hydroxycholesterol), and cholesta‐3,5‐dien‐7‐one were analyzed by MALDI‐TOF MS. Among these oxysterols, 7‐ketocholesterol, a very abundant oxysterol in Ox‐LDL, was found to show a characteristic peak of [M + H]⁺ at m/z 401. Cholesta‐3,5‐dien‐7‐one, which is known as a degradation product of 7‐ketocholesterol upon saponification of Ox‐LDL, gave a major peak of [M + H]⁺ at m/z 383. In contrast, other oxysterols showed similar peak patterns at m/z 367 and 385. These results were applied to the analysis of Ox‐LDL by MALDI‐TOF MS after saponification and hexane‐extraction, detecting ion peaks at m/z 367, 383, 385, and 401. This MALDI‐TOF MS method has a potential as a simple tool to show the presence of oxysterols in Ox‐LDL without derivatization and chromatographic separation.     

MALDI‐TOF‐CID for the microstructure elucidation of polymeric hydrolysable tannins

High molar mass wood tannin extracts are complex mixtures that are distributed in both molar mass and chemical composition. Hydrolysable tannins from tara, Turkey gall, and chestnut woods were analyzed and compared using matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry. Although MALDI‐TOF MS reveals the oligomer structure of the tannins, this method cannot distinguish between isomers with isobaric masses and, therefore, ambiguous structural assignments were made in a number of cases. To determine the actual microstructures present, MALDI‐TOF‐CID (collision induced dissociation) experiments were conducted. MALDI‐TOF‐CID enables monomer sequence determination and positive assignments of isobaric structures can be made. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Condensation of alkoxysilanes in alcoholic media: II. Oligomerization of aminopropylmethyldiethoxysilane and co‐oligomerization with dimethyldiethoxysilane

In the context of the preservation of cultural heritage, the treatment of paper by an aminoalkylalkoxysilane, or its mixture with dimethyldiethoxysilane (DMDES), gave encouraging results. The condensation experiments presented here, carried out in alcohol medium using aminopropylmethyldiethoxysilane (AMDES) alone or with DMDES, were followed using ¹H NMR, ²⁹Si NMR and matrix‐assisted laser desorption ionization time‐of‐flight (MALDI TOF) spectroscopies. The aim was to determine whether DMDES and AMDES could copolymerize under the conditions used. An exchange reaction was observed for AMDES in ethanol in the absence of water, under conditions where no exchange took place for DMDES. In methanol, this reaction proceeded much more rapidly and the reactivity of methoxysilyl groups was higher than that of ethoxysilyl groups. In the same solvent, in the presence of water, hydrolysis, cyclization and oligomerization were observed using NMR and MALDI TOF spectroscopies. In ethanol, a kinetic study of a mixture of DMDES and AMDES showed that the condensation of the two monomers proceeded at comparables rates and MALDI‐TOF analysis gave evidence that mixed oligomers were produced, containing from one to four AMDES units. It was concluded that the co‐oligomerization did not lead to a mixture of homo‐oligomers, which would be due to different hydrolysis and condensation kinetics, but induced the formation of co‐oligomers. Copyright © 2010 Society of Chemical Industry     

Molar mass distributions of polymers from size exclusion chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: Methods for comparison

Equations are presented for calculating molar mass averages and molar mass distributions from matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF MS) data and from size exclusion chromatography (SEC) data. The utility of polydispersity is examined as an indicator of the expectation of MALDI‐TOF MS mass discrimination effects. Cumulative distributions are found to be rich in information for comparing the two techniques and are easily obtained from both SEC and MALDI‐TOF MS data. Analyses of a series of narrow molar mass distribution poly(methyl methacrylate) (PMMA) standards and one polydisperse sample have been performed with both methods. MALDI‐TOF MS did not detect dimer and trimer in the PMMA samples, and it often indicated lower amounts of high‐molar‐mass polymers than did SEC. The results showed that the distribution breadth, as evidenced by the standard deviation of the distribution (calculated from the polydispersity and number‐average molar mass), correlated well with the molar mass range observed in the MALDI‐TOF MS spectra, whereas the polydispersity alone did not. Ratioing the extremes in the molar mass concentrations measured with the SEC differential refractometer, which were necessary to adequately define molar mass distributions, showed that detector dynamic range values as high as approximately 370,000 were required for the polydisperse samples. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 627–639, 2005     

Poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane‐poly(dimethylsiloxane) block copolymers

The heterofunctional condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane with dihydroxydiphenylsilane at various ratios of initial compounds in the presence of amines was carried out, and α,ω‐dihydroxy(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane oligomers with various degrees of condensation were obtained. Corresponding block copolymers were obtained by heterofunctional polycondensation of synthesized α,ω‐dihydroxy(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane oligomers with α,ω‐dichlorodimethylsiloxanes in the presence of amines. Thermogravimetry, gel permeation chromatography, differential scanning calorimetry, and wide‐angle X‐ray analysis were carried out on the synthesized block coplymers. Differential scanning calorimetry and wide‐angle X‐ray studies of these copolymers showed that their properties were determined by the ratio of the lengths of the flexible linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)‐diphenylsiloxane fragments in the main macromolecular chain. Two‐phase systems were obtained with specific flexible and rigid fragment length values in synthesized block copolymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3462–3467, 2006     

Synthetic tannins structure by MALDI‐TOF mass spectroscopy

The structure, polymeric nature, and oligomers distribution of six types of commercial synthetic tannins (syntans) were determined by MALDI‐TOF mass spectrometry. The syntans examined were: (i) polycondensation oligomers of sulfonated phenol and 4,4′‐dioxydiphenylsulfone with formaldehyde and sodium bisulfite; (ii) sodium salts of polycondensation oligomers of phenol and sulfonated phenol with formaldehyde and urea; (iii) sodium salts of polycondensation oligomers of sulfonated phenol with formaldehyde and urea; (iv) sodium and ammonium salts of polycondensation oligomers of sulfonated naphtalene with formaldehyde; and (v) a sulfonated phenolic novolak resin. The oligomers distribution indicated that the relative abundance of oligomers from trimer to higher degrees of polymerization varied from 70% to more than 90% according to the different syntans tested. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane)– poly(dimethylsiloxane) block copolymers

The hydrolytic condensation of 1,3‐dichloro‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane under neutral conditions produced α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane (polymerization degree ≈ 4). The homofunctional condensation of α'ω‐dihydroxy‐1,3‐disila‐1,3‐diphenyl‐2‐oxaindane in a toluene solution and in the presence of activated carbon was performed, and dihydroxy‐containing oligomers with various degrees of condensation were obtained. Through the heterofunctional condensation of dihydroxy‐containing oligomers with α'ω‐dichlorodimethylsiloxanes in the presence of amines, corresponding block copolymers were obtained. Gel permeation chromatography, differential scanning calorimetry, thermomechanical analysis, thermogravimetry, and wide‐angle roentgenography investigations were carried out. Differential scanning calorimetry and roentgenography studies of the block copolymers showed that their properties were determined by the ratio of the lengths of the flexible and linear poly(dimethylsiloxane) and rigid poly(1,3‐disila‐1,3‐diphenyl‐2‐oxaindane) fragments in the macromolecular chain. At definite values of the lengths of the flexible and rigid fragments, a microheterogeneous structure was observed in the synthesized block copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1409–1417, 2002; DOI 10.1002/app.10335     

Synthesis of poly (γ‐benzyl‐L‐glutamate) with well‐defined terminal structures and its block polypeptides with alanine,leucine and phenylalanine

The ring‐opening polymerization of γ‐benzyl‐L ‐glutamate N‐carboxyanhydride (BLG‐NCA) was initiated by n‐hexylamine in N,N‐dimethyformamide under normal pressure at 0 °C. The products were characterizated by gel permeation chromatography, matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF MS), nuclear magnetic resonance etc. MALDI‐TOF MS gave direct evidence that the side reactions during the polymerization of BLG‐NCA could be greatly reduced by decreasing the reaction temperature, e.g. from room temperature to 0 °C. As a result, over 90% of the products were amino‐terminated poly(γ‐benzyl‐L ‐glutamate) (PBLG) with low polydispersity index when the polymerization was carried out at 0 °C, which could be used to re‐initiate the polymerization of other NCAs. Then several well‐defined PBLG‐containing block copolypeptides were successfully synthesized in a convenient way. Copyright © 2012 Society of Chemical Industry     

Polymer structure of commercial hydrolyzable tannins by matrix‐assisted laser desorption/ionization‐time‐of‐flight mass spectrometry

