Propylene sorption and coordinative interactions for poly(N‐vinyl pyrrolidone‐co‐vinyl acetate)/silver salt complex membranes

When poly(N‐vinyl pyrrolidone‐co‐vinyl acetate) (PVP‐co‐PVAc) containing amide and ester groups were complexed with silver salts to form silver polymer electrolyte membranes, their separation performance of propylene/propane mixtures showed the high selectivity of propylene over propane of 55 and the high mixed gas permeance of 12 GPU (1 GPU = 1.0 × 10^?6 cm³(STP) cm^?2 s^?1 cmHg^?1). The separation performance strongly depends on the composition of the copolymer: the higher concentration of PVP in the copolymer, the better separation performance was achieved. These results suggest that the amide group is more effective in facilitated propylene transport than the ester group, primarily due to the stronger interaction of the silver ions with the amide than the ester oxygens, as demonstrated by FT‐IR and FT‐Raman spectroscopies. In‐situ FT‐IR spectra upon propylene sorption also demonstrate that the interaction strength of the silver ions with the ligands is arranged: amide > C?C > ester. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2263–2269, 2007     

Complexation of Silver Ions with Poly(butyl methacrylate) and Propylene Toward Facilitated Propylene Transport

Silver salts are dissolved in poly(butyl methacrylate) to derive polymer electrolytes via coordinative interaction between the silver ion and the carbonyl oxygen atom. The dissolved silver ions react subsequently with propylene to form reversible silver/olefin complexes that can be utilized as olefin carriers for facilitated olefin transport. The complexation behavior and its effects on propylene transport were investigated by means of Raman and FT‐IR spectroscopy, as well as dielectric thermal analysis.     

Effect of the polymer matrix on the formation of silver nanoparticles in polymer–silver salt complex membranes

When polymer–silver salt complex membranes were exposed to UV irradiation, the separation performances of both the permeance and selectivity for propylene–propane decreased, which was primarily attributed to the reduction of the silver ions in the membranes to silver nanoparticles. Here, the effect of the polymer matrix on the formation of silver nanoparticles in the polymer–silver salt complex membranes was investigated. This effect was assessed for the complexes of two kinds of silver salts (AgBF₄ and AgCF₃SO₃) with several polymeric ligands containing three different carbonyl groups, including poly(vinyl pyrrolidone) (PVP) with an amide group, poly(vinyl methyl ketone) (PVMK) with a ketone group, and poly(methyl methacrylate) (PMMA) with an ester group. UV–vis spectra and transmission electron microscopy (TEM) images clearly indicated that the reduction rate of the silver ions has the following order in the various polymer matrices: PVP > PVMK > PMMA, whereas the size and the distribution of the nanoparticles exhibited the reverse order. The tendency to form silver nanoparticles was explained in terms of the differences between the comparative strengths of the interactions of the silver ions with the different carbonyl oxygens in the matrices, as well as that of the silver ions with counteranions, which was characterized by X‐ray photoelectron spectroscopy (XPS) and FT‐Raman spectroscopy. It was concluded that when the concentration of free silver ions was low due to weak polymer–silver ion and strong silver ion–anion interactions, as found with PMMA, the reduction rate of silver ions to silver nanoparticles was slow. Therefore, the PMMA–silver complex membranes were less sensitive to decreases in separation performance upon UV irradiation than compared to the PVP membranes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1168–1178, 2006     

Modelling of the Phase Separation Behaviour of Semiflexible Diblock Copolymers

Silver salts are dissolved in poly(butyl methacrylate) to derive polymer electrolytes via coordinative interaction between the silver ion and the carbonyl oxygen atom. The dissolved silver ions react subsequently with propylene to form reversible silver/olefin complexes that can be utilized as olefin carriers for facilitated olefin transport. The complexation behavior and its effects on propylene transport were investigated by means of Raman and FT‐IR spectroscopy, as well as dielectric thermal analysis.     

Complexation mechanism of olefin with silver ions dissolved in a polymer matrix and its effect on facilitated olefin transport

Remarkable separation performance of olefin/paraffin mixtures was previously reported by facilitated olefin transport through silver-based polymer electrolyte membranes. The mechanism of facilitated olefin transport in solid membranes of AgCF3SO3 dissolved in poly(N-vinyl pyrrolidone) (PVP) is investigated. In silver polymer electrolyte membranes, only free anions are present up to the 2:1 mole ratio of [C=O]:[Ag], and ion pairs start to form at a ratio of 1:1, followed by higher-order ionic aggregates above a ratio of 1:2. At silver concentrations above 3:1, the propylene permeance increases almost linearly with the total silver concentration, unexpectedly, regardless of the silver ionic constituents. It was also found that all the silver constituents, including ion pairs and higher order ionic aggregates, were completely redissolved into free anions under the propylene environment; this suggests that propylene can be a good ligand for the silver cation. From these experimental findings, a new mechanism for the complexation reaction between propylenes and silver salts in silver-polymer electrolytes was proposed. The new mechanism is consistent with the linearity between the propylene permeance and the total silver concentration regardless of the kind of the silver constituents. Therefore, the facilitated propylene transport through silver-polymer electrolytes may be associated mainly with the silver cation weakly coordinated with both carbonyl oxygen atoms and propylene.     

Structure and separation properties of π‐complex membranes comprising poly(hexamethylenevinylene) and silver tetrafluoroborate

Polymer/silver‐ion π‐complex membranes consisting of poly(hexamethylenevinylene) (PHMV) and silver tetrafluoroborate exhibit unusually high separation performance for olefin/olefin and olefin/paraffin mixtures. The formation of π complexes between silver ions and unsaturated C?C bonds of PHMV has been confirmed with wide‐angle X‐ray scattering, differential scanning calorimetry, and X‐ray photoelectron spectroscopy. Fourier transform infrared and ultraviolet spectroscopy studies have revealed that silver ions make π complexes with olefins such as 1,3‐butadiene, propylene, and ethylene. Of these three olefins, 1,3‐butadiene has the highest binding affinity with silver ions in dissolved in PHMV, and this results in its higher solubility and permeance. Therefore, the π‐complex membranes exhibit unusually high separation performance for olefin/olefin and olefin/paraffin mixtures. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1434–1441, 2006     

Role of anions for the reduction behavior of silver ions in polymer/silver salt complex membranes

The reduction of silver ions to silver nanoparticles is an essential issue in polymer/silver salt complex membranes for facilitated olefin transport, because it has a critical influence on the long-term stability of membrane performance. In this study, the role of anions for the formation of silver nanoparticles in polymer/silver salt complexes was investigated. This role was assessed for the complexes of poly(N-vinyl pyrrolidone) (PVP) with three silver salts including AgBF₄, AgCF₃SO₃, and AgNO₃. Especially, UV irradiation to the membranes was used to clearly investigate the reduction behavior of silver ions. Separation performance test, UV–vis spectroscopy and transmission electron microscopy (TEM) clearly show that the reduction rate of silver ions strongly depends on the counteranions of salt, and has the following order: AgBF₄ > AgCF₃SO₃ > AgNO₃. This behavior of the formation of silver nanoparticles in polymer/silver salt complex membranes is explained in terms of the interaction strength of silver ions with the carbonyl oxygens of polymer, and that of silver ions with counteranions. It is concluded that when the former interaction is strong and the latter one is weak, the reduction rate of silver ions to silver nanoparticles is fast, and vice versa. These interactions were characterized using FT-IR, FT-Raman spectroscopy, and theoretical ab initio calculation.     

Specific interactions and phase behavior of ternary poly(2‐vinylpyridine)/poly(N‐vinyl‐2‐pyrrolidone)/bisphenol A blends

Hydrogen‐bonding interactions between bisphenol A (BPA) and two proton‐accepting polymers, poly(2‐vinylpyridine) (P2VPy) and poly(N‐vinyl‐2‐pyrrolidone) (PVP), were examined by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The Flory–Huggins interaction‐energy densities of BPA/P2VPy and BPA/PVP blends were determined by the melting point depression method. The interaction parameters for both BPA/P2VPy and BPA/PVP blend systems were negative, demonstrating the miscibility of BPA with P2VPy as well as PVP. The miscibility of ternary BPA/P2VPy/PVP blends was examined by DSC, optical observation, and solid‐state nuclear magnetic resonance spectroscopy. The experimental phase behavior of the ternary blend system agreed with the spinodal phase‐separation boundary calculated using the determined interaction‐energy densities. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1125–1134, 2002     

Silver nanoparticles stabilized by crosslinked poly(vinyl pyrrolidone) and its application for facilitated olefin transport

Positively polarized silver nanoparticles by poly(vinyl pyrrolidone) (PVP) have been demonstrated for use as stable olefin carriers for facilitated olefin transport membranes. The formation and size of silver nanoparticles stabilized by PVP were monitored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Nanocomposite membranes consisting of polymer and silver nanoparticles stabilized by PVP exhibited the high separation performance for olefin/paraffin mixtures. X-ray photoelectron spectroscopy (XPS) showed that silver nanoparticles stabilized by PVP exhibited a high positive polarity, resulting in the reversible interaction between the surface of silver nanoparticles and olefin molecules.     

Polymer electrolyte membranes by in situ polymerization of poly(ethylene carbonate‐co‐ethylene oxide) macromonomers in blends with poly(vinylidene fluoride‐co‐hexafluoropropylene)

Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10^?6 S cm^?1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (T_g) of the ion conductive phase by ～5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10^?6 S cm^?1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the T_g of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007     

Complexation of phthalate oxygens in poly(ethylene phthalate) with silver ions and its effect on the formation of silver nanoparticles

The interaction of a phthalate group in poly(ethylene phthalate) (PEP) with silver ion has been elaborated in detail to understand the reduction behavior of silver ions to silver nanoparticles. Previously, the polymer electrolytes consisting of silver ions dissolved in PEP have shown highly stable separation performance for propylene/propane mixtures primarily due to the retardation of the reduction reaction of silver ions to silver nanoparticles, which is possible by means of the chelating bonds between phthalate groups and silver ions. Thus, in this study, the interaction was systematically investigated by both the theoretical ab initio calculation and the experimental Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The results show that the interaction of silver ion with phthalate group in PEP is approximately two times stronger than that with other functional groups such as amide, ketone, and ester in various polymers, in which the latter ones show the rapid reduction reaction and consequently lose their olefin carrier activity with time. Therefore, it is concluded that the reduction reaction of silver ions to silver nanoparticles is retarded remarkably in PEP/silver salts systems primarily because of the strong interaction between the phthalate group in PEP and silver ion, and consequently the formation of silver nanoparticles would be effectively prohibited, as confirmed by transmission electron microscopy and ultraviolet–visible spectroscopy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3344–3350, 2004     

Proton‐conducting poly(vinylpyrrolidon)–polyphosphoric acid blends

Anhydrous, proton‐conducting polymer electrolytes of poly(vinylpyrrolidon) (PVP) with polyphosphoric acid (PPA) were prepared. PVP‐x‐PPA blends were obtained for 0.5 ≤ x ≤ 3, where x was the number of moles of PO per polymer repeat unit. Fourier transform infrared studies indicated protonation of the carbonyl group in the five‐member ring. Thermogravimetric analysis showed that these materials were stable up to about 180 °C. Differential scanning calorimetry data demonstrated that the addition of the acid plasticized the material, shifting the glass‐transition temperature from 180 °C for the pure polymer to ?23 °C for x = 3. The temperature dependence of the mechanical properties was investigated with shear experiments. The direct‐current conductivity increased with x and reached about 10^?5 S/cm at ambient temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1987–1994, 2001     

Simultaneous synthesis of silver nanoparticles and poly(2,5‐dimethoxyaniline) in poly(styrene sulfonic acid)

Silver nanoparticles were formed in situ along with poly(2,5‐dimethoxyaniline) (PