Ionic liquid mediated surface micropatterning of polymer blends

A polymer of intrinsic porosity (i.e., PIM‐1) has been blended with different ionic liquids (ILs) in order to evaluate the effect of the ILs on the microstructure of the polymer blend. [C₈MIM][Cl], [BMIM][DCa], [BMPyr][DCa], and [BMIM][Tf₂N] have been selected and were mixed with PIM‐1. Polymer blends containing up to 80 wt % of ILs were prepared by a casting method with chloroform as solvent. SEM images show that during the film formation a structuring of the surface appears depending on the nature and the concentration of ILs, with appearance of well‐defined microstructure in the case of [BMIM][Tf₂N] and [BMIM][DCa]. In the case of [BMIM][Tf₂N]/PIM‐1 film, the lower IL concentration induces the denser film with small micropatterns onto the surface. AFM analysis indicates that the ILs are well dispersed on the surface. X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and water contact angle measurements show that a gradient of IL concentration is observed across the film thickness. It is demonstrated that ILs are versatile co‐solvents for inducing controlled micropatterns in polymer membrane surfaces. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46109.     

Synthesis and characterization of proton conducting polymer electrolyte based on poly(N‐vinyl pyrrolidone)

This work aims at developing and characterizing a proton conducting polymer electrolyte based on Poly(N‐vinyl pyrrolidone) (PVP) doped with ammonium bromide (NH₄Br). Proton conducting polymer electrolytes based on PVP doped NH₄Br in different molar ratios have been prepared by solution casting technique using distilled water as solvent. The XRD pattern confirms the dissociation of salt. The FTIR analysis confirms the complex formation between the polymer and the salt. The conductivity analysis shows that the polymer electrolyte with 25 mol % NH₄Br has the highest conductivity equal to 1.06 × 10^?3 S cm^?1 at room temperature. Also it has been observed that the activation energy evaluated from the Arrhenius plot is low (0.50 eV) for 25 mol % NH₄Br doped polymer electrolyte. The influence of salt concentration on dc conductivity and activation energy of the polymer electrolyte has been discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Correlation of swelling and crosslinking density with the composition of the reacting mixture employed in radical crosslinking copolymerization

This article reports the scaling laws relating the synthesis conditions with the crosslinking density (ν_e) and swelling degree (S) of poly(N‐vinylimidazole) hydrogels (PVI) prepared by radical crosslinking copolymerization in aqueous solution, with N,N′‐methylene bisacrylamide (BA) as crosslinker. Multiple linear regression of ν_e versus BA concentration ([BA]) and total comonomers concentration (C_T) in double log scale render the scaling law ν_e ～ C × [BA]^1.04 as comparable to that predicted by the model of polymer network with pendant vinyl groups (ν_e ～ C_T × [BA]), and showing inverse dependence on C_T to that expected, following from stoichiometry, for an ideal network (ν_e ～ 2[BA]/C_T). S scales with ν_e through a solvent‐dependent exponent ranging from ?0.46 to ?0.54, only slightly over the value predicted by the Flory–Rehner theory (?0.6) or the blob's model by de Gennes (?0.5 to ?0.8). Finally, the scaling law of S with the composition of the reacting mixture is also solvent‐dependent and it seems to result not only from the dependence of ν_e on C_T and [BA] but also from that of v_2r, the polymer volume fraction in the reference state, and χ, the polymer–solvent interaction parameter. Models used seem to overestimate the contribution of entanglements to the effective crosslinking density of PVI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 263–269, 2007     

Spectroscopic and electrochemical studies on block‐polymer/PMMA blend based composite polymer electrolytes

Poly(methylmethacrylate)(PMMA)/oxymethylene‐linked polyoxyethylene multi‐block polymer(Om‐POE_n, where n represents number of unit  CH₂CH₂O ) blend based composite electrolyte films containing different lithium salt concentration and nanofillers' content are prepared using solvent evaporation technique. The interaction of polymer–salt complex has been confirmed using FTIR spectral studies. The figuration of CPE was studied by XRD. Ionic conductivity and thermal behavior of the CPEs were studied with various salt concentrations, temperature, and nanofillers' content. The surface structure of the CPE is also investigated using scanning electron microscopy. The high room temperature ionic conductivity, transmittivity in the visible region, and thermal stability make these CPEs potential candidates as solid‐like electrolytes for electrochemical devices. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Interfacial properties between ionic-liquid-based electrolytes and lithium-ion-battery separator

