Solution Polycondensation Research Articles

Synthesis of Some Polyamides from Bis(thiosemicarbazone)acenaphthenequinone

Bis(thiosemicarbazone)acenaphthenequinon (LH 6) was synthesized in one step from acenaphthoquinone and thiosemicarbazone. The diamine (LH 6) was characterized by FT-IR, 1 H NMR and melting point. diamine was used to prepare novel polyamides. The low temperature solution polycondensation of ligand with aromatic ring. Diacid chlorides and high temperature polycondensation with dicarboxylic acid afforded ligand-containing polyamides with inherent viscosities of 0.31-0.38 dL/g in N-methylpyrolidone at 25 °C. The polyamides were generally soluble in a wide range of solvents such as dimethyformamide(DMF), N-Methylpyrolidone(NMP), dimthylsulfoxide (DMSO) and H 2SO 4. Thermal analysis showed that these polyamides were practically amorphous and exhibited 10% weight loss at and above 220 °C.

Crosslinking behavior of polyarylene ether nitrile terminated with phthalonitrile (PEN‐t‐Ph)/1,3,5‐Tri‐(3,4‐dicyanophenoxy) benzene (TPh) system and its enhanced thermal stability

ABSTRACTA novel polyarylene ether nitrile terminated with phthalonitrile (PEN‐t‐Ph) was synthesized by a simple solution polycondensation of biphenyl and hydroquinone with 2,6‐dichlorobenzonitrile, followed by termination with 4‐nitrophthalonitrile. The PEN‐t‐Ph/1,3,5‐Tri‐(3,4‐dicyanophenoxy) benzene (TPh) system was prepared by cure treatment. The phthalonitrile on PEN‐t‐Ph were thermally crosslinked with TPh in the presence of diamino diphenyl sulfone through cure treatment up to 280–340°C, which led to the transformation from thermoplastic polymers to thermosetting polymers. This is because the phthalonitrile on the PEN‐t‐Ph can react with TPh by forming phthalocyanine ring. The glass transition temperatures of the PEN‐t‐Ph/TPh system increased from 152.4°C to 194.7°C, and the initial decomposition temperature (ranging from 475.3°C to 544.0°C) increased by 68°C after thermal curing. Therefore, their thermal properties can be greatly enhanced by crosslinking. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1363‐1368, 2013

Liquid crystalline polymers XI. Main chain thermotropic poly (arylidene–ether)s containing 4-methyl-cyclohexanone moiety linked with polymethylene spacers

A new homologous series of thermotropic liquid crystalline (LC) poly(arylidene−ether)s based on 4-methyl cyclohexanone moiety was synthesised by solution polycondensation of 4,4′-diformyl-α,ω-diphenoxyalkanes, Ia−f or 4,4′-diformyl−2,2′-dimethoxy-α,ω-diphenoxyalkanes IIa−f with the 4-methyl-cyclohexanone monomer. A model compound was synthesised from the monomer with benzaldehyde and characterised by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range of 0.02−0.36 dI/g. All the poly(arylidene−ether)s were insoluble in common organic solvents and partially soluble in halogenated solvents. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane spacer length. Their thermotropic LC properties were examined by differential scanning calorimetry (DSC) and optical polarising microscopy, and it was demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by thermogravimetric analysis and DSC measurements and correlated to their structural units. X-ray analysis showed that polymers have some degree of crystallinity in the region 2θ = 5−60°. In addition, the morphological properties of selected examples were tested by scanning electron microscopy.

