A fluorescent chemosensor based on optically active 2,2′‐binaphtho‐20‐crown‐6 for metal ions

A chiral conjugated polymer can be obtained by the polymerization of (S)‐6,6′‐dibromo‐2,2′‐binaphtho‐20‐crown‐6 and 1,4‐divinyl‐2,5‐dibutoxybenzene via a palladium‐catalyzed Heck cross‐coupling reaction. The chiral conjugated polymer shows strong green‐blue fluorescence. The responsive properties of the chiral polymer to metal ions were investigated using fluorescence and UV‐visible absorption spectra. K⁺, Pb²⁺, Cd²⁺ and Ba²⁺ enhance the fluorescence of the polymer; in contrast, Hg²⁺ causes effective quenching of the fluorescence of the polymer. The obvious influences on the fluorescence indicate that the 2,2′‐binaphtho‐20‐crown‐6 moiety plays an important role in fluorescence recognition for Hg²⁺ due to the effective photo‐induced electron transfer or charge transfer between the conjugated polymer backbone and the receptor ions. The responsive properties of the polymer to metal ions show that the chiral conjugated polymer incorporating 2,2′‐binaphtho‐20‐crown‐6 moieties in the main‐chain backbone as recognition sites can act as an excellent fluorescent probe for the sensitive detection of Hg²⁺. Copyright © 2010 Society of Chemical Industry     

Synthesis and adsorption properties for metal ions of mesocyclic diamine‐grafted chitosan‐crown ether

A new type of grafted chitosan‐crown ether was synthesized using mesocyclic diamine crown ether as the grafting agent. The C2 amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N‐benzylidene chitosan (CTB). After reaction with mesocyclic diamine crown ether of the epoxy propane group to give mesocyclic diamine‐N‐benzalidene chitosan (CTBA), the Schiff base was removed in a dilute ethanol hydrochloride solution to obtain chitosan‐crown ether (CTDA). Its structure was confirmed by FTIR spectra analysis and X‐ray diffraction analysis. Its static adsorption properties for Pb(II), Cu(II), Cd(II), and Cr(III) were studied. The experimental results showed that the grafted chitosan‐crown ether has high selectivity for the adsorption of Cu(II) in the presence of Pb(II), Cu(II), and Cd(II) and its adsorption selectivity is better than that of chitosan. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1255–1260, 2000     

Synthesis and photophysical behavior of a water‐soluble coumarin‐bearing polymer for proton and Ni2+ ion sensing

BACKGROUND: In recent years, many fluorescent chemosensors with various macromolecular structures have been prepared for the detection of protons or metal cations in the environment. Most of this research is focused on polymer sensors with fluorescent recognition sites in the main chain. In this case, the fluorescent recognition sites are covalently bonded to the polymer chain, and thus the polymer shows photophysical properties as a chemosensor for protons and metal ions. RESULTS: An acrylic monomer bearing coumarin moieties, 7‐hydroxy‐4‐methyl‐8‐(4′‐acryloylpiperazin‐1′‐yl)methylcoumarin, was synthesized. This was then copolymerized with N‐vinylpyrrolidone to obtain a blue fluorescent material. The fluorescent copolymer has good solubility in aqueous solution. Its main photophysical properties were determined in relation to its use as a sensor for protons and metal cations. It is an efficient ‘off‐on’ switcher for pH between 3.02 and 12.08. Additionally, the polymer sensor is selective to Ni²⁺ ions, with the increase in the fluorescence intensity depending on Ni²⁺ ion concentrations in the range 0.33 × 10^?5–7.67 × 10^?5 mol L^?1. CONCLUSION: The results suggest that this copolymer may offer potential as a reusable polymer sensor for protons and Ni²⁺ ions in aqueous solution. Copyright © 2009 Society of Chemical Industry     

Study of the synthesis of chitosan derivatives containing benzo‐21‐crown‐7 and their adsorption properties for metal ions