For lithium salts, ionic liquids (ILs) are promising alternatives to conventional solvents in lithium-ion batteries (LIBs) due to a more favorable high-voltage operating window, and due to improved safety through reduction of flammability. Toward better understanding of wetting properties of IL-based electrolytes on a LIB separator, wetting properties affect electrochemical performance, experimental studies were made to determine the influence of solvent, lithium-salt type and salt concentration. Surface tensions and advancing contact angles were measured for two pure ILs ([C₄C₁im][BF₄] and [C₄C₁im][OTf]) and for four IL/alkylcarbonate solvent blends (1:1 mass ratio, [C₄C₁im][BF₄]/PC, [C₄C₁im][BF₄]/DMC, [C₄C₁im][OTf]/PC, and [C₄C₁im][OTf]/ DMC) with several concentrations of a lithium salt (LiClO₄, LiPF₆, and LiTFSI). A significant improvement of wettability of pure ILs was observed by adding DMC, while adding PC with surface tension higher than that of pure ILs is detrimental to wetting behavior. Contact angles decrease by adding LiTFSI but show almost no change upon addition of LiPF₆ or LiClO₄. Surface tensions follow the same trend as that for contact angles. Incorporation of TFSI⁻ anion gives favorable separator wettability. Estimates were made for interfacial properties of the separator (dispersive and polar components of the surface free energy for solid-vapor, for liquid–vapor, and for solid–liquid interfacial free energy).     

Kinetic investigations of the electrochemical bromination of peracetylated d-glucal in organic solvents

Cyclic voltammetry and ultramicroelectrodes were used to investigate the kinetic aspects of the electrochemical bromination of 3,4,6-tri-O-acetyl-d-glucal (1) in acetonitrile (AN), dichloromethane (DCM), and dimethylsulfoxide (DMSO). Qualitative and quantitative results, determined notably from the kinetic parameter [glucal]/v representing the competition between glucal concentration and time, clearly showed that glucal bromination depended on the nature of both the solvent and the in situ electrogenerated reactive brominated species (Br₂ or Br₃⁻) obtained from the oxidation of a bromide salt. It was especially shown that Br₂ reacted more rapidly than Br₃⁻ towards (1). On the other hand, the reactivity of both brominated species appeared to follow the solvent polarity order since the highest reactivity was obtained in DMSO whereas the lowest one was found in DCM.     

POLYMERS WITH PENDENT FUNCTIONAL GROUPS. VI. A COMPARATIVE STUDY ON THE CHLOROMETHYLATION OF LINEAR POLYSTYRENE AND POLYSULFONE WITH PARAFORMALDEHYDE/Me3SiCl

Studies have been carried out on the chloromethylation reaction of polystyrene and polysulfone for obtaining soluble chloromethylated polymers with a high degree of substitution. The mixture of paraformaldehyde/chlorotrimethylsilane as the chloromethylation agent, stannic tetrachloride as the catalyst, and chloroform as the solvent was used for the chloromethylation reaction of these polymers. The degree of substitution and the chlorine content depend on the [SnCl₄]/[polymer structural unit], [Me₃SiCl]/ [polymer structural unit] molar ratios and the reaction time.     

Small‐angle X‐ray scattering analysis of nanophase titanium dioxide,poly[N‐(4‐sulfophenyl)aniline], and their composite

Small‐angle X‐ray scattering and spectroscopic (infrared and ultraviolet–visible) techniques were used to investigate the interactions between titanium dioxide (TiO₂) and the semiconductor polymer poly[N‐(4‐sulfophenyl)aniline] (PSA) in a poly[N‐(4‐sulfophenyl)aniline]/TiO₂ composite (TPSA). The radius of gyration of the cross section, the radius and length of the rodlike particle, the persistence length, the surface fractal dimension, and the PSA layer thickness on TiO₂ in aqueous solutions and in powder form were calculated. The results indicated that the aggregation of TiO₂ particles on drying was reduced by the formation of the composite with the semiconductor polymer. Only the particle length of the TPSA particle (which had a rodlike shape) increased on drying, probably because of increasing void sizes and the formation of aggregation. The persistence length of the TPSA particles decreased with respect to its individual components. The PSA layer thickness on TiO₂ was about 3.6 nm and decreased (to 2.6 nm) on dehydration because of the expulsions of water molecules from the TiO₂/PSA composite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3183–3187, 2003     

Development and Study of Solid Polymer Electrolyte Based on Polyvinyl Alcohol: Mg(ClO4)2