Polybenzimidazole containing ether units as electrolyte for high temperature proton exchange membrane fuel cells

A rapid method to synthesize poly[2,2′-(p-oxydiphenylene)-5,5′-benzimidazole] (OPBI) through a solution polycondensation under microwave irradiation is explored. Synthesis parameters affecting the molecular weight (Mw) of OPBI, including the mass ratio of solvent to P2O5, the monomer concentration, and reaction time, are optimized. The main characteristics of OPBI are studied, and the corresponding membrane is prepared through a solvent casting process. A series of sulfuric acid doped OPBI (H2SO4/OPBI) hybrid membranes with different acid doping levels (ADLs) are developed. The effects of H2SO4 on microstructure, ADL and electrochemical properties of these membranes are explored. Herein, the hybrid membrane shows high proton conductivity (190 mS cm−1) at elevated temperature (160 °C) and anhydrous conditions, high ADL (18.73 mol of H2SO4 for OPBI per repeat unit, i.e., ADL = 18.73 mol PRU−1) and excellent dimensional stability (40.3%). All these properties demonstrated that H2SO4/OPBI hybrid membrane can be used as an alternative membrane for high temperature proton exchange membrane fuel cells (HT-PEMFCs).

Novel nanocomposites based on reactive organoclay of l-tyrosine and amine end-capped poly(amide–imide): Synthesis and characterization

In the present study, a series of nanocomposite materials were successfully prepared using a poly(amide–imide) (PAI) matrix and novel reactive organoclay as a reinforcing agent. The organoclay was synthesized from Cloisite Na+ and protonated form of l-tyrosine amino acid via ion-exchange reaction. It was confirmed by Fourier transform infrared spectroscopy, X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetry analysis techniques. An optically active PAI was synthesized via solution polycondensation reaction of N,N′-(pyromellitoyl)-bis-phenylalanine diacid chloride and 4,4′-diaminodiphenylether. Then it was end-capped with amine end groups near the completion of the reaction to interact chemically with organoclay. Organoclay/PAI nanocomposite films containing different amounts of organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The nanostructures and properties of the organoclay/PAI hybrids were investigated using different techniques. Thermogravimetry analysis results indicated that the addition of organoclay into the PAI matrix increased the thermal decomposition temperatures of the resulting hybrid materials. The presence of amino acids as a biodegradable segment in both novel organoclay and optically active PAI, made the resulting nanostructure materials susceptible for biodegradation.

Novel self-dyed wholly aromatic polyamide–hydrazides covalently bonded with azo groups in their main chains

Thermal characteristics of several novel self-dyed wholly aromatic polyamide–hydrazides covalently bonded with azo groups in their main chains and containing o-hydroxy group as a substituent group in the aryl ring of the aminohydrazide part of the polymers have been investigated in nitrogen and in air atmospheres using differential scanning calorimetry, thermogravimetric analyses, infrared spectroscopy, and elemental analyses. The effect of introducing different predetermined proportions of para- and meta-phenylene moieties into the backbone chain of the polymers on their thermal characteristics has been evaluated. Azopolymers having different molecular masses of all para-oriented phenylene type units were also thermally characterized. These polymers were prepared by a low temperature solution polycondensation reaction of either 4-amino-3-hydroxybenzhydrazide or 3-amino-4-hydroxybenzhydrazide with an equimolar amount of either 4,4′-azodibenzoyl chloride (4,4′ADBC), 3,3′-azodibenzoyl chloride (3,3′ADBC), or mixtures of various molar ratios of 4,4′ADBC and 3,3′ADBC in anhydrous N,N-dimethyl acetamide containing 3 % m v−1 LiCl as a solvent at −10 °C. All the polymers have the same structural formula except the mode of linking phenylene units in the polymer chain. The content of para- and meta-phenylene moieties was varied within these polymers so that the changes in the latter were 10 mol% from polymer to polymer, starting from an overall content of 0–100 mol%. The results reveal that these polymers are characterized by high thermal stability and could be cyclodehydrated into linear aromatic polymers with alternating 1,3,4-oxadiazole and benzoxazole structural units within the same polymer approximately in the region of 200–480 °C, either in nitrogen or in air atmospheres by losing water from the hydrazide and o-hydroxybenzamide groups, respectively. Along with the cyclodehydration, the polymer may lose molecular nitrogen from the azo groups. This is not a true degradation, but rather a thermo-chemical transformation reaction of the evaluated polymers into the corresponding poly(1,3,4-oxadiazolyl-benzoxazoles). The resulting poly(1,3,4-oxadiazolyl-benzoxazoles) start to decompose in the temperature range above 330–560 °C, either in nitrogen or in air atmospheres without mass loss at a lower temperature. The thermal and thermo-oxidative stabilities of the polymers are affected by the nature and amount of arylene groups incorporated into their chains, being higher for polymers with greater content of para-oriented phenylene rings, which permits more interchain hydrogen bonds as a result of greater chain symmetry, packing efficiency, and rod-like structure. Increasing the content of para-oriented phenylene rings leads to a strong improvement in both the initial decomposition temperature as well as in the residual mass at a particular temperature. The stability of the polymers was found to be independent of their molecular masses. This confirms that high thermal stability is not a polymer property which would depends upon the length of its macromolecular chains, but rather upon its chemical structure in which all and every atomic group contributes by its own thermal stability to the macroscopic properties of the whole polymer.