Three new chitosan crown ethers, N‐Schiff base‐type chitosan crown ethers (I, III), and N‐secondary amino type chitosan crown ether (II) were prepared. N‐Schiff base‐type chitosan crown ethers (I, III) were synthesized by the reaction of 4′‐formylbenzo‐21‐crown‐7 with chitosan or crosslinked chitosan. N‐Secondary amino type chitosan‐crown ether (II) was prepared through the reaction of N‐Schiff base type chitosan crown ether (I) with sodium brohydride. Their structures were characterized by elemental analysis, infrared spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. In the infrared spectra, characteristic peaks of C?N stretch vibration appeared at 1636 cm^?1 for I and 1652 cm^?1 for II; characteristic peaks of N? H stretch vibration appeared at 1570 cm^?1 in II. The X‐ray diffraction analysis showed that the peaks at 2θ = 10° and 28° disappeared in chitosan derivatives I and III, respectively; the peak at 2θ = 10° disappeared and the peak at 2θ = 28° decreased in chitosan‐crown ether II; and the peak at 2θ = 20° decreased in all chitosan derivatives. In the solid‐state ¹³C NMR, characteristic aromatic carbon appeared at 129 ppm in all chitosan derivatives, and the characteristic peaks of carbon in C?N groups appeared at 151 ppm in chitosan crown ethers I and III. The adsorption and selectivity properties of I, II, and III for Pd²⁺, Au³⁺, Pt⁴⁺, Ag⁺, Cu²⁺, and Hg²⁺ were studied. Experimental results showed these adsorbents not only had good adsorption capacities for noble metal ions Pd²⁺, Au³⁺, Pt⁴⁺, and Ag⁺, but also high selectivity for the adsorption of Pd²⁺ with the coexistence of Cu²⁺ and Hg²⁺. Chitosan‐crown ether II only adsorbs Hg²⁺ and does not adsorbs Cu²⁺ in an aqueous system containing Pd²⁺, Cu²⁺, and Hg²⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1886–1891, 2002     

Synthesis of poly(4‐aminophenol) by horseradish peroxidase and the evaluation of its adsorptivity for silver ions

In this study, poly(4‐aminophenol) was successfully prepared by an enzymatic reaction in water, with its molecular weights ranging from 12,000 to 52,000. The polymerization of 4‐aminophenol produced high yields over a wide pH ranging from 4 to 10. In addition, poly(4‐aminophenol) was also used for silver‐ion adsorption because it was composed of amino and hydroxyl groups. We found that the adsorption capacity of poly(4‐aminophenol) was relevant to the time, pH value, temperature, and concentration of silver ions, and the greatest adsorption capacity of poly(4‐aminophenol) for silver ions was 220 mg/g. Moreover, a series of tests showed that the adsorption of silver ions was mainly achieved by a reduction reaction, and the silver nanoparticles were formed with a face‐centered cubic structure, and their average particle size was about 10 nm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40367.     

Applications of wittig reactions in dibenzo 18‐crown‐6‐ether substituted phenylenevinylene oligomer—synthesis,photo luminescent,and dielectric properties

Novel phenylenevinylene oligomer substituted dibenzo 18‐crown‐6 ether ring (DB‐OPV) was synthesized using dibenzo 18‐crown‐6 with terephthaldicarboxaldehyde via Wittig reaction. Formation of the oligomer was confirmed by spectral (FT‐IR, ¹H and¹³C‐NMR), gel‐permeation chromatography and elemental analysis. The morphology of the oligomer film of one‐dimensional and three‐dimensional architectures was observed using atomic force microscopy. The oligomer showed excellent photoluminescence with bluish green emission maxima at shorter wavelengths of 505 nm. Stability of the oligomer was analyzed using UV spectroscopy with varying time and temperature. The dielectric properties such as dielectric constant and loss factor for the oligomer have also been studied with respect to change of frequency (50 Hz–5 MHz) and temperature (30–60°C). The value of dielectric constant decreased with increasing frequency, which indicates that the major contribution to the polarization comes from orientation polarization. The value of dielectric constant increased with increasing temperature which is due to greater freedom of movement of the dipole molecular chains within the oligomer at high temperature © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fluorescent chemosensor based on the conjugated polymer incorporating 2,2′‐bipyridyl moiety for transition metal ions

