Synthesis,characterization, and molecular modeling studies of novel polyurethanes based on 2,2′‐[ethane‐1,2‐diylbis(nitrilomethylylidene)]diphenol and 2,2′‐[hexane‐1,6‐diylbis(nitrilomethylylidene)] diphenol hard segments

Novel polyurethanes (PUs) based on 2,2′‐[ethane‐1,2‐diylbis(nitrilomethylylidene)]diphenol and 2,2′‐[hexane‐1,6‐diylbis(nitrilomethylylidene)]diphenol as hard segments containing four aromatic diisocyanates (4,4′‐diphenylmethane diisocyanate, toluene 2,4‐diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate) have been prepared. Fourier transform infrared, UV spectrophotometry, fluorescence spectroscopy, ¹H NMR and ¹³C NMR spectroscopy, thermogravimetric analysis, and differential thermal analysis have been used to determine the structural characterization and thermal properties of the segmented PUs. All the PUs contain domains of both semicrystalline and amorphous structures, as indicated by X‐ray diffraction. The acoustic properties have been calculated with the group contribution method. Molecular dynamics simulations have been performed on all the PUs to estimate the cohesive energy density and solubility parameter values, which compare well with the values calculated with the group contribution method. Furthermore, the simulation protocols have been applied to the PUs to produce X‐ray diffraction plots to determine the phase morphology of the PUs. The surface properties of the PUs have been estimated from the simulation protocols. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6032–6046, 2006     

Novel AB crosslinked polymer networks from telechelic 4‐vinylbenzyl carbamate terminated polyurethanes and different vinyl monomers

Novel AB crosslinked polymer (ABCP) networks were synthesized from telechelic 4‐vinylbenzyl carbamate terminated polyurethanes and monomers such as styrene, 4‐vinylpyridine, methyl methacrylate and butyl acrylate. Telechelic 4‐vinylbenzyl carbamate terminated polyurethanes were synthesized from polypropylene glycol‐based NCO‐terminated polyurethane and vinylbenzyl alcohol. Effect of changing the molecular weight of polypropylene glycol on the static and dynamic mechanical properties of ABCP networks from polyurethane‐polymethyl methacrylate was studied in detail. Dynamic mechanical thermal analysis results show that polymethyl methacrylate and polystyrene‐based ABCPs have good damping over a broad temperature range. ABCP networks prepared from 4‐vinylbenzyl carbamate terminated polyurethane and different monomers such as methyl methacrylate, butyl acrylate and styrene exhibit single tan δ_max value which implies excellent interlocking between the two polymers present in the ABCP networks. Static mechanical studies showed that methyl methacrylate and styrene‐based ABCP networks exhibit better tensile properties compared to other ABCP networks from butyl acrylate and 4‐vinyl pyridine monomers. Thermogravimetric analysis results revealed that the ABCP networks showed an improved thermal stability. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and properties of liquid crystalline polyurethanes

Liquid crystalline polyurethanes were prepared from 4,4′-bis(2-hydroxyethoxy)biphenyl (BHBP) and 2,4-tolylene diisocyanate (TDI). The effect of partial replacement of BHBP by 25–75 mol % poly(oxytetramethylene) diol (PTMO, M _n = 250) on the liquid crystalline properties was studied. The BHBP/TDI/PTMO polyurethanes were obtained by one- and two-step polyaddition. The polyurethanes were investigated by DSC, polarizing microscopy, x-ray, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polymers was investigated by the SALS method. Thermogravimetric investigations of the polyurethanes were also performed. All polyurethanes containing BHBP units have liquid crystalline properties. Partial replacement of BHBP by PTMO-250 considerably changes the phase transition temperatures and the range of mesophase occurrence. More homogeneous polyurethanes were obtained, if the two-step polyaddition method was applied. The polyaddition method affects the phase transition temperatures. © 1993 John Wiley & Sons, Inc.     