Synthesis of polyguanamines from 2-N,N-dibutylamino-4,6-dichloro-1,3,5-triazine with aromatic diamines

Solution polycondensation of 2-N,N-dibutylamino-4,6-dichloro-1,3,5-triazine (BDCT) with various aromatic diamines, including 4,4′-oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), o-tolidine (oTD), 4,4′-(9-fluorenylidene)dianiline (BAFL), and 2,4-diamino-6-(N,N-dibutylamino)-1,3,5-triazine (DABT), was investigated. High molecular weight (>10,000) polyguanamines (PGs) were obtained via the polymerization of BDCT with ODA, pPDA, oTD, and BAFL at 150–180°C in N-methylpyrrolidone (NMP) for 6h. The polymerizability with BDCT was determined on the basis of the molecular weights of the polymers and the chemical shifts of the NMR data as follows: ODA>oTD>BAFL>pPDA>mPDA≫DABT. PGs were obtained from the reaction of BDCT with ODA and mPDA in only 55–77% yield, which may be attributed to the formation of cyclic oligomers. All of the polymers showed high thermostability (5% weight-loss temperature in N2 greater than 444°C), and the polymers generated from reaction of BDCT with ODA, mPDA, and BAFL exhibited good solubility in tetrahydrofuran and polar aprotic solvents such as NMP.

Nanostructured amino acid containing poly(amide-imide)s from different diisocyanates: synthesis and morphology properties in molten TBAB as a green media

In this investigation, a series of nanostructured optically active poly(amide-imide)s (PAI)s were prepared via solution polycondensation of N-trimellitylimido-l-isoleucine as a chiral diacid monomer containing naturally occurring α-amino acids with different aliphatic and aromatic diisocyanates in the presence of molten tetrabutylammonium bromide (TBAB) as an environmental friendly medium and a volatile organic solvent and the results of them were comparable. In these step-growth polycondensations amino acid was used as a chiral inducing agent. The obtained polymers were characterized with respect to chemical structure and purity using specific rotation experiments, FT-IR techniques and elemental analysis. The surface morphology of these polymers was investigated by field emission scanning electron microscopy. The results indicated that the aforementioned polymers have nanostructured morphology. The obtained polymers have inherent viscosities in a range of 0.12–0.45 dL/g. Thermal stability of the resulting PAIs was studied by thermogravimetric analysis. A comparison with conventional solvents was exhibited smoothly higher inherent viscosities and better yields and thermal stability. The results showed that the molten TBAB was superior polymerization media. This process was safe and green, since toxic and volatile organic solvent such as N-methyl-2-pyrrolidone was eliminated. The observation of optical rotation confirms the optical activity of these polymers.

Synthesis and characterization of segmented copolymers of polystyrene and thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate)

A series of segmented copolymers containing a thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate) and an amorphous polystyrene were created and analyzed. The segmented copolymers were prepared by solution polycondensation of α,ω-dicarboxylic acid-terminated polystyrene with 4-hydroxybenzoic acid and 2-hydroxy-6-naphtholic acid in a mixture of triphenylphosphine, hexachloroethane, and pyridine. The obtained polymers were fractionated to isolate the pure segmented copolymers. The segmented copolymers were characterized by FT-IR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, optical polarizing microscopy (OPM), and X-ray diffraction measurement. OPM and X-ray diffraction measurements verified the presence of a nematic liquid crystalline phase for the segmented copolymers. The experimental results indicate that the segmented copolymers have a microphase-separated morphology, that is both amorphous and liquid crystalline properties were shown by the polystyrene and liquid crystalline polyester segments respectively.