A fluorescent conjugated polymer was synthesized by the polymerization of 1,4‐dibromo‐2,3‐bisbutoxynaphthalene ( M‐2 ) with 5,5′‐divinyl‐2,2′‐bipyridine ( M‐3 ) via Heck reaction. The conjugated polymer shows strong blue–green fluorescence because of the extended π‐electronic structure between the repeating unit 2,3‐bisbutoxynaphthyl group and the conjugated linker 2,2′‐bipyridyl (bpy = 2,2′‐bipyridine) moiety via vinylene bridge. The responsive properties of the conjugated polymer on transition metal ions were investigated by fluorescent and UV–vis spectra. The results show that Cu²⁺ and Ni²⁺ can form nonradiative metal‐to‐ligand charge‐transfer complexes with the polymer, whereas, Zn²⁺ and Cd²⁺ do not produce the pronounced differences from the polymer fluorescence and UV–vis spectra. The fluorescent quenching can probably be attributed to the intramolecular photoinduced electron transfer (PET) or photoinduced charge transfer (PCT). The results can also suggest that 2,2′‐bipyridyl moiety in the main chain backbone of the conjugated polymer can act as the recognition site of a special fluorescent chemosensor for sensitive detection of transition metal ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Galvanic deposition of silver on 80‐μm‐Cu‐fiber for gas‐phase oxidation of alcohols

Microstructured Ag‐based catalysts were developed by galvanically depositing Ag onto 80‐μm‐Cu‐fibers for the gas‐phase oxidation of alcohols. By taking advantages including large voidage, open porous structure and high heat/mass transfer, as‐made catalysts provided a nice combination of high activity/selectivity and enhanced heat transfer. The best catalyst was Ag‐10/80‐Cu‐fiber‐400 (Ag‐loading: 10 wt%; Cu‐fiber pretreated at 400 °C in air), being effective for oxidizing acyclic, benzylic and polynary alcohols. For benzyl alcohol, conversion of 94% was achieved with 99% selectivity to benzaldehyde at 300 °C using a high WHSV of 20 h^?1. Computational fluid dynamics (CFD) calculation and experimental result illustrated significant enhancement of the heat transfer. The temperature difference from reactor wall to central line was about 10–20 °C for the Ag‐10/80‐Cu‐fiber‐400, much lower than that of 100–110 °C for the Ag‐10‐Cu‐2/Al₂O₃ at equivalent conversion and selectivity. Synergistic interaction between Cu₂O and Ag was discussed, being assignable to the activity improvement. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1045–1053, 2014     

Organosoluble and light‐colored fluorinated polyimides based on 1,1‐bis[4‐(4‐amino‐2‐trifluoromethylphenoxy)phenyl]‐1‐phenylethane and various aromatic dianhydrides

To investigate the CF₃ group affecting the coloration and solubility of polyimides (PI), a novel fluorinated diamine 1,1‐bis[4‐(4‐amino‐2‐ trifluoromethylphenoxy)phenyl]‐1‐phenylethane (2) was prepared from 1,1‐ bis(4‐hydrophenyl)‐1‐phenylethan and 2‐chloro‐5‐nitrobenzotrifluoride. A series of light‐colored and soluble PI 5 were synthesized from 2 and various aromatic dianhydrides 3a–f using a standard two‐stage process with thermal 5a– f(H) and chemical 5a–f(C) imidization of poly(amic acid). The 5 series had inherent viscosities ranging from 0.55 to 0.98 dL/g. Most of 5a–f(H) were soluble in amide‐type solvents, such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐ dimethylacetamide (DMAc), and N,N‐dimethylformamide (DMF), and even soluble in less polar solvents, such as m‐Cresol, Py, Dioxane, THF, and CH₂Cl₂, and the 5(C) series was soluble in all solvents. The GPC data of the 5a–f(C) indicated that the Mn and Mw values were in the range of 5.5–8.7 × 10⁴ and 8.5–10.6 × 10⁴, respectively, and the polydispersity index (PDI) Mw /Mn values were 1.2–1.5. The PI 5 series had excellent mechanical properties. The glass transition temperatures of the 5 series were in the range of 232–276°C, and the 10% weight loss temperatures were at 505–548 °C in nitrogen and 508–532 °C in air, respectively. They left more than 56% char yield at 800°C in nitrogen. These films had cutoff wavelengths between 356.5–411.5 nm, the b* values ranged from 5.0–71.1, the dielectric constants, were 3.11–3.43 (1MHz) and the moisture absorptions were in the range of 011–0.40%. Comparing 5 containing the analogous PI 6 series based on 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐1‐ phenylethane (BAPPE), the 5 series with the CF₃ group showed lower color intensity, dielectric constants, and better solubility. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2399–2412, 2005     