阻燃型聚乳酸基聚氨酯的合成与表征

以聚乳酸二醇、六次甲基二异氰酸酯和二溴新戊二醇设计合成出一系列阻燃型聚乳酸基聚氨酯。 通过核磁、凝胶色谱和红外等表征了材料的结构性能。 结果表明,二溴新戊二醇作为扩链剂可满足制备高相对分子质量聚氨酯的要求,材料的热学性能随聚乳酸二醇相对分子质量和硬段质量分数的增加而增加。 同时该类聚氨酯具有较好的力学性能,拉伸强度在50 MPa附近,接近工业级别的聚乳酸。 材料的阻燃性能随着溴质量分数的增加而增强。 当溴质量分数为8.6%,聚氨酯的极限氧指数(LOI)为28,属于难燃级别材料。     

AB CROSSLINKED POLYURETHANES THROUGH IONIC CROSSLINKING: INFLUENCE OF CROSSLINKING NETWORKS ON PHYSICO CHEMICAL PROPERTIES

Isocyanate-terminated prepolymers were synthesized using poly(tetramethylene oxide)glycol of molecular weight 1000 (PTMG₁₀₀₀) with tolylene-2,4-diisocyanate (TDI). The prepolymers were chain extended with N-methyldiethanolamine (N-MDEA) to form polyurethanes containing tertiary nitrogen. These polyurethanes were crosslinked with bromine terminated polyurethane, poly(urethane-imide), and poly(urethane-siloxane) through the formation of cationomers at tertiary nitrogen sites across the backbone polyurethanes.

The crosslinked cationomeric polyurethanes were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), mechanical analyses, (static and dynamic), and static contact angles measurements. FTIR spectral studies confirms the formation of bromine terminated poly(urethane-imide) and poly(urethane-siloxane), as well as quaternization of the tertiary nitrogen which leads to crosslinking. A comparison of thermal stabilities of crosslinked polymers with respect to the chemical nature of bromine terminated prepolymers (BTP) indicates improved thermal stability for poly(urethane-imide) based ABCP. Stress-strain analysis shows high elongation values for poly(urethane-siloxane) and poly(urethane-imide) based ABCPs. Dynamic mechanical analysis reveals better damping for poly(urethane- siloxane) based AB crosslinked polymers.     

Synthesis and properties of new polybenzimidazoles and N-phenyl polybenzimidazoles with flexibilizing spacers on the polymer backbone

Several new polybenzimidazoles (PBIs) and N-phenyl PBIs were synthesized by high temperature solution polycondensation techniques. Three different tetramine hydrochlorides and one N-phenyl tetramine hydrochloride were condensed independently with p-phenylenedioxydiacetic acid (PDDA), 2,2′-[isopropylidene bis(p-phenyleneoxy)] diacetic acid (bisacid A₂) and 2,2′-[sulfonyl bis(p-phenyleneoxy)] diacetic acid (bisacid S) in polyphosphoric acid (PPA) at high temperatures. The polymers were obtained in 55–65% yield with inherent viscosities in the range 0.58–0.96 dL/g. Four model benzimidazoles (MBI) were also synthesized to confirm the formation of polybenzimidazoles. The PBIs and MBIs were characterized by infrared spectroscopy and elemental analysis. The properties of the polymers such as solubility, density, crystallinity, and thermal, thermoxidative, and isothermal stabilities were studied.     

New thermoplastic poly(carbonate-urethane)s based on chain extenders with sulfur atoms

New thermoplastic segmented polyurethanes were obtained by a one-step melt polyaddition using 40, 50 and 60 mol% poly(hexane-1,6-diyl carbonate) diol of \(\bar{M}_{n} = 860\) g mol^?1, 1,1′-methanediylbis(4-isocyanatobenzene) and 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol, 2,2′-[oxybis(benzene-1,4-diylsulfanediyl)]diethanol or 2,2′-[sulfanediylbis(benzene-1,4-diylsulfanediyl)]diethanol as a chain extender. FTIR, atomic force microscopy, differential scanning calorimetry and thermogravimetry were used to examine the polyurethanes’ structure and thermal properties. Moreover, their Shore A/D hardness, tensile, adhesive and optical attributes were determined. They were transparent high-molar-mass materials showing good tensile strength (up to 51.9 MPa). The polyurethanes exhibited improved adhesion to copper taking into consideration that of conventional ones, and middle or high refractive index values (1.57–1.60), and both these parameters increased with an increase of the content of sulfur atoms in the polyurethane chain. The newly obtained polyurethanes can be considered as materials for numerous medical and optical appliances.     

