Synthesis of Main‐Chain Liquid‐Crystalline Polyesters Containing Diphenyl Mesogens by Chemo‐Enzymatic Route †

Main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogens and flexible spacers were synthesized by chemo‐enzymatic route. The enzyme‐catalyzed polymerization showed high regio‐ and chemo‐ selectivity, and is environmentally friendly. The resulting polyesters were characterized with ¹H‐NMR, ¹³C‐NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and polarized light optical microscopy (POM).     

Synthesis of Bis(4'-hydroxyphenyl)-toluene-2, 4-diurethane for Main Chain Liquid Crystalline Poly(urethane-ester)s

Intr0ducti0nLiquidcrystallinepoIyurethaneshaveattractedconsiderableinterestsinceIimura1andhiscoworkersobtainedtheminl98l.M0stofthep0lyurethanesthathaveappearedinliteraturewerebasedonasinglemes0gen(diisocyanateordiol),whichhadbeenreactedwith0nec0unterpart(di0l0rdiisocyanate)togiveap0lyurethane.Inprevi0usinvestigations'-',compoundsusedasmesogensallhadcompletemesogeniccores,whethertheyhadliquidcrystalpropertiesornot.Thisimpliesthatthemes0geniccoresexistedbeforetheformationoftheurethanegroupsorth…     

Dynamic Rheological Characterization of A Thermotropic Liquid Crystalline Poly (aryl ether ketone)

Poly(aryl ether ketone)s (PAEKs) have been widely used as advanced materials in applications because of their excellent thermal stabilities and good chemical resistance1. The high melt viscosity is one of the major drawbacks in processing them. The synthesis of thermotropic liquid crystalline PAEKs has shed light on the solving of this problem2 because they have been proved to have melt viscosities significantly lower in nematic state than those of the isotropic PAEKs and can be melt proce…     

Synthesis and Characterization of Thermotropic Liquid Crystalline Complexes Containing Ferrocenyl Group

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Copoly(Aryl Ether)s Containing 1,10‐Phenanthroline Moieties

Abstract

Poly(aryl ether)s were synthesized by reaction of 4,7‐dichloro‐3,8‐diphenyl‐1,10‐phenanthroline and 4,7‐dichloro‐2,9‐dimethyl‐1,10‐phenanthroline with bisphenol A (BPA) in the presence of potassium carbonate in N,N‐dimethylacetamide or N‐methylpyrrolidinone. High molecular weight homopolymers could not be prepared because of the insolubility of the polymers resulting in premature precipitation from the reaction mixture. Soluble, high molecular weight copolymers were readily prepared containing up to 70 mol% of the 1,10‐phenanthroline moieties. The copolymers were all highly fluorescent with blue emission.     

Effect of Polycondensation Reaction Conditions on the Properties of Thermotropic Liquid‐Crystalline Copolyester

In this study a range of wholly aromatic copolyesters based on kink m‐acetoxybenzoic acid (m‐ABA) monomer (33 mol%) and equimolar‐linear p‐acetoxybenzoic acid (p‐ABA), hydroquinone diacetate (HQDA) and terephthalic acid (TPA) monomers (67 mol%) have been synthesized by melt polycondensation reaction process at 280°C and 260°C for different time intervals. Characterization of copolyesters were performed by solution viscosity measurement, wide–angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), hot‐stage polarized light microscopy, proton‐nuclear magnetic resonance analysis (¹H‐NMR). According to the results obtained, copolyesters showed thermotropic liquid crystalline behavior in an appropriate temperature range. The copolyesters were prepared in high yields. It was observed that the intrinsic viscosities of the copolyesters are increased regularly with increasing polymerization time and temperature. All the copolyesters were soluble in a trifluoroacetic acid/dichloromethane (30:70 v/v) except the copolyesters which were synthesized at 280°C in 5 h. According to the WAXD results; the degree of crystallinity of copolyesters were found to be between 5–15%. DSC and hot stage polarized light microscopy results showed that all the copolyesters are melt processable and a significant molecular interaction exist in a very broad temperature range (160°C and 165°C) in the nematic mesophase. The T_g values are increased with an increasing polycondensation reaction time and temperature and they were observed between 93–126°C. Fibers prepared by a hand‐spinning technique from the polymer melt exhibit well‐developed fibrillar structure parallel to the fiber axis.     

Synthesis and Properties of Poly(Aryl Ether Ketone) Copolymers with Trifluoromethyl‐Substituted Benzene in the Side Chain

The new monomer (4‐(4′‐trifluoromethyl)phenoxyphenyl)hydroquinone (TFPOPH) was synthesized in a three‐step synthesis. A series of poly(aryl ether ketone) copolymers were prepared by the reaction of (4‐(4′‐Trifluoromethyl)phenoxyphenyl)hydroquinone and hydroquinone (HQ) with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in tretramethylene sulfone (TMS). Thermal analyses of the fluorinated copolymers showed that the glass transition temperature and 5.0% weight loss temperature are similar with that of PEEK, and the crystallinity decreased with increasing of TFPOPH. For the copolymer synthesized with the molar fraction of TFPOPH in the diphenol monomers (TFPOPH, HQ) being over 0.2, no cold crystallization temperature and melting temperature were detected, indicating that these copolymers are almost amorphous. The crystal structure of the copolymers with the molar fraction of TFPOPH being not higher than 0.2 is rhombic. The solubility in polar aprotic solvents of poly(aryl ether ketone)s copolymers increases and dielectric constant decreases step by step.     

Synthesis and Characterization of H‐bonded Side‐Chain Liquid‐Crystalline Polysiloxanes

Smectic Liquid‐crystalline (LC) polysiloxanes P1～P7 were prepared using cholesteryl 6‐undec‐10‐enoyloxy‐naphthalene‐2‐carboxylate and cholesteryl 3‐sulfo‐4‐undec‐10‐enoyloxy‐benzoate in a one‐step reaction with sulfonic acid group contents ranging between 0 and wt 4.39%. With an increase of sulfonic acid groups, the glass transition temperature rose slightly; while the temperature of clear point decreased. As sulfonic groups increased, H‐bonding interaction strengthened, resulting in an increase of glass transition temperature. On the other hand, aggregates of H‐bond derived from sulfonic acids would destroy the homogeneous rigid moieties and the high‐ordered structure, resulting in a temperature of clear point decreased. In X‐ray measurement, all the polymers displayed sharp strong peaks around 2θ≈2.6° and broad peaks around 2θ ≈16.6°. The broad peaks at wide‐angle are similar, but there is great different at low angles. For the polymer without sulfonic acid, the only one strong peak at low angle indicates high‐ordered lamellar structure due to homogeneous rigid moieties. For the polymers containing more sulfonic acid, two sharp peaks appeared at low angles, and the intensities of these two peaks varied. With increase of sulfonic acid groups in the polymer systems, the hydrogen‐bonding aggregates in domains would divide the homogeneous rigid mesogens into two kinds of nanophases, that is, one containing non H‐bond mesogens and another involving H‐bonding aggregated mesogens. These two different nanophases result in different lamellar spacings.     

Synthesis and Characterization of New Unsaturated Polyesters Containing 4‐Phenylcyclohexanone Moiety in the Main Chain

Two series of new unsaturated polyesters were prepared from 2,6‐bis(p‐hydroxidebenzylidene)‐4‐phenylcyclohexanone (I) and 2,6‐divanillyidene‐4‐phenylcyclohexanone (II) with adipoyl, isophthaloyl, sebacoyl and terephthaloyl dichlorides utilizing the interfacial polycondensation technique at ambient temperature. In addition to that, the model compounds were synthesized by reacting (I) and (II) with benzoyl chloride. The model compound and polyester samples have been characterized by elemental and spectral analyses. The unsaturated polyesters have inherent viscosities of 0.96–1.63 dl/g. All the polyesters are amorphous and most of them are partially soluble in most common organic solvents, but easily soluble in concentrated sulfuric acid. Their glass transition temperatures (T_g) range from190.15 to 245.28°C, and the temperatures of 10% weight loss as high as 180 to 220°C in air, indicating that these aromatic polyesters have high T_g and excellent thermal stability.     

The Rheological and Extrusion Behaviour of Blends Based on Phenolphthalein Poly(ether-ether-sulfone) and Thermotropic Liquid Crystalline Polymer

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Synthesis and Characterization of Poly (Ether Sulfone Ketone) Containing the Phthalazinone Moiety

IntroductionHeterocyclicpolymersareaclassofpolymersthatusuallyshowexcellentthermalstabilityandhavereceivedconsiderableattentionashigh-modulusplastics.Theycanbesynthesizedbythereactionofheterocyclichandesoractivatedarylhandeswithahis(phenolate)anioninanucleophilicdisplacementreaction.Manydifferenttypesofhightemperatureheterocyclicpolymers,suchaspoly(etherimide)s,poly(aryletherbenzoxazole)s,poly(etherketone)shavebeensynthesizedbythismethodl-3.Inthispaper,anovelpoly(ethersulfoneketone)withC-Nbon…     

Synthesis and Characterization of the Side Chain Liquid Crystalline Poly(monoester｛6-[4-(p-nitrophen

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Novel Traceless Liquid‐Phase Synthesis of Coumarin Derivatives on Poly(Ethylene Glycol) Support

Coumarin derivatives were prepared by the von Pechmann reaction of PEG‐bound acetoacetate reagent with phenols in the presence of TiCl₄ in excellent yield and purity with a facile workup procedure. The polymer reagent could be recycled two to four times without diminishing the yield or purity.     

Synthesis and Characterization of Novel Poly(Arylene Ether)s from 1,3‐bis(4‐Hydroxyphenyl) Benzene

Abstract

Several poly(aryl ether)s have been prepared by the condensation of 1,3‐bis(4‐hydroxy phenyl) benzene with different trifluoromethyl activated bis‐fluoro compounds. IR, ¹H and ¹³C NMR, and elemental analyses have established the resulting polymer structures. The properties of the polymers have been evaluated by DSC, TGA, dynamic mechanical analysis (DMA) and stress–strain analysis. The polymers 1a and 1c showed semi‐crystalline behavior as evident by sharp crystalline melting peaks at 299°C and 330°C along with glass transitions at 202°C and 216°C, respectively. The polymers showed very good thermal stability in air, high modulus, and high tensile strength with low elongation at break.     

Synthesis and Characterization of Novel Poly(Arylene Ether)s from 4,4′‐Thiodiphenol

Four novel perfluoroalkylated poly(arylene ether)s have been synthesized successfully using four perfluoroalkyl‐activated bisfluoro monomers. These polymers are synthesized through nucleophilic displacement of the fluorine atoms on the benzene ring with 4,4′‐thiodiphenol and are named as 1a, 1b, 1c and 1d, respectively. The polymers obtained by displacement of the fluorine atoms exhibit weight‐average molar masses up to 3.9×10⁴ g · mol^?1 in Gel permeation chromatography. These poly(arylene ether)s showed very high thermal stability up to 548°C for 10% weight loss in TGA under nitrogen and high glass transition temperature (T_g) up to 178°C in DSC depending on the repeat unit structures. The glass transition temperatures taken as peak in tan δ in DMA measurements are in good agreement with the DSC T_g values. All the polymers synthesized are soluble in a wide range of organic solvent such as CHCl₃, CHCl₂, THF, NMP, DMF and toluene. Transparent thin films of these polymers cast from THF exhibited tensile strengths up to 72 MPa, modulus up to 1.69 GPa with low elongation at break depending on their exact repeating unit structures. Rheological properties showed ease of processability of these polymers with no change in melt viscosity with temperature.     

Synthesis of Poly(para‐phenylene) Containing Imidazolium Cation

A novel poly(para‐phenylene) containing imidazolium cation, poly[2,5‐bis[4‐(3‐methyl‐1‐imidazolium)‐butyloxy)‐1,4‐benzene dihexafluorophosphate] (PPP‐IL), has been synthesized.     

Synthesis and Properties of Aromatic Poly(Ether Sulfone)s and Poly(Etherketone)s Containing Naphthalene or Quinoline Units,and Methyl-Substituted Biphenyl-4,4′-Diols

Abstract

A series of poly(ether sulfone)s and poly(ether ketone)s were synthesized from combinations of 1,5- and 2,6-bis(4-fluorosulfonyl)naphthalene, 2,6-bis(4-fluorobenzoyl)naphthalene, and 2,6-bis(4-fluorobenzoyl)quinoline with 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol and 2,2′,3,3′,5,5′-hexamethylbiphenyl-4,4′-diol. The polycondensations proceeded quantitatively in diphenylsulfone in the presence of anhydrous potassium carbonate to afford polymers with inherent viscosities between 0.40 and 1.28 dL/g measured in N-methyl-2-pyrrolidone or concentrated sulfuric acid. The tetramethyl- and hexamethyl-substituted aromatic polyethers exhibited good thermal stability, did not decompose below 330°C in both air and nitrogen atmospheres, and had higher glass transition temperatures than the corresponding unsubstituted polymers. The methylsubstituted poly(ether sulfone)s and poly(ether ketone)s showed good solubility in such common organic solvents as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, tetrahydrofuran, chloroform, and 1,4-dioxane.     

Studies on the Phase Separation of Poly(Ether Imide)‐Modified Cyanate Ester Resin

Abstract

A high temperature thermosetting bisphenol‐A dicyanate (BADCy) was blended with a novel thermoplastic poly(ether imide) (PEI) at various composition. The phase separation behavior during isothermal curing was studied by differential scanning calorimeter (DSC), time‐resolved light scattering (TRLS), scanning electron microscopy (SEM), and rheological measurements. The results suggested that the phase structure changed from separated phase, via co‐continuous phase, to phase inversion with the increase of the PEI content. The curing conversion of BADCy was slightly affected by the composition in the blend and the curing rate was decreased with the increase of PEI content. The co‐continuous phase morphology was attributed to a spinodal decomposition. The initial concentration of PEI had an effect on the rheological behavior during phase separation. It was found by tensile test that the blend with 15 wt.% PEI had higher tensile strength and elongation at break than that without PEI.     

Synthesis and Characterization of Poly（ether amide）s Containing Bisphthalazinone and Ether Linkages

A novel aromatic diacid, 4, 4′-bis[2-(4-carboxyphenyl)phthalazin- 1-one-4-yl]-bisphenyl ether III, containing bisphthalazinone and ether linkages was prepared from nucleophilic substitution of p-chlorobenzonitrile with the bisphenol-like monomer I, followed by alkaline hydrolysis of the intermediate dinitrile II. A series of poly(ether amide)s containing bisphthalazinone and ether linkages derived from diacid III and aromatic diamines were synthesized by one-step solution condensation polymerization using triphenyl phosphite and pyridine as condensing agents. Moreover, the properties of poly(ether amide)s including thermal stability,solubility and crystallinity were also studied.     

A Novel Pentaerythritol-based Carbosilane Liquid Crystalline Dendrimer Containing 12 Nitroazobenzene Groups on the Periphery

A novel liquid crystalline dendrimer with peripheral mesogenic units was successfully prepared. Azo-reaction and Williamson synthesis were employed in the preparation of the mesogenic unit 4-[4-(6-hydroxyhexyloxy)-phenylazo]nitrobenzene (M-NO2). A terminal Si-Cl functional carbosilane dendrimer based on pentaerythritol was used as dendritic scaffold and subsequently functionalized with the aforementioned groups. Investigation of the liquid crystalline properties of the mesogen-functionalized dendrimer PCSi-IG-NO2 by polarizing optical microscopy, DSC, and X-ray diffraction showed that it exhibits smectic E (SE) phase, different from the corresponding mesogenic unit, which shows nematic phase. Furthermore, the temperatures of both the melting point and the clearing point of the mesogen-functionalized dendrimer decrease, and the temperature region of the SE phase is wider than that of the nematic phase.