The effects of reactive organoclay on the thermal, mechanical, and microstructural properties of polymer/layered silicate nanocomposites based on chiral poly(amide-imide)s

Considering the importance of the nanocomposites, the present work focuses on some new hybrid materials prepared by introducing reactive organoclay (OC) into the chiral poly(amide-imide) (PAI) matrix. At first, Cloisite Na+ was modified with protonated l-isoleucine amino acid. Then, PAI containing phenylalanine was synthesized via solution polycondensation of chiral diacid chloride with 4,4′-diaminodiphenylsulfone and was characterized with Fourier transform infrared (FTIR) and 1H NMR techniques. At last, PAI/OC nanocomposite films containing 2, 5, 10, and 15 % of OC were prepared via solution intercalation method. The effect of OC dispersion and the interaction between OC and polymer chains on the properties of nanocomposites were investigated using FTIR, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, tensile testing of thin films, and thermogravimetry analysis techniques. The thermal stability of hybrids such as the decomposition temperature and mass residue at 800 °C was improved. Mechanical data indicated improvement in the tensile strength of the nanocomposites with OC loading up to 10 wt%. The transparency of the hybrid films was investigated by means of UV–Vis spectra.

Amino Acid Based Epoxy-Poly(Ester Amide)s—A New Class of Functional Biodegradable Polymers: Synthesis and Chemical Transformations

A new class of biodegradable functional polymers – epoxy-poly(ester amide)s (EPEAs), was synthesized for the first time on the basis of naturally occurring α-amino acids, fatty diols and cis- and trans-epoxysuccinic acids. The syntheses were conducted via both solution Active Polycondensation and Interfacial Polycondensation using, accordingly, either activated di-p-nitrophenyl esters or dichlorides of cis- and trans-epoxysuccinic acids as bis-electrophilic monomers. Di-p-toluenesulfonic acid salts of bis-(L-phenylalanine)-1,6-hexylene and bis-(L-leucine)-1,6-hexylene diesters were used in both cases as bis-nucleophilic counter-partners. High-molecular-weight polymers (Mw up to 67.000) with desirable material properties were obtained via solution polycondensation using di-p-nitrophenyl-trans-epoxy succinate. The EPEAs were chemically modified further under mild conditions: oxirane groups along the backbone were reacted with both nucleophilic and electrophilic reagents, and also subjected to thermal and chemical curing. The macromolecular transformations of EPEAs substantially broaden material properties and, hence, the potential to apply amino acid-based biodegradable poly(ester amide)s as absorbable drug carriers and surgical devices.

Water insoluble cationic poly(ester amide)s: synthesis, characterization and applications.

We reported a new family of water insoluble, biocompatible and biodegradable cationic arginine and phenylalanine based poly(ester amide)s (Arg-Phe-PEAs) for potential biomedical applications. The Arg-Phe-PEA consists of 3 building blocks: amino acids, diols, and dicarboxylic acids and was prepared from both l-arginine and l-phenylalanine amino acids by solution polycondensation. The structure and properties of Arg-Phe-PEAs were characterized by standard physicochemical methods. In vitro biological tests of the Arg-Phe-PEAs included enzymatic biodegradation, cell attachment and proliferation, and macrophage inflammation tests. The enzymatic biodegradation tests showed that the biodegradation rate of Arg-Phe-PEAs can be controlled by regulating the polymer composition (the ratio of Arg to Phe). The cellular tests indicated that the bovine aortic endothelial cells (BAECs) have very good cell attachment and proliferation on the Arg-Phe-PEA surface. The in vitro inflammation data showed that the Arg-Phe-PEAs induced far lower inflammatory response than FDA approved biomaterials. By a nano-precipitation method, Arg-Phe-PEAs were formulated into nanoparticles (NPs) with particle sizes below 200 nm. The protein release profiles from Arg-Phe-PEA NPs showed that the introduction of arginine significantly enhanced the protein encapsulation efficacy and changed the protein release rate compared with pure phenylalanine based poly(ester amide)s (Phe-PEAs).