Thermotropic Liquid Crystalline Polymers Having Five‐Membered Heterocycles as Mesogens, 7. Synthesis and Photoluminescent Properties of Semi‐Rigid Thermotropic Liquid Crystalline Polyesters Based on a Quaterphenyl Analog of 2,2′‐Bis(1,3,4‐thiadiazole)

New semi‐rigid thermotropic liquid crystalline (LC) polyesters composed of a quaterphenyl analogue of 2,2′‐bis(1,3,4‐thiadiazole) were synthesized by high‐temperature solution polycondensation of a dioxydiundecanol derivative of 5,5′‐diphenyl‐2,2′‐bis(1,3,4‐thiadiazole) with four diacyl chlorides, whose structures were characterized by FT‐IR and ¹³C NMR spectroscopy, as well as elemental analysis. Differential scanning calorimetry (DSC) measurements and texture observations using polarizing microscopy displayed that all the polyesters form stable enantiotropic smectic and/or nematic LC phases. Solution and solid state absorption and fluorescence spectra indicated that the polyesters show absorption maxima arising from the 2,2′‐bis(1,3,4‐thiadiazole) moiety and emit bluish green light, the Stokes shifts being 129 nm in solution and 60–64 nm in the solid state. Band gap energies of the polyesters calculated from the solid state absorption spectra were 2.67–2.82 eV.     

Phase Transfer Catalysis in the Polycondensation Processes. XXV. The Relationship Between Structure and Supramolecular Ordering of Some Aromatic Polyethers Containing Flexible Spacer

Abstract

The paper presents a study concerning the influence of the chemical structure on the supramolecular ordering [crystalline, liquid crystalline (LC), or amorphous] of some aromatic polyethers. The polymers were synthesized using a phase transfer catalysis technique, in a liquid/liquid system, starting from 1,4‐dichlorobutane or 1,5‐dichloropentane and various bisphenols, as follows: 4,4′‐dihydroxyazobenzene (DHAB), 4,4′‐dihydroxydiphenyl (DHD), bisphenol A (BPA), and 2,7‐dihydroxynaphtyl (DN). All polymers were characterized by using ¹H‐NMR, DSC, and optical microscopy in polarized light. Some samples containing azobenzene moieties showed LC properties, but the majority of them resulted as semi‐crystalline compounds. If a bent bisphenol was used (BPA) to obtain homopolymers or copolymers, only amorphous products were obtained. The low thermal stability of the LC products generated some difficulties regarding the characterization of the mesophase. Generally, the copolymerization reaction influenced only the crystalline melting points, the isotropization temperature of the LC polymers being situated near their thermal degradation limit.     

Liquid crystalline properties of unsegmented and segmented polyurethanes synthesised from high aspect ratio mesogenic diols

