Wholly aromatic polyamide-hydrazides. IV. Structure–property relationships for polymers containing p-phenylene and m-phenylene units

A series of wholly aromatic polyamide-hydrazides was investigated in order to acquire clear understanding of the influence exerted by controlled structural variations in these polymers upon some of important properties, such as chain flexibility, membrane permselectivity, and thermal as well as thermo-oxidative stability. For that reason, the content of para and meta phenylene units was varied within this series so that the changes in the latter were 12.5 mol % from polymer to polymer, starting from an overall content of 0–50 mol %. The polymers were prepared by a low-temperature solution polycondensation reactin of p-aminobenzhydrazide (ABH) and terephthaloyl chloride (TCI), isophthaloyl chloride (ICI), and their appropriate combinations in N,N-dimethylacetamide (DMA) as solvent and all of these preparations were monitored viscometrically in order to prepare the products with as similar as possible average molecular weights. Polymer structures were characterized by elemental analysis, infrared spectrometry, and ¹³C NMR spectroscopy, while their molecular weights were determined by light scattering and dilute-solution viscometry. Polymer properties were evaluated by solution viscometry, reverse osmosis tests, and thermal gravimetric analysis. The results obtained during the preparation of these materials, their subsequent structural characterization, and their property evaluations are discussed. They clearly indicate that substitution of m-phenylene units for p-phenylene ones within this polymer series led to an increase in polymer chain flexibility (from what is usually referred to as semiflexible or semirigid to typically flexible macromolecules), disrupted selectivity of the asymmetric thin membranes under reverse osmosis conditions and decreased stability at elevated temperatures in inert as well as in oxidative atmospheres.     

Conjugated polymers containing phenothiazine moieties in the main chain

Several conjugated polymers containing phenothiazine moieties in the main chain were synthesized by Knovenagel or Wittig condensations. The polymers were identified and characterized by ¹H‐NMR, IR, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), UV‐vis and fluorescent (FL) spectra. Results indicated that the m‐polymer, which was prepared from the polycondensation of N‐octyl‐3,7‐diformylphenothiazine with m‐phenylene diacetonitrile, is the most thermally stable one in all the polymers synthesized. While, the p‐polymer, which was prepared from the polycondensation of N‐octyl‐3,7‐diformylphenothiazine with p‐phenylene diacetonitrile, is the most thermally instable one. The introduction of a cyano group made the absorption and emissive maxima red‐shift from 429 and 537 nm for the Ph‐polymer to 465 and 597 nm for the p‐polymer respectively. The quinoid structure formation allows the p‐polymer to have a lower band gap than any other polymers. Emissive spectra of all these polymers in tetrahydrofuran (THF) solution have a narrow half‐peak width. Copyright © 2006 John Wiley & Sons, Ltd.     

Characterization of diene polymers. I. Infrared and NMR studies: Nonadditive behavior of characteristic infrared bands

Extinction coefficients of the characteristic infrared bands due to isomeric structural units were measured for polybutadiene and polyisoprene in CS₂ or CCl₄ solutions and were compared with the isomer composition determined by NMR. The NMR signal assignments were made on the basis of the spectra of deutero derivatives of the polymers. In the case of polyisoprene, linear relations were obtained between the extinction coefficients and the isomer contents determined by NMR for the absorption bands at 1385 cm^?1 (characteristic of trans-1,4 units), 1376 cm^?1 (cis-1,4 units), and 889 cm^?1 (3,4 units). However, for the absorption bands at 840 cm^?1 (characteristic of cis-1,4 and trans-1,4 units), isomerized polyisoprenes did not give such a linear relationship. In polybutadiene, the extinction coefficient for the atactic 1,2 units was found to be lower than that of the syndiotactic 1,2 unit. These experimental facts lead to the conclusion that additivity of the extinction coefficients does not always hold for diene polymers. The deviation from the linear relation may be associated with regular sequences of one isomeric conformation in the chain.     