Synthesis and Application of a Novel Polyamide Charring Agent for Halogen-Free Flame Retardant Polypropylene

A novel charring agent, poly(p-ethylene terephthalamide) (PETA), for halogen-free flame retardant polypropylene was synthesized by using p-phthaloyl chloride (TPC) and ethylenediamine through solution polycondensation at low temperature, and the effects of PETA on flame retardance of polypropylene (PP)/IFR systems were studied. The experimental results showed that PETA could considerably enhance the fire retardant performance as proved by evidence of the increase of limiting oxygen index (LOI) values, the results of UL-94 tests, and cone calorimeter tests (CCT). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) demonstrated that an appropriate amount of PETA could react with PP/IFR system to form cross-link network; a more compact char layer could be formed which was responsible for the improved thermal and flame retardant properties of PP/IFR systems. However, the superfluous amount of PETA would play the negative role.

Liquid Crystalline Polymers XIII Main Chain Thermotropic Copoly (Arylidene-Ether)s Containing 4-Teriary Butyl-Cyclohexanone Moiety Linked with Polymethylene Spacers

A new homologous series of thermotropic liquid crystalline copoly(arylidene-ether)s based on 4-teriary butyl cyclohexanone moiety were synthesized by solution polycondensation of 4,4’-diformyl-α,ω-diphenoxyalkanes, Ia-d or 4,4’- diformyl-2,2’-dimethoxy-α,ω-diphenoxyalkanes IIa-d with the 4-teriary butyl-cyclohexanone III and cyclopentanone. A model compound IV was synthesized from the monomer III with benzaldehyde and characterized by elemental and spectral analyses. The inherent viscosities of the resulting polymers were in the range 0.22 - 0.92 dI/g. All the copoly(arylidene-ether)s were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and formic acid. The mesomorphic properties of these polymers were studied as a function of the diphenoxyalkane space length. Their thermotropic liquid crystalline properties were examined by DSC and optical polarizing microscopy and demonstrated that the resulting polymers form nematic mesophases over wide temperature ranges. The thermogravimetric analyses of those polymers were evaluated by TGA and DSC measurements and correlated to their structural units. X-Ray analysis showed that copolymers having some degree of crystallinity in the region 2q = 5° -60°. In addition, the morphological properties of selected examples were tested by Scanning electron microscopy.

Photocrosslinkable liquid crystalline polymers based on cyclohexanone and fluorescent heterocyclic ring system

New liquid crystalline polymers containing both fluorescent and photocrosslinking properties with various alkyl chain lengths (m = 2,4,6,8,10) were prepared by solution polycondensation reaction of 2,6-bis[4-(m-alkoxy)benzylidene]cyclohexanone and (4-phenyl)-2,6-bis (4-chlorocarbonyl phenyl)pyridine in THF using triethylamine as an acid acceptor. The polymers were characterized using various spectral techniques. These polymers were found to be thermally stable up to 377 °C confirmed by thermogravimetric analysis (TGA). Differential scanning Calorimetry (DSC) and polarized optical microscopy (POM) were carried out to study the phase structures and phase behaviors of this series of polymer. Some of the polymers with longer methylene chains demonstrated grainy type nematic LC phases. On irradiation with UV light at various time intervals, the prepared polymers showed different rate of crosslinking depending upon the alkyl chain lengths present in the polymer backbone. In addition, these polymers also show enhanced fluorescent property by the presence of heterocyclic unit in the polymer.