Magnesium ion-conducting solid polymer electrolytes consisting of polyvinyl alcohol with magnesium perchlorate (Mg(ClO₄)₂) as electrolytic salt have been developed and their experimental investigations are reported. The solid polymer electrolytes have been prepared by well-known solution casting method using double-distilled water as a solvent. The highest room temperature conductivity of the order of 10^?4 S cm^?1 was obtained for the solid polymer electrolyte with the composition 80?mol% polyvinyl alcohol:20?mol% Mg(ClO₄)₂. The pattern of the temperature-dependent conductivity shows Arrhenius behavior. The Fourier transform infrared spectroscopy analysis confirms the complex formation of the polymer with the salt. The X-ray diffraction results reveal that the crystalline phase of polymer host has completely changed on the addition of dopant. Differential scanning calorimetry studies show a decrease in melting temperature of the polyvinyl alcohol with the increasing dopant concentration. The real part of dielectric permittivity shows a strong dispersion at lower frequencies, which implies the space charge effects arising from the electrodes. The loss tangent spectrum reveals that the jumping probability per unit time decreases with the increasing salt concentration. The total ionic transference number measured has been found to be in the range of 0.92–0.94 for all the polymer electrolyte systems. The result reveals that the conducting species are predominantly ions. The solid polymer electrolyte with highest conductivity showed an electrochemical stability of 2?V. The results obtained by cyclic voltammetry on stainless steel/solid polymer electrolyte/stainless steel, Mg/solid polymer electrolyte/Mg symmetrical cells show evidence for reversibility.     

Photo-induced crosslinking of water-soluble polymers with a new photobase generator

A strong bicyclic guanidine base, 1,5,7-triaza-bicyclo[4.4.0]dec-5-ene (TBD), is photo-generated from its tetraphenylborate salt (TBD·HBPh₄) and can effectively catalyze the transesterification reaction between the ester and hydroxy groups in polymers. Accordingly, with TBD·HBPh₄ as a photobase generator, a water-soluble polymer blend, namely poly(1-vinylpyrrolidone-co-2-dimethylaminoethyl methacrylate) and 2-hydroxyethyl cellulose, has been developed as a potential eco-friendly photoresist. This photoresist system uses only water as a solvent and as a developer, rather than organic solvents and aqueous alkaline developers. The effects of the amount of photobase generator, polymer composition and photolithographic conditions on the photo-induced crosslinking and patterning of water-soluble polymers were studied.     

Preferential interactions of poly(N-vinyl-2-pyrrolidone) in the binary mixture water/CdCl2

The poly(N-vinyl-2-pyrrolidone)(PVP)(2)/water(1)/CdCl₂(3) ternary system has been studied by viscometry, densimetry and atomic absorption spectrophotometry. In this system a preferential adsorption of Cd²⁺ at all solvent compositions studied and a conformational transition at 4mM of salt, the concentration at which a preferential adsorption minimum of Cd²⁺ in exhibited, are observed. The PVP/Cd²⁺ bound molar ratio is 0·23. CdCl₂ behaves as a salting-in agent for the macromolecule. The binary solvent mixture is thermodynamically more favourable at salt concentrations greater than 10 mM of CdCl₂.     

Water and salt permeability of reinforcement polymer‐gel composite membrane

The charged mosaic polymer membrane (CMM) without reinforcement and the composite charged mosaic polymer membrane (CCMM) with reinforcement were investigated in terms of salt and water transport (permeability). The composite charged mosaic polymer membrane (CCMM) with reinforcement showed a unique transport behavior such as preferential material transport L_p and ω. Water permeability coefficient, L_p and salt permeability coefficient, ω were estimated by taking account of active layer thickness of composite polymer gel. The L_p and ω values of CCMM with reinforcement were larger than those of CMM without reinforcement. On the other hand, the reflection coefficient of CCMM, σ, showed negative value, which suggested preferential material transport to solvent transport. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

LiClO4 salt concentration effect on the properties of PVC‐modified low molecular weight LENR50‐based solid polymer electrolyte

A work was carried out on a solid polymeric electrolyte system comprising blends of poly (vinyl chloride) and liquid 50% epoxidized natural rubber (LENR50) as a polymer host with LiClO₄ as a salt and prepared by solution casting technique. In this paper, the main study was the effect of LiClO₄ salt concentration on the electrolyte properties. The effect of the salt on the electrolyte properties was characterized and analyzed with impedance spectroscopy (EIS), X‐ray diffraction (XRD), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM). The EIS result showed that highest ionic conductivity was obtained at 30 wt % salt with a value of 2.3 × 10^?8 S cm^?1. The XRD results revealed that the LiClO₄ salt was fully complexed within the polymer host as no sharp peaks were observed. However, above 30 wt % of salt, some sharp peaks were observed. This phenomenon was caused by the association of ions. Meanwhile, DSC analysis showed that T_g increased as the salt content increased. This implied that LiClO₄ salt had interaction with polymer host by forming coordination bond. The morphologies' studies showed that good homogeneity and compatibility of the electrolyte were achieved. Upon the addition of the salt, formation of micropores occurred. It was noted that micropores which aid in mobility of ions in the electrolyte system has increased the ionic conductivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Liquid-liquid phase separation in polysulfone/solvent/water systems