Synthesis,characterization, and properties of regioregular conjugated polymers containing quaterthiophene and an acceptor repeating units

Novel donor–acceptor type polymers consisting of alternating quaterthiophene and an electron withdrawing moiety, pyrazinyl or pyridinyl, have been prepared using Stille coupling approach with moderate yields. The polymers were highly soluble in common organic solvents such as tetrahydrofuran and chloroform. The structure and optical properties of the polymers were characterized by NMR, UV‐vis and fluorescence spectroscopy, and cyclic voltammetry, respectively. The polymer having pyrazine unit exhibited a red‐shift in both absorption and emission in comparison with those analogs containing pyridine because of strong electron withdrawing character of the pyrazinyl group. The polymer containing pyrazinyl as acceptor units also depicted decrease in its optical and electrochemical bandgap relative to those polymers containing 2,5‐ or 2,6‐pyridine moieties. The electrochemical behavior showed facile n‐doping and p‐doping properties of those polymers consisting of alternating quaterthiophene and the acceptor moiety. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2163–2171, 2009     

Stimuli-Responsive Polymers in Solution Investigated by NMR and Infrared Spectroscopy

Summary: Temperature-induced and solvent composition-induced phase separation in solutions of poly(N-isopropylmethacrylamide) (PIPMAm) and other thermoresponsive polymers as studied by NMR and infrared (IR) spectroscopy is discussed. The fraction p of phase-separated units (units with significantly reduced mobility) and subsequently, e.g., thermodynamic parameters characterizing the coil-globule phase transition induced by temperature, were determined from reduced integrated intensities in high-resolution ¹H NMR spectra. This approach can be especially useful in investigations of phase separation in solutions of binary polymer systems. Information on behaviour of water during temperature-induced phase transition was obtained from measurements of ¹H NMR relaxation times of HDO molecules. NMR and IR spectroscopy were used to investigate PIPMAm solutions in water/ethanol (D₂O/EtOH) mixtures where the phase separation can be induced by solvent composition (cononsolvency). Some differences in globular-like structures induced by temperature and solvent composition were revealed by these methods.     

Syntheses and antitumor activities of monomer and medium molecular weight polymers. III. 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidopropanoyl-5-fluorouracil and its polymers

The new monomer, 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidopropanoyl-5-fluorouracil (ETPFU), was synthesized by the reaction of 5-fluorouracil (5-FU) and 3,6-endo-methylene-1,2,3,6-tetrahydrophthalimidopropanoyl chloride (ETPC). The homopolymer of ETPFU and its copolymers with acrylic acid (AA) and vinyl acetate (VAc) were prepared by photopolymerizations. The synthesized ETPFU and polymers were identified by Fourier transfer infrared (FTIR), ¹H nuclear magnetic resonance (NMR), and ¹³C-NMR spectroscopies. The contents of ETPFU units in poly(ETPFU-co-AA) and poly(ETPFU-co-VAc) were 26 and 32 mol %, respectively. The number average molecular weights of the synthesized polymers determined by gel permeation chromatography (GPC) were in range from 8,800 to 10,700. The in vitro cytotoxicities of the samples were evaluated with mouse mammary carcinoma (FM3A), mouse leukemia (P388), and human histiocytic lymphoma (U937) as a cancer cell line and mouse liver cells (AC2F) as a normal cell line. The in vivo antitumor activities of polymers against Balb/c mice bearing the sarcoma 180 tumor cells were greater than those of 5-FU at all doses tested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2113–2120, 1999     

Synthesis and characterization of rigid functional anionic polyelectrolytes: Block copolymers and star homopolymers

Seven cyclolinear polymers bearing the tertiary‐butyl α‐(hydroxymethyl)acrylate (TBHMA) ether dimer were prepared using reversible addition–fragmentation chain transfer (RAFT) polymerization. Of the seven polymers, five were cyclolinear homopolymers of the TBHMA ether dimer with different degrees of polymerization, one was an “arm‐first” star homopolymer, and the other was an amphiphilic linear copolymer based on the positively ionizable hydrophilic 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and the TBHMA ether dimer. For comparison, two more polymers were prepared using RAFT polymerization where the TBHMA ether dimer was replaced by tertiary‐butyl methacrylate (tBuMA). In particular, an amphiphilic linear DMAEMA–tBuMA diblock copolymer and a tBuMA arm‐first star homopolymer were also synthesized. All polymers were characterized in terms of their molecular weights and composition using gel permeation chromatography and ¹H NMR spectroscopy, respectively. Subsequently, the tertiary‐butyl groups of the TBHMA ether dimer units and those of the tBuMA units were cleaved by hydrolysis to yield carboxylic acid groups. The successful removal of the tertiary‐butyl groups was confirmed using ¹H and ¹³C NMR and attenuated total reflectance‐Fourier transform infrared spectroscopies. The hydrolyzed (co)polymers exhibited pK values of the carboxylic acid groups of around 4.5, and glass transition temperatures, T_g, of around 200 °C, which were 50 °C higher than those of their nonhydrolyzed precursors. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation and properties of some water-soluble,comb-shaped,amphiphilic polymers