Thermal Degradation of Carboxymethyl Starch–g-Poly(lactic acid) Copolymer by TG–FTIR–MS Analysis

In this study, carboxymethyl starch (CMS) was grafted with l(+)-lactic acid (LA) in a CMS/LA molar ratio of 1/36, resulting in the CMS–g-PLA copolymer. The grafting reaction was carried out via a solution polycondensation procedure, in the presence of stannous 2-ethyl hexanoate [Sn(Oct)2] as a catalyst. Poly(lactic acid) (PLA) was synthesized under the same conditions with the copolymer, for comparative analyses of the thermal properties. The CMS–g-PLA copolymer, CMS, and PLA were structurally characterized by Fourier transform infrared (FTIR) spectroscopy, while thermal degradation products were characterized by thermogravimetry analysis coupled with Fourier transform infrared spectroscopy and mass spectrometry (TG–FTIR–MS). The thermal degradation was achieved in a nitrogen atmosphere, in a temperature interval of 30–600 °C. The thermal degradation of CMS and PLA was studied under the same conditions to highlight the products resulted by the thermal decomposition of CMS–g-PLA copolymer. By processing the achieved data via thermal degradation at three different heating speeds (5, 7.5, and 10 °C min–1) and using the multivariate nonlinear regression method (MNLR), the kinetic parameters were determined. The dependence of the activation energy of the degradation process versus the extent of conversion was evaluated using the Friedman and Ozawa–Flynn–Wall model-free analyses. This variation suggests that the degradation process is a complex one and can be divided in one or two steps, depending on the chemical structure of the compounds. The kinetic parameters and the most probable thermal degradation mechanisms were given.

Novel Self-Dyed Wholly Aromatic Polyamide-Hydrazides Covalently Bonded with Azo Groups in Their Main Chains: 1. Structure-Property Relationships

Twelve novel intrinsically colored wholly aromatic azopolyamide-hydrazides containing various proportions of para- and meta-phenylene units were successfully synthesized by a low temperature (−10 °C) solution polycondensation reaction of either 4-amino-3-hydroxybenzhydrazide (4A3HBH) or 3-amino-4-hydroxybenzhydrazide (3A4HBH) with an equimolar amount of either 4,4′-azodibenzoyl chloride (4,4′ADBC), 3,3′-azodibenzoyl chloride (3,3′ADBC), or mixtures of various molar ratios of 4,4′ADBC and 3,3′ADBC in anhydrous N,N-dimethyl acetamide (DMAc) containing 3% (wt/v) LiCl as a solvent. The structures of the polymers were proven by elemental analysis, FTIR, 1H- and 13C-NMR spectroscopy. The polymers’ properties were strongly affected by their various structures. The intrinsic viscosities of the polymers were ranged from 0.7 to 4.75 dL g−1 and increased with the para-phenylene units content. The polymers are partially soluble in DMAc, dimethyl formamide (DMF) and N-methyl-2-pyrrolidone (NMP). Their solubility increases with the introduction of meta-phenylene moieties into the polymer chains. The polymers exhibit a great affinity for water sorption. Their hydrophilicity increases as a function of the content of meta-phenylene rings incorporated into the polymer. Mechanical properties of the polymer films are improved markedly by substitution of para-phenylene units for meta-phenylene units. The completely para-oriented type polymer has the best thermal and thermo-oxidative stability relative to those of the other polymers.

Polymers containing phosphorus groups and polyethers: from synthesis to application

BackgroundPhosphorus-containing high performance polymers have aroused wide interest, mainly due to good mechanical properties and their excellent fire resistance. The flexibility of synthetic polyphosphoesters allows the development of polymers in order to obtain solid polymer electrolytes for rechargeable lithium batteries based on solid films with superior fire resistance.ResultsNovel linear Phosphonate-PEG polymers were synthesized by solution polycondensation of 4-chlorophenyldichlorophosphonate as a linking agent and poly(ethylene glycol)s with different molecular weights in the presence of triethylamine or 1-methylimidazole as acid scavenger. The yields were between 54% and 88% and inherent viscosity between 0.18-0.48 dl/g. Molar masses, Mn were about 26300 g/mol for polyphosphonates with PEG 2000 and 4600 g/mol for polyphosphonates with PEG 200. The LOI values for these polymers and membranes are in the range of 26–29. The membranes based on polyphosphonate with PEG 200 and 2000 showed conductivity between 6 × 10-8 S.cm-1 and 6 × 10-7 S.cm-1 at room temperature and total ionic transference number between 0.87- 0.96. The evolution of conductivity vs. temperature is linear.Conclusions1-methylimidazole was found to be better HCl scavenger than triethylamine, and allowed higher yields and more eco-friendly synthesis of the Phosphonate-PEG polymers for SPE. These polymers and membranes based on these polymers showed good LOI values and indicate an improvement of the safety of lithium batteries. The membranes present conductivities around 6 × 10-7 S.cm-1at room temperature and total ionic transference number is higher for membranes based on polymers with high EG unit content. Best results yield 88%, inherent viscosities 0.48 dl/g and Mn 26000 were obtained with 1-methylimidazole and PEG 2000. These membranes based on these polymers showed good LOI values (in the range 26-29%) and indicate an improvement of the safety of lithium batteries.

Preparation and Characterization of Novel Polyimide/SiO2 Nano-hybrid Films by In Situ Polymerization

A silicon-based aromatic polyimide (PI) containing pendent aryl rings was synthesized by solution polycondensation of a silicon-containing diamine with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride. Its nano-hybrids with different colloidal SiO2 concentrations were synthesized by in situ polymerization. The reactions were carried out in presence of 3-aminopropyltriethoxysilane as a coupling agent. The inclusion of the coupling agent in the polymer chain and its co-condensation with SiO2 nanoparticles afforded a silica network that was interconnected chemically with the PI matrix. The chemical structure of the hybrid materials was analyzed by Fourier transform infrared spectroscopy and energy dispersive X-ray spectroscopy. The morphology of the hybrid films and the surface roughness were characterized by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. The results indicated that nanometer-scale inorganic particles were homogeneously dispersed throughout the PI matrix with 50–70 nm size range. The best results and favorable miscibility between polymer and silica phases in the nano-hybrids were obtained when up to 40 wt% nanoparticles were introduced into the backbone of PI matrix.

Liquid‐crystalline azobenzene‐containing ferrocene‐based polymers: study on synthesis and properties of main‐chain ferrocene‐based polyesters with azobenzene in the side chain

Ferrocene‐based polymers are characterized by their electrochemical activity, good redox properties, thermal, photochemical stability, and liquid crystallinity, and thus they have various applications in different fields. A comprehensive investigation on the synthesis and properties of three novel main‐chain ferrocene‐based polyesters with azobenzene in the side chain (MFPAS) was carried out. The main‐chain ferrocene‐based polyester, poly(N‐phenyldiethanolamine 1,1′‐ferrocene dicarboxylate (PPFD), was synthesized via the solution polycondensation reaction of 1,1′‐ferrocenedicarbonyl chloride with phenyldiethanolamine (PDE). The novel MFPAS were synthesized via the post‐polymerization azo‐coupling reaction of PPFD with three different 4‐substituted anilines including 4‐nitroaniline, 4‐aminobenzoic acid, and 4‐aminobenzonitrile to produce 4‐nitrophenylazo‐functionalized‐PPFD (PPFD‐NT), 4‐carboxyphenylazo‐functionalized‐PPFD (PPFD‐CA), and 4‐cyanophenylazo‐functionalized‐PPFD (PPFD‐CN), respectively. All the synthesized polymers were characterized by 1H NMR spectroscopy, Fourier transform infrared spectroscopy, and UV–visible spectroscopy. In addition, powder X‐ray diffraction patterns were measured for the synthesized polymers. The photoisomerization of the MFPAS was studied. The thermal properties of the MFPAS were studied using thermogravimetric analysis and differential scanning calorimetry. PPFD‐CA and PPFD‐CN were found to be more thermally stable than PPFD‐NT. Finally, the liquid‐crystalline properties of PPFD and the MFPAS were examined using polarized optical microscope. It was found that all the polymers possessed nematic phases and exhibited textures with schlieren disclinations. Copyright © 2012 John Wiley & Sons, Ltd.