A series of novel tetrad high aspect ratio mesogenic diol monomers 4-{[4-(n-hydroxyalkoxy)-phenylimino]-methyl}-benzoic acid 4-{[4-(n-hydroxyalkoxy)-phenylimino]-methyl}-phenyl ester were prepared with varying alkoxy spacer length (n=2,4,6,8,10) by reacting 4-formylbenzoic acid 4-formylphenyl ester and 4-(n-hydroxyalkoxy) anilines. Two series of thermotropic main chain liquid crystalline unsegmented polyurethanes (PUs) were obtained by the polyaddition of the mesogenic diols with hexamethylene diisocyanate (HMDI) and methylene bis(cyclohexylisocyanate) (H₁₂MDI) in dimethylformamide respectively. The effect of the incorporation of a third component namely polyol on the liquid crystalline properties of the polyurethanes was also studied. Linear segmented PUs were synthesised by a two-step block copolymerisation method. The PUs synthesised were based on six spacer mesogenic diol chain extender, soft segments poly(tetramethylene oxide)glycol (PTMG) (M_n= 650,1000,2000) and polycaprolactone diol (PCL) (M_n=530,1250,2000) of varying molecular weights and different diisocyanates including HMDI, H₁₂MDI and methylene bis(phenylene isocyanate) (MDI). Structural elucidation was carried out by elemental analysis, fourier transform infra red (FT-IR), nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopy. Inherent viscosity of the unsegmented polymers measured in methanesulphonic acid at 26°C was in the range of 0.13 - 0.65 dL/g while the molecular weights and molecular weight distribution of the segmented polyruethanes was determined using gel permeation chromatography (GPC). Mesomorphic properties were studied by differential scanning calorimetry (DSC) and hot stage polarising optical microscopy and the thermal stability was determined by thermogravimetric(TG)analysis. The monomeric diols and the polyurethanes exhibited nematic texture and good mesophase stability. It was observed that the partial replacement of the mesogenic diol by the polyol of varying molecular weights influenced the phase transitions and the occurrence of mesophase textures. The phase transition temperatures of the investigated polyurethanes showed dependence on the chain length of the soft segment and on the content of the mesogen moiety. A higher content of mesogenic moiety was needed to obtain liquid crystalline property when the soft segment length was increased as observed in the case of PTMG. Grained and threaded textures were observed depending on the molecular weight of the soft segment, the mesogen content and the diisocyanate. The stress-strain analyses showed that the polymers bused on high molecular weight PTMG soft segment have elastomeric property while the PCL based PUs displayed no elastomeric property.     

Synthesis and characterization of certain aromatic azopolyamides

Two new aromatic diamines, 2,2′-dimethyl-4,4′-diaminoazobenzene [benzenamine-(3,3′-dimethyl-4,4′-azobis)] and 2,2′-dichloro-4,4′-diaminoazobenzene [benzenamine-(3,3′-dichloro-4,4′-azobis)] were synthesized and their structures confirmed by IR, UV-visible, ¹H-NMR, ¹³C-NMR, and mass spectra. With these diamines, 16 aromatic polyamides were synthesized by both low-temperature solution and phosphorylation polycondensation methods. The polymers were characterized by viscosity, solubility, IR, UV visible, TGA, and DTA studies.     

Synthesis and properties of segmented main‐chain liquid‐crystalline polyurethanes with a high aspect ratio mesogenic diol as a chain extender

Main‐chain liquid‐crystalline polyurethanes were synthesized based on a high aspect ratio mesogenic diol (4‐{[4‐(6‐hydroxyhexyloxy)‐phenylimino]‐methyl}‐benzoic acid 4‐{[4‐(6‐hydroxyhexyloxy)‐phenylimino]‐methyl}‐phenyl ester) as a chain extender; polycaprolactone (PCL) diol soft segments of different number‐average molecular weights (530, 1250, or 2000); and different diisocyanates, including 1,4‐hexamethylene diisocyanate (HMDI), 4,4′‐methylene bis(cyclohexyl isocyanate) (H₁₂MDI), and 4,4′‐methylene bis(phenyl isocyanate) (MDI). The structure of the polymers was confirmed with Fourier transform infrared spectroscopy, and differential scanning calorimetry and polarizing microscopy measurements were carried out to examine the liquid‐crystalline and thermal properties of the polyurethanes, respectively. The mesogenic diol was partially replaced with 20–50 mol % PCL. A 20 mol % mesogen content was sufficient to impart a liquid crystalline property to all the polymers. The partial replacement of the mesogenic diol with PCL of various molecular weights, as well as the various diisocyanates, influenced the phase transitions and the occurrence of mesophase textures. Characteristic liquid‐crystalline textures were observed when a sufficient content of the mesogenic diol was present. Depending on the flexible spacer length and the mesogenic content, grained and threadlike textures were obtained for the HMDI and H₁₂MDI series polymers, whereas the polyurethanes prepared from MDI showed only grained textures for all the compositions. The polymers formed brittle films and could not be subjected to tensile tests. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1527–1538, 2002     

Influence of the Size of Aromatic Chelate Ligands on the Structures of Cadmium(II) Tetracarboxylates Polymers: From 2D Layered Network to 3D Metal‐Organic Framework

To determine the influence of the size of the aromatic chelate ligands on the frameworks of metal tretracarboxylate polymers, two new coordination polymers [Cd(btc)_0.5 (2,2′‐bpy)] ( 1 ) and [Cd(btc)_0.5(phen)]·H₂O ( 2 ) (H₄btc = biphenyl‐3,3′,4,4′‐tetracarboxylic acid, 2,2′‐bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline) have been synthesized under similar hydrothermal conditions. In complex 1 , the dimeric Cd₂ units are linked by bridging btc^4? ligand to form a 2D layered network, whereas complex 2 possesses a 3D metal‐organic framework consisting of the dimeric Cd₂ units. The differences of two metal‐organic frameworks demonstrate that the size of the rigid aromatic chelate ligands have an important effect on the structures of their complexes. Additionally, the two complexes show strong fluorescence in the solid state at room temperature.     

STUDY ON AB-CROSSLINKED POLYMERS Ⅰ. THE SYNTHESIS AND MECHANICAL PROPERTIES OF AB-CROSSLINKED POLYMERS BASED. ON PU/PS

The AB-crosslinked polymers (i.e. ABCP) with polystyrene as chain A and vinyl group blocked prepolymers of polyurethanes (PU) as chain B were synthesized and studied. The results of dynamic mechanical spectrometry (DMS) show that the compatibility between the components A and B can be improved greatly through chemical crosslinking during the formation of ABCPs. This effect is especially pronounced when short chain prepolymers is chosen as one of the components. It is apparent that the degree of crosslinking between the two components plays a major role in determining their compatibility. Copolymerizafion of styrene with maleic anhydride in chain A can improve the compatibility and broaden the damping temperature range. Mechanical properties of the sythesized ABCPs were also studied.     

Aromatic-aliphatic copolyesters—II. Various polycondensation processes

Aromatic aliphatic copolyesters, using hydroquinone, resorcinol, 4,4′-dihydroxybiphenyl (DHBP) 2,2 bis(4-hydroxyphenyl)propane and 4,4′-dihydroxydiphenyl sulphone (DHDPS) as bisphenols and ethylene glycol as diol, have been synthesized by interfacial, low temperature and high temperature solution condensation. Relative reactivities of these bisphenols and ethylene glycol have been evaluated by various polycondensation methods at a fixed ratio of bisphenol/glycol. Decrease in the extent of polymerization and viscosity was observed by incorporation of aliphatic diol. Viscosity was also influenced by the chemical structure of the bisphenol.     

Polyesters,polyurethanes, and epoxy resin derived from 2,2′-(1,4-phenylenedivinylene)bis-5-hydroxypyridine

2,2′-(1,4-Phenylenedivinylene)bis-5-hydroxypyridine (PBHP) was used as a starting material for preparing new polyesters and polyurethanes as well as a diepoxide-bearing styrylpyridine segments. The diesters were prepared by reacting PBHP with terephthaloyl or adipoyl dichloride utilizing the interfacial polycondensation method. The diesters were prepared from the reaction of PBHP with tolylene diisocyanate or methylenebis(4-phenylisocyanate). In addition, a model diester and diurethane were synthesized by reacting PBHP with benzoyl chloride and phenyl isocyanate, respectively. Both model compounds and polymers were characterized by IR and ¹H-NMR spectroscopy, as well as by DTA and TGA. A diepoxide was also prepared from the reaction of PBHP with epichlorohydrin which was polymerized in the presence of 4,4′-diaminodiphenylsulfone. The polyester derived from PBHP and terephthaloyl dichloride was the most thermostable polymer obtained. It was stable in N₂ up to 355°C and afforded an anaerobic char yield of 59% at 800°C. The thermal stabilities of polymers were improved by curing.     