Water-soluble comb-shaped polymers were prepared through grafting of poly(ethylene glycol) monomethyl ethers (MPEG) onto acrylic and methacrylic ester copolymers by transesterification reactions. The grafting was alkali-catalyzed, and performed in refluxing toluene solution or in melt at 155°C. The grafting efficiency was found to be on the order of 1 graft/10 monomer units. Epoxy groups in glycidyl methacrylate copolymers were also utilized for grafting. The crude graft copolymers were purified through chromatography and characterized by NMR and IR spectroscopy. Polymers prepared from MPEG 2000 were crystalline with melting points 10–15°C lower than the MPEG used. All polymers were shown to be surface active with CMC on the order of 1.5 g/L, and surface tensions of 38–45 dyn/cm. When used as emulsifiers the graft copolymers containing bulky lipophilic ester groups (2-ethylhexyl t-butyl) gave oil-in-water (o/w) and water-in-oil (w/o) emulsions from xylene/water with higher stability than those containing straight chain ester groups (methyl nbutyl n-docecyl). The most stable emulsions were obtained by dissolving the polymers in the organic phase.     

Effect of spacer chemistry on the formation and properties of linear reversible polymers

A series of four pairs of bismaleimide and bisfuran monomers were combined to make thermally reversible linear polymers. The monomers were prepared using diamines having different spacer chemistries, n‐octyl, cyclohexyl, phenyl, and ethylenedioxy, such that a relatively constant spacer dimension among the four monomers was achieved. Heating of the bismaleimide/bisfuran couples resulted in low‐viscosity, easily processable liquids. Subsequent cooling to room temperature resulted in the formation of hard films, with the rate of hardening varying significantly within the series of compounds. The rate and degree of polymerization were determined using ¹H NMR spectroscopy and were both found to be dependent on the chemistry of the spacer group, as was the film rheology, which was measured using nanoindentation. Adhesion of the polymers was quantified by measurement of their tensile adhesive strength, and this was also found to be spacer dependent. Polymerization reversibility was verified using ¹H NMR spectroscopy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5056–5066     

A novel synthesis of acrylic acid containing polymers

A novel synthesis of linear acrylic acid containing polymers, poly(styrene-co-acrylic acid) and poly(acrylic acid), was accomplished through hydrolysis of the respective parent polymers, i.e. poly(styrene-co-methyl acrylate) and poly(methyl acrylate), with trimethylsilyl iodide under mild conditions. Combination of ¹H NMR, ¹³C NMR, FTIR, DSC and chemical titration confirms that the conversion from methoxycarbonyl to carboxyl is almost complete. This method is further successfully applied to synthesize poly-(ethyl methacrylate-co-acrylic acid) through selective hydrolysis of the methyl acrylate units in poly(ethyl methacrylate-co-methyl acrylate).     

Spacer‐length‐dependent association in polymers with multiple‐hydrogen‐bonded end groups

Herein, we investigate the influence of spacer length on the homoassociation and heteroassociation of end‐functionalized hydrogen‐bonding polymers based on poly(n‐butyl acrylate). Two monofunctional ureido‐pyrimidinone (UPy) end‐functionalized polymers were prepared by atom transfer radical polymerization using self‐complementary UPy‐functional initiators that differ in the spacer length between the multiple‐hydrogen‐bonding group and the chain initiation site. The self‐complementary binding strength (K_dim) of these end‐functionalized polymers was shown to depend critically on the spacer length as evident from ¹H NMR and diffusion‐ordered spectroscopy. In addition, the heteroassociation strength of the end‐functionalized UPy polymers with end‐functionalized polymers containing the complementary 2,7‐diamido‐1,8‐naphthyridine (NaPy) hydrogen‐bond motif is also affected when the aliphatic spacer length is too short. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Nanoporous materials based on spiroketal and spirothioketal polymers for separating methanol-toluene mixture

Organic microporous materials based on spiroketal and spirothioketal polymers were synthesized through 1,3-dioxol-forming polymerization reaction between pentaerythritol or pentaerythritol tetrathiol and different types of cyclohexa-1,4-dione derivatives. The structure of the prepared polymers was confirmed by NMR spectroscopy and molecular mass measurements. Nitrogen adsorption/desorption isotherms of the prepared polymers show a large amount of nitrogen adsorbed at low relative pressure indicating microporosity. These polymers have Brunauer Emmitt and Teller (BET) surface areas in the range from 492 (m² g⁻¹) to 685 (m² g⁻¹). The prepared polymers were found to be useful for pervaporation separation of methanol-toluene mixture with a separation factor up to 12.5 and fluxes, varying between 6.7 × 10⁻³ kg/(m² h) and 13.4 × 10⁻³ kg/(m² h).     