The cloud point curves for polysulfone (PSf)/solvent/water systems were determined by a titration method. A small amount of water was needed to induce liquid-liquid demixing and the temperature effect was small. From numerical calculations, it was found that the binary interaction parameters for the PSf/solvent/water system enlarges the homogeneous region in the phase diagram with a smaller nonsolvent-polymer interaction parameter χ₁₃, a greater nonsolvent-solvent interaction parameter χ₁₂, and a smaller solvent-polymer interaction parameter χ₂₃ and the effect of polymer molecular weight was negligible except in the range of low molecular weight. The phase diagrams, calculated with constant χ₁₂ that was chosen from the concentration-dependent interaction parameter g₁₂ value of the concentration range, were similar to the results obtained with g₁₂. The slope of the tie lines indicated that demixing of the ternary system occurred at relatively similar nonsolvent concentration in both phases. A value of 2.7 for the water-PSf interaction parameter was obtained by fitting the experimental cloud point curve with the calculated binodal lines. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2643–2653, 1997     

Behaviour of crosslinked and linear poly[1-(3-sulphopropyl)-2-vinyl-pyridinium-betaine] in aqueous salt solutions

Linear and crosslinked poly[1-(3-sulphopropyl)-2-vinyl-pyridinium-betaine] (PSPV) samples have been prepared by free radical polymerization of the zwitterionic monomer (SPV) in the absence and presence, respectively, of N,N′-methylene-bisacrylamide (MBA). The crosslinked xerogel was swollen to equilibrium at ambient temperature in water and in aqueous solutions of KSCN, KBr and KCl having concentrations ([salt]) extending up to 2 mol dm⁻³. In aqueous salt the degree of swelling exceeded the value in pure water (0.70), the enhancement in swelling being most marked at low values of [salt]. The content of water within hydrogel increased with salt concentration in swelling medium for low values of [salt] but thereafter fell with further increase in [salt]. In contrast, the salt content within swollen hydrogel displayed a continuous increase with increasing [salt]. The partition coefficient expressing concentration of salt in hydrogel relative to that in swelling medium increased sharply with [salt] at low values, but levelled out to values of 0.8–1.2 at higher values of [salt]. The difference in behaviour among the three salts was not dramatic, but indicated that the affinity of salt for the polymer lay generally in the order KSCN>KBr>KCl. This affinity was confirmed by conductometric determinations of the coefficient of selective adsorption of salt to polymer in solutions of linear PSPV. © 1999 Society of Chemical Industry     

Water-soluble copolymers. VI. Dilute solution viscosity studies of random copolymers of acrylamide with sulfonated comonomers

Dilute solution viscosity of a series of random copolymers of acrylamide (AM) with sodium-2-acrylamido-2-methylpropane sulfonate (NaAMPS) and with sodium-2-sulfoethylmethacrylate (NaSEM) has been studied using a four-bulb shear dilution capillary viscometer. The hydrodynamic volume of the copolymers in aqueous media was determined as a function of salt concentration, temperature, shear rate, and time. A linear relationship was observed between the intrinsic viscosity [η]₀ and the reciprocal of the square root of ionic strength in sodium chloride solutions, with salt concentrations varying from 0.043M to 0.257M. Negative temperature coefficients for [η]₀ indicate a decrease in the hydrodynamic volume of the ionic polymer molecules with increasing temperature. The relative zero-shear-intrinsic-viscosity change in distilled water to 0.257M sodium chloride aqueous media is used to elucidate viscosity–structure relationships. A maximum value is reached for this parameter at a composition of about 30 mol % of ionic comonomers for AM–NaAMPS and AM–NaSEM copolymer series.     

New lipophilic cyclo- and poly-phosphazenes containing surfactant substituents

The reaction of the sodium salt of the commercially available surfactant Igepal CA 210^™ with hexachlorocyclotriphosphazene, N₃P₃Cl₆ (1) and poly(dichlorophosphazene), [—P(Cl₂)=N—]_n (Publisher's note: for graphical representation please see printed journal or the Acrobat PDF version on this website.) affords lipophilic cyclo- and poly-phosphazenes SSCP (2) and SSPP (4), respectively. These materials, containing a short chain oligo etheroxy side group while being completely insoluble in water, are soluble in a wide range of solvents ranging from hexane to chloroform. The polymer, SSPP (4) forms polymer–metal salt complexes with lithium salts. DC conductivity measurements by a complex impedance method have been carried out. The maximum conductivity observed for SSPP–LiClO₄ (O: Li ratio, 6:1) is 1·0×10^-6Scm^-1 at 348K. © 1998 SCI.     