The structures of six commercial hydrolyzable tannins, chestnut, oak, tara, sumach, chinese gall, and turkey gall tannins have been examined by matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometry. Their oligomeric structures and structure distributions have been defined. Degradation products of rather different structure than what previously reported were present. Different galloyl glucose monomers were observed for chestnut and oak tannin extracts and in chinese gall gallotannin extract. Combination of positive‐ and negative‐mode MALDI‐TOF showed that most galloyl residues of the galloyl glucose chains were stripped from a skeletal glucose chain. Oligomers, in some cases up to 16 or 17 glucose units long, almost totally stripped of galloyl residues were observed. This indicated that a wide distribution up to very long gaIloylglucose chains exist in most commercial hydrolyzable tannin extracts. This indicated that these commercial tannin extracts are mainly composed of long galloyl glucose chains of mixed di‐, tri‐, and pentagalloyl glucose repeating units being present in the same chain. The presence of long glucose chains where most of the galloyl residues have been stripped indicates that their linkage may be sugar residue to sugar residue. Commercial tara and turkey gall tannins have been shown to be mainly polygallic oligomers of up to eight gallic acid residues linked to each other in a chain. Commercial sumach extract revealed itself a more complex mixture of glucose oligomers up to 13 repeating units. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of polycarbonates by melt‐phase interchange reactions with alkylene and arylene diphenyl dicarbonates

Alkylene and arylene diphenyl dicarbonates were used as monomers for the preparation of polycarbonate polymers. The diphenyl dicarbonates were first prepared from dihydroxy compounds and phenyl chloroformate. The polycarbonates were then prepared by the melt‐phase polycondensation of these diphenyl dicarbonates with dihydroxy compounds as monomers. The same polycarbonates were also synthesized by a different route involving the polycondensation of a different arylene or alkylene diphenyl dicarbonates with bisphenol A diphenyl dicarbonate to give another series of polycarbonates. The process involved precondensation under a stream of nitrogen and then melt polycondensation at a high temperature and low pressure. The prepared polycarbonates were characterized by inherent viscosity measurement, Fourier transform infrared spectroscopy, ¹H‐NMR and ¹³C‐NMR spectroscopy, and powder X‐ray diffraction. The thermal properties of the polycarbonates were studied with differential scanning calorimetry and thermogravimetric analysis. With alkylene or arylene diphenyl dicarbonates as monomers, the polycondensation reactions led to the formation of polycarbonates with inherent viscosities of up to 0.68 dL/g and with high thermal stability. The glass‐transition temperature values of the polycarbonates were in the range 24–130°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3597–3609, 2006     

Synthesis and characterization of poly(ether carbonate)s by melt‐phase interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether groups

A new method of synthesis of poly(ether carbonate)s based on interchange reactions of dihydroxy compounds with alkylene and arylene diphenyl dicarbonates containing ether group was presented. The diphenyl dicarbonate monomers were prepared from phenyl chloroformate and dihydroxy compounds containing ether group (e.g., diethylene glycol, bis(2‐hydroxyethyl ether) of bisphenol A, and 4,4′‐oxydiphenol). The process consisted of a precondensation step under a stream of dry argon followed by a melt polycondensation at 230 or at 250°C under vacuum. Four series of poly(ether carbonate)s were prepared using this approach. Using alkylene and arylene diphenyl dicarbonate‐containing ether groups as monomers, the polycondensation reaction with dihydroxy compounds led to the formation of poly(ether carbonate)s having inherent viscosity values up to 0.56 dL/g and high thermal stability. The glass transition temperature values of polycarbonates were in the range 7–122°C. The polymers were characterized by inherent viscosity and spectroscopic (Fourier transform infrared spectroscopy and ¹H‐NMR and ¹³C‐NMR) and thermal (differential scanning calorimeteric and thermogravimetric) methods. This approach may permit the use of diphenyl dicarbonates containing other organic functional groups for the synthesis of polycarbonates containing those groups. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of a novel liquid crystalline star‐shaped polymer based on α‐CD core via ATRP

Well‐defined side‐chain liquid crystalline star‐shaped polymers were synthesized with a combination of the “core‐first” method and atom transfer radical polymerization (ATRP). Firstly, the functionalized macroinitiator based on the α‐Cyclodextrins (α‐CD) bearing functional bromide groups was synthesized, confirmed by ¹H‐NMR, MALDI‐TOF, and FTIR analysis. Secondly, the side‐chain liquid crystalline arms poly[6‐(4‐methoxy‐4‐oxy‐azobenzene) hexyl methacrylate] (PMMAzo) were prepared by ATRP. The characterization of the star polymers were performed with ¹H‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and thermal polarized optical microscopy (POM). It was found that the liquid crystalline behavior of the star polymer α‐CD‐PMMAzo_n was similar to that of the linear homopolymer. The phase‐transition temperatures from the smectic to nematic phase and from the nematic to isotropic phase increased as the molecular weight increased for most of these samples. All star‐shaped polymers show photoresponsive isomerization under the irradiation with Ultraviolet light. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009