Preparation of hole transporting polymers by condensation polymerization of triphenylamine derivatives

Hole transporting polymers were prepared by condensation polymerization of triphenylamine and N,N,N',N'‐tetraphenylbenzidine (TPD) having alkyl group with aldehydes in the presence of p‐toluenesulfonic acid. The obtained polymers had molecular weight higher than 10,000 and good film formation ability. It was found that the aromatic amine monomers were connected with aldehyde monomer at the p‐position of the phenyl group. TPD‐aldehyde polymers had almost the same UV absorption and redox potentials as those of TPD monomer indicating that the electronic structure of amine unit did not change by the polymerization. The hole transporting mobility was in the range of 10⁻³‐10⁻⁶cm²/Vs. The electroluminescent device consisting of ITO/TPD polymer/Alq/Mg‐Ag had a maximum luminance of 9000 cd/m².     

Microstructure of polymers obtained by cationic polymerization of endo-dicyclopentadiene

endo-Dicyclopentadiene (DCPD) was polymerized by various cationic initiating systems in different solvents. IR and ¹H NMR results show that four types of structural units are formed due to the corresponding addition modes: the addition on the norbornenic (NB) double bond generates unit I and rearranged unit II, while the addition on the cyclopentenic (CP) double bond produces unit III and rearranged unit IV. The reaction medium has a stronger effect on the microstructure of the polymer (PDCPD) than initiating systems. The polymers prepared in toluene and n-hexane contain all four structural units, while the polymer produced in methylene chloride is composed of structural units II and IV. © 1996 John Wiley & Sons, Inc.     

Novel highly soluble 3,3′-bicarbazolyl based polymers for optoelectronics

Novel family of highly soluble polymers containing 3.3′-bicarbazolyl moieties is reported. Utilizing simple and efficient chemical oxidation of carbazole and its derivatives by iron trichloride exclusively and quantitatively yields the bicarbazolyl dimmers with reactive oxirane groups. The polymers were prepared in polyaddition reaction of bicarbazolyl-containing diepoxydes with 4,4′-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiadiazole, or 1,3-benzenedithiol in the presence of catalyst triethylamine. Obtained compounds were characterized using GPC, DSC, IR, UV, fluorescence and ¹H NMR spectroscopy. The hole drift mobility reaches 10⁻⁴ cm²/Vs at high electric fields. Such processable polymers with conjugated-nonconjugated repeating units in the main chain and good charge carrier mobility are quite promising for fabrication of optoelectronic devices.     

Head to head polymers. XVII: Head to head polypropylene

Head to head polypropylene was prepared by catalytic hydrogenation of eithercis-1,4-poly(2,3-dimethylbutadiene) ortrans-1,4-poly(2,3-dimethylbutadiene) with cobalt 2-ethylhexanoate/triethylaluminium as the hydrogenation catalyst in decahydronaphthalene solution. The hydrogenation occurred predominantly bycis hydrogen addition, but was not stereospecific. The samples of head to head polypropylene were characterized by IR and NMR, particularly by¹³C-NMR spectroscopy. The polymers were amorphous and exhibited glass transition temperatures about 20°C lower than that of head to tail poly-propylene; the glass transition temperatures were measured by DSC and varied somewhat from sample to sample (sufficiently high molecular weight) according to their stereochemistry. TheT _gvalues were confirmed by Rheovibron measurements. The thermal stability of head to head polypropylene is not significantly different from that of either atactic or isotactic head to tail polypropylene.Part XVI:Grossman S., Yamada A., Vogl O., J. Macromol. Sci.-Chem.A 16, 897 (1981).     