Synthesis and characterization of novel aromatic ether nitrile monomer containing propenylphenoxy groups and properties of its copolymer with 4,4′‐bismaleimidodiphenylmethane

A novel aromatic ether nitrile monomer containing propenyl groups, 2,6‐di{2‐[(E)‐1‐propenyl]phenoxy} benzonitrile (DPPB), was synthesized by the reaction of 2,6‐dichlorobenzonitrile and 2‐allylphenol using anhydrous potassium carbonate as the acid acceptor, N‐methyl pyrrolidone as the dipolar aprotic solvent, and toluene as the dehydrating agent. The chemical structure of DPPB was characterized by FTIR and ¹H‐NMR. The monomer was used to modify a popular commercial bismaleimide, 4,4‐bismaleimidodiphenylmethane (BMDPM), to improve the shear strength of the resin. The results showed that DPPB could effectively improve the shear strength of the BMDPM resin without decreasing the heat resistance of BMDPM. A better result was obtained when the composition of DPPB in the copolymer was 45 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1465–1472, 2002     

Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene‐containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups

A series of novel organosoluble and light‐colored fluorinated poly(ether imide)s (PEIs) ( IV ) having inherent viscosities of 0.43–0.59 dL/g were prepared from 4,4′‐[1,4‐phenylenbis(isopropylidene‐1,4‐phenyleneoxy)]diphthalic anhydride ( I ) and various trifluoromethyl‐substituted aromatic bis(ether amine)s by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution‐cast into transparent and tough films. These films were essentially colorless, with an UV–visible absorption edge of 361–375 nm and a very low b* value (a yellowness index) of 15.3–17.0. They also showed good thermal stability with glass‐transition temperature of 191–248°C, 10% weight loss temperature in excess of 494°C, and char yields at 800°C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83–96 MPa, elongations at break of 8–11%, and initial moduli of 1.7–2.0 GPa. They possessed lower dielectric constants of 3.25–3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 620–628, 2007     

Multicarboxylic aromatic acid core initiator for the synthesis of star‐shaped poly(ϵ‐caprolactone) with carboxyl end groups

We successfully carried out the ring‐opening polymerization of ?‐caprolactone with 1,3,5‐benzenetricarboxylic acid and 1,2,4,5‐benzenetetracarboxylic acid as the core initiators at 225°C in bulk, and three‐armed and four‐armed star poly(?‐caprolactone)s [poly(?‐CL)s] with carboxyl end groups were obtained. No transesterification, which would have led to a decrease in the molecular weight of poly(?‐CL), was found. The effects of the polymerization conditions on the polymerization are discussed; the poly(?‐CL)s were characterized by ¹H‐NMR, gel permeation chromatography, and thermogravimetric analysis in detail. A mechanism of alkyl–oxygen bond scission by the nucleophilic attack of the carboxyl anions via hydrogen proton transfer is presented for this system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3713–3717, 2006     

Preparation and characterisation of a novel copper‐imprinted polymer based on β‐cyclodextrin copolymers for selective determination of Cu2+ ions

A novel ion‐imprinted polymer (IIP) using (6‐O‐butene diacid ester)‐β‐cyclodextrin (β‐CD‐MAH) as the functional monomer and copper ions as the template was developed for Cu²⁺ sensing. First, reactive β‐cyclodextrin (β‐CD) monomers with vinyl carboxylic acid functional groups were synthesised and were co‐polymerised with styrene via radical polymerisation. Then, the β‐CD copolymers were complexed with Cu²⁺ in order to obtain the IIP. The imprinting effect was realised by removing the template ions from the imprinted polymer. The structure, composition and morphology of the IIP were characterised by Fourier transform IR spectroscopy, energy‐dispersive spectroscopy and field‐emission SEM. The adsorption capacity was investigated by UV–visible spectroscopy in batch operation mode. The maximum adsorption capacity for the Cu²⁺ template ions was 28.91 mg g^?1, and the adsorption selectivity was clearly illustrated from the increased sorption affinity towards Cu²⁺ ions over other competing ions. The adsorption was affected by the pH of the aqueous medium, and enhanced adsorption capacity was observed at pH 5. The prepared IIP could be used 10 times after its regeneration without significant loss of the adsorption capacity. © 2018 Society of Chemical Industry     