Interfacial polycondensation reactions of the new monomer 1,1′-bis(β -aminoethyl)ferrocene

Condensation polymerizations of several ferrocenecontaining monomers have been investigated, using low temperature interfacial and solution techniques. 1, 1′-bis(β-aminoethyl)ferrocene was synthesized via a 6-step process starting with ferrocene. This monomer was then copolymerized with various aromatic and aliphatic diacid chlorides as well as with diisocyanates, leading to ferrocene-containing polyamides and polyureas having moderately high to low viscosities. Using the interfacial method, film formation occurred for the polyamides. The related monomer 1,1′-bis(β-hydroxyethyl)ferrocene reacted with diacid chlorides and diisocyanates to form ferrocenecontaining polyesters and polyurethanes, respectively, using the solution method. The ferrocenecontaining condensation polymers were characterized by IR spectroscopy and examined for possible liquid crystalline behavior.     

Chiral nematic liquid crystals with helix inversion from (R)-1,1′-binaphthyl and cholesteryl ester moieties

In this study, on the concept of intramolecular chiral conflict between the (R)-1,1′-binaphthyl and cholesteryl ester moieties, we have designed and synthesised a new liquid crystal (LC) (R)-dicholesteryl 6,6′-[1,1′-binaphthyl-2,2′-diylbis(oxy)]dihexanoate [(R)-DC]. A helix inversion could be observed for the chiral nematic liquid crystal (N*-LC) comprising the commercial nematic LC (N-LC) host SLC1717 and (R)-DC on heating. As a comparison, (S)-dicholesteryl 6,6′-[1,1′-binaphthyl-2,2′-diylbis(oxy)]dihexanoate [(S)-DC] was also prepared. Due to the intramolecular chiral superposition between the (S)-1,1′-binaphthyl and cholesteryl ester moieties, the N*-LC comprising SLC1717 and (S)-DC also exhibited excellent temperature sensitivity.     

Ultrasonic Assisted Synthesis of Naphthalene Substituted Schiff Base Derivatives and Their Antioxidant Activity Studies

New Schiff base derivatives, 2,2′‐[naphthalene‐2,7‐diylbis(oxy)]bis[N′‐substituted acetohydrazide] ( 4a‐m ) were synthesized by the acid catalyzed condensation of aryl/hetero aromatic aldehydes with 2,2′‐ [naphthalene‐2,7‐diylbis(oxy)]diacetohydrazide ( 3 ) under reflux temperature and ultrasonic irradiation. These Schiff base derivatives were confirmed through spectral characterization using IR, ¹H NMR, ¹³C NMR and mass spectra. All the synthesized compounds were screened for their antioxidant activity using DPPH free radical scavenging method.     

Polyurethanes containing oxetane-derived poly(2,2-substituted-1,3-propylene oxide) soft blocks: copolymer effect on wetting behavior

Hydroxy-terminated poly(2,2-substituted-1,3-propylene oxide) telechelics and co-telechelics bearing semifluorinated (R = -CH(2)OCH(2)(CF(2))(n)CF(3), n = 0, 1) and/or bromomethyl pendant groups were synthesized from the corresponding 3,3-substituted oxetanes. The new telechelics were incorporated in polyurethanes (PUs) with isophorone diisocyanate (IPDI) and 1,4-butanediol (BD) as the hard block. Surface properties were evaluated using tapping mode atomic force microscopy (TM-AFM) and dynamic contact angle (DCA) analysis. Interestingly, polyurethanes containing P(3FOx-BrOx) have higher theta(adv) and lower theta(rec) than the homo-telechelic PUs [P(3FOx) = poly(2-methyl-2-trifluoroethoxymethyl-1,3-propylene oxide; P(BrOx) = poly(2-methyl-2-bromomethyl-1,3-propylene oxide)]. For IPDI-BD(40)/P(3FOx/BrOx-1:1), theta(adv) (116 degrees) is higher and theta(rec) (32 degrees) is lower (Deltatheta, 84 degrees ) than any other homo- or co-telechelic polyurethane. The unusual wetting behavior for P(FOx/BrOx) polyurethanes is correlated with FOx-BrOx dyad content, and a reversible H-bonding mechanism is proposed to explain the results.