Silicon surface modification with trialkoxysilyl‐functionalized star‐shaped polymers

The synthesis of trimethoxysilane end‐capped linear polystyrene (PS) and star‐branched PS and subsequent silicon (Si) surface modification with linear and star polymers are described. Trimethoxysilane terminated PS was synthesized using sec‐butyl lithium initiated anionic polymerization of styrene and subsequent end‐capping of the living anions with p‐chloromethylphenyl trimethoxysilane (CMPTMS). ¹H and ²⁹Si NMR spectroscopy confirmed the successful end‐capping of polystyryllithium with the trimethoxysilane functional group. The effect of a molar excess of end‐capper on the efficiency of functionalization was also investigated, and the required excess increased for higher molar mass oligomers. Acid catalyzed hydrolysis and condensation of the trimethoxysilane end‐groups resulted in star‐branched PS, and NMR spectroscopy and SEC analysis were used to characterize the star polymers. This is the first report of core‐functionalized star‐shaped polymers as surface modifiers and the first comparative study showing differences in surface topography between star and linear polymer modified surfaces. Surface‐sensitive techniques such as ellipsometry, contact angle goniometry, and AFM were used to confirm the attachment of star PS, as well as to compare the characteristics of the star and linear PS modified Si surfaces. The polymer film properties were referenced to polymer dimensions in dilute solution, which revealed that linear PS chains were in the intermediate brush regime and the star‐branched PS produced a surface with covalently attached chains in the mushroom regime. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3655–3666, 2005     

NEW BLUE CROSSLINKABLE POLYMERS FOR ORGANIC LIGHT EMITTING DEVICES

Here, we report on new blue electroluminescence (EL) crosslinkable polymers containing fluorene/phenylene alternating repeating units. Additionally, they contain polymerizable oxetane groups attached through flexible hexyloxy chains to phenylene units of the polymer backbone. The copolymers were synthesized via Pd-catalyzed Suzuki coupling reactions. The copolymers obtained were found to be soluble and easily processable from common organic solvents such as chloroform or toluene and have been characterized by ¹H and ¹³C NMR spectroscopy, FT-IR spectroscopy and elemental analysis. The degree of polymerization has been determined by gel permeation chromatography (GPC). The thermal properties of the copolymers have been characterized by differential scanning calorimetry (DSC). The optical properties of the polymers were investigated in solution by UV/VIS spectroscopy. The polymers were photo-crosslinked in spin-coated thin films to yield insoluble networks.     

Substituent effect on azobenzene‐based liquid‐crystalline organophosphorus polymers

An Erratum has been published for this article in Journal of Polymer Science Part A: Polymer Chemistry (2003) 41(23) 3862 A new series of combined‐type, azobenzene‐based organophosphorus liquid‐crystalline polymers were synthesized, and their photoisomerization properties were studied. The prepared polymers contained azobenzene units as both the main‐chain and side‐chain mesogens. Various groups were substituted in the terminal of the side‐chain azobenzene mesogen, and the effects of the substituents were investigated. All the polymers were prepared at the ambient temperature by solution polycondensation with various 4‐substituted phenylazo‐4′‐phenyloxyhexylphosphorodichloridates and 4,4′‐bis(6‐hydroxyhexyloxy) azobenzene. The polymers were characterized with gel permeation chromatography, Fourier transform infrared, and ¹H, ¹³C, and ³¹P NMR spectroscopy. Thermogravimetric analysis revealed that all the polymers had high char yields. The liquid‐crystalline behavior of the polymers was examined with hot‐stage optical polarizing microscopy, and all the polymers showed liquid‐crystalline properties. The formation of a mesophase was confirmed by differential scanning calorimetry (DSC). The DSC data suggested that mesophase stability was better for electron‐withdrawing substituents than for halogens and unsubstituted ones. Ultraviolet irradiation studies indicated that the time taken for the completion of photoisomerization depended on the dipolar moment, size, and donor–acceptor characteristics of the terminal substituents. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3188–3196, 2003     

Click polymerization: Synthesis of novel σ-π conjugated organosilicon polymers

Poly[silylene-1,4-phenylene-(1,2,3-triazol-4-yl)-1,4-phenylene]s were prepared via step-growth Click coupling polymerization of bis(p-ethynylphenyl)silanes and 1,4-diazidobenzene. The organosilicon units in the backbones may contribute to an electronic communication among the π-conjugated units and improve the solubility of the polymers. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR) were used to confirm the polymers structure. The UV-vis absorption wavelength of silicon-containing compounds red-shifted ca. 15 nm when compared with the compounds without silicon atoms. The fluorescence emission of polymers in CHCl₃ solutions was observed in visible blue region (ca. 440 nm), and the intensity and quantum yield (Φ) were enhanced due to the influence of σ-π interaction. The results of the absorption and emission supported the weak σ-π conjugation between the silylene and aromatic segments, and these polymers can be potentially applied in organic light emitting devices (OLEDs).