Cd2+, Cu2+, Pb2+, Sr2+, and Y3+ binding characteristics of 17β‐estradiol molecularly imprinted polymer particles incorporated with dicyclohexano‐18‐crown‐6 for urine bioassay

The metal ion binding characteristics of molecularly imprinted polymer (MIP) submicron particles prepared using 17β‐estradiol (E2) as a template, and incorporated with dicyclohexano‐18‐crown‐6 (DCH18C6), were studied using differential pulse anodic stripping voltammetry. When Sr²⁺ was added to DCH18C6‐E2‐MIP particles already occupied by Cd²⁺, Cu²⁺, and Pb²⁺ inside the binding sites, a displacement reaction was observed: Cd²⁺/Cu²⁺/Pb²⁺‐DCH18C6‐E2‐MIP + Sr²⁺ = Sr²⁺‐DCH18C6‐E2‐MIP + Cd²⁺/Cu²⁺/Pb²⁺. This demonstrated that DCH18C6 had stronger binding affinity for Sr²⁺ than Cd²⁺ Cu²⁺ or Pb²⁺. Strong DCH18C6 binding affinity was also observed for Y³⁺. Atomic emission spectrometry showed that DCH18C6‐E2‐MIP particles (150 mg/mL) resulted in 52% binding of Sr²⁺ (2000 ppm, at pH 6.3 ± 0.1 and ionic strength of 0.1M NaNO₂). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of chemical compositions on the properties of random and multiblock sulfonated poly(arylene ether sulfone)‐based proton‐exchange membranes

The influence of chemical compositions on the properties of sulfonated poly(arylene ether sulfone)‐based proton‐exchange membranes was studied. First, we synthesized three different series of random SPAES copolymers using three kinds of hydrophobic monomers, including 4,4′‐dihydroxyldiphenylether, 2,6‐dihydroxynaphthalene (DHN), and 4,4′‐hexafluoroisopropylidenediphenol (6F‐BPA) to investigate effects of hydrophobic components on the properties of SPAES membranes as proton‐exchange membranes. Random SPAES copolymers with 6F‐BPA showed the highest proton conductivity while random SPAES copolymers with DHN displayed the lowest methanol permeability among the three random copolymers. Subsequently, we synthesized multiblock SPAES using the DHN as a hydrophobic monomer and studied the effect of the length of hydrophilic segments in the multiblock SPAES copolymers on membrane performance. The results indicated that longer hydrophilic segments in the copolymers led to higher water uptake, proton conductivity, and proton/methanol selectivity of membranes even at low humidity. In addition, the morphology studies (AFM and SAXS measurements) of membranes suggested that multiblock copolymers with long hydrophilic segments resulted in developed phase separation in membranes, and ionic clusters formed more easily, thus improving the membrane performance. Therefore, both the kinds of hydrophobic monomers and the length of hydrophilic segments in SPAES copolymers would influence the membranes performance as proton‐exchange membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Detection of heavy metal ions using a water‐soluble conjugated polymer based on thiophene and meso‐2,3‐dimercaptosuccinic acid

This work reports the synthesis of a new water‐soluble conjugated polymer, which interacts specifically with heavy metal ions such as lead and mercury. In order to produce such a material, the fluorescent properties of polythiophene, which constitutes the polymer backbone, were combined with the chelating capacity of meso‐2,3‐dimercaptosuccinic acid, which forms the side‐chain of the conjugated polymer. Thus, the new polymer acts as chemical complexing agent, the fluorescence of which is quenched in the presence of heavy metal ions. A possible explanation of the mechanism of such a variation is also discussed. The system presented is envisaged to be used as a sensor for heavy metal ions that appear as pollutants in the environment .     

Nanostructured membranes based on sulfonated poly(aryl ether sulfone) and silica for fuel‐cell applications

Nanostructured sulfonated poly(aryl ether sulfone) (SPSU) membranes were made from SPSU/silica composites through the addition of amorphous, precipitated, and micronized silica particles (Tixosil 333) and short or segmented linear structures. Linear and branched segments of silica were obtained from the in situ reaction of tetraethoxysilane (TEOS) in an SPSU solution through a sol–gel acid‐catalyzed process. Different amounts of silica in the SPSU composites were prepared to evaluate their influence on the ionic conductivity, the water and alcohol solution sorption capacities, and the stability in an ethanol medium. The effect of silica (Tixosil) on the conductivity was higher than that of the silica made from TEOS in SPSU composites. The conductivities of the membranes containing 10% Tixosil and 6.6% silica prepared from TEOS were measured at 80°C; their values were 60 and 33 mS/cm, respectively. Furthermore, a membrane made of a silica blend (5% Tixosil and 3% TEOS) in SPSU attained a value of 92 mS/cm, whereas the commercial membrane Nafion 117, used as a reference, had a conductivity of 54 mS/cm measured under the same conditions. All those composites membranes could be used as components in hydrogen fuel cell. However, only the SPSU/2% Tixosil composite could be used in both hydrogen and ethanol direct fuel cells. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of soluble poly(arylene ether ketone)s with high glass transition temperature based on 3,6‐bi(4‐fluorobenzoyl)‐N‐alkylcarbazole

3,6‐bi(4‐fluorobenzoyl)‐N‐methylcarbazole and 3,6‐bi(4‐fluorobenzoyl)‐N‐ethylcarbazole were synthesized and used to prepare poly(arylene ether ketone)s (PAEKs) with high glass transition temperatures (T_g) and good solubility. High molecular weight amorphous PAEKs were prepared from these two difluoroketones with hydroquinone, phenolphthalein, 9,9‐bis(4‐hydroxyphenyl)fluorene and 4‐(4‐hydroxylphenyl)‐2,3‐phthalazin‐1‐one, respectively. All these polymers presented high thermal stability with glass transition temperatures being in the range 239–303 °C and a 5% thermal weight loss temperature above 460 °C. Compared with the T_g of phenolphthalein‐based PAEK (PEK‐C), fluorene‐based PAEK (BFEK) and phthalazinone‐based PAEK (DPEK) not containing a carbazole unit, these polymers presented a 30–50 °C increase in T_g. Meanwhile, PAEKs prepared from N‐ethylcarbazole difluoroketone showed good solubility in ordinary organic solvents, and all polymers exhibited excellent resistance to hydrochloric acid (36.5 wt%) and sodium hydroxide (50 wt%) solutions. In particular, phthalazinone‐based PAEK bearing N‐ethylcarbazole afforded simultaneously a T_g of 301 °C with good solubility. Tensile tests of films showed that these polymers have desirable mechanical properties. The carbazole‐based difluoroketones play an important role in preparing soluble PAEKs with high T_g by coordinating the relationship between chain rigidity resulting from the carbazole unit and chain distance from the side alkyl. © 2014 Society of Chemical Industry     

Synthesis and characterization of azo‐based methacrylate polymers with methoxy and nitro end groups for nonlinear optical applications

One new and three already described azobased methacrylate monomers with methoxy and nitro end groups and spacer length 2 and 6 were synthesized. These monomers were copolymerized with methyl methacrylate and the monomers as well as copolymers were characterized by classical spectroscopy techniques (FTIR, NMR, and UV‐VIS), gel permeation chromatography (GPC), elemental analysis and thermal analysis (TGA and DSC). The glass transition temperature of the polymers was found to be above room temperature and thermal decomposition temperatures above 100°C. All the polymers were amorphous in nature and formed excellent homogeneous films with good optical transparency. The polymer films coated on indium tin oxide glass slides were poled and their order parameters were calculated to check the stability of oriented dipoles. Few samples were also studied for their second harmonic generation properties. Temporal stability, checked up to 120 h at room temperature, was found to be quite satisfactory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3497–3504, 2007