Dilute solution viscosity properties of high molar mass poly(acrylonitrile‐co‐itaconic acid)

The intrinsic viscosities [η] and viscosity constants of high molar mass poly(acrylonitrile‐co‐itaconic acid) copolymer in DMF were obtained by the methods of Huggin, Fuoss, Martin and Schulz‐Blaschke. The values of [η] by averaging procedures suggested by Sakai were close to those from Huggins method. There was an abnormal positive deviation from the rectilinearity of the reduced viscosity (η_red) versus concentration (c) plot in all the cases in the dilute regime, which was attributed to the polyelectrolytic effect. This was further confirmed by the analysis by Fuoss method. The deviation from the Huggins dependence is discussed for a good solvent (DMF) alone and in the presence of a non‐solvent, methanol. The deviation cross‐over points c′ and c″ changed with molecular weight, and the concentration range greater than c″ and less than c* was taken for a more reliable determination of intrinsic viscosity. The non‐solvent played a key role in determining the polymer–polymer interactions. The Huggins coefficient increased and the cross‐over points c′ and c″ shifted to higher concentration regime as the mixed solvent became poorer. The inter‐ and intra‐polymer interactions increased in the presence of methanol. In poor solvent, the enhanced intramolecular interactions caused the polymer to shrink in size, causing a reduction in [η] and hydrodynamic volume. Copyright © 2003 Society of Chemical Industry     

Dilute solution properties of cationic poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate)

The dilute solution properties of a cationic polyelectrolyte, poly(dimethyl sulfate quaternized dimethylaminoethyl methacrylate) [poly(DMAEM · C₂H₆SO₄)], are studied by measurements of intrinsic viscosity, degree of binding, and flocculation application. The intrinsic viscosity of this polyelectrolyte is related to the type and concentration of added salt. The intrinsic viscosity behavior for cationic polyelectrolyte resulting from the electrostatic repulsive force of the polymer chain is contrasted with polyampholyte. The polyelectrolyte in the presence of KCl has a lower degree of binding, indicating that the proton ion (H⁺) is relatively difficult to bind to the CH₃SO₄^? at the polymer end. The polymerization of DMAEM · C₂H₆SO₄ in 0.5M KCl aqueous solution proceeded more easily than that of DMAEM · C₂H₆SO₄ in pure water. The polymerization rate of DMAEM · C₂H₆SO₄ is found to pass through an extreme value as a function of pH. Optimum flocculation, corresponding to the complete removal of turbidity in the supernatant, is achieved. Beyond the optimum flocculation, high polymer dosages redisperse the bentonite suspensions.     

Preparation and characterization of chloromethylated/quaternized poly(phthalazinone ether sulfone ketone) for positively charged nanofiltration membranes

Chloromethylated poly(phthalazinone ether sulfone ketone) (CMPPESK) as a novel membrane material was successfully prepared from poly(phthalazinone ether sulfone ketone), with concentrated sulfuric acid as the solvent and catalyst, and chloromethyl octyl ether with lower toxicity as the chloromethylated regent. The effects of the reaction conditions on the preparation of CMPPESKs with different degrees of chloromethylation were examined. The quantity of chloromethyl groups per repeated unit (DCM) of CMPPESK was determined by the method of analysis of the chlorine element, and structures were characterized by ¹H‐NMR spectroscopy. The introduction of chloromethyl groups into the polymer chains led to a decrease in the decomposition temperature. With increasing DCM, the initial degradation temperature declined. CMPPESK had good solubility and was soluble in N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), and chloroform. However, quaternized poly(phthalazinone ether sulfone ketone) (QAPPESK) had excellent solvent resistance, was only partly soluble in sulfuric acid (98%), and was swollen in N,N‐dimethylformamide. QAPPESK nanofiltration (NF) membranes had about 90% rejection for MgCl₂, and the performance of the NF membrane prepared with DMAc as the solvent was superior to that of the NF membrane prepared with NMP as the solvent. In addition, the rejection to the different salt solutions followed the following sequence: MgCl₂ > MgSO₄ > NaCl > Na₂SO₄. Furthermore, the thermotolerance of the QAPPESK NF membrane was examined, and the results show that when the solution temperature rose from 11 to 90°C, the water flux increased more than threefold with stable salt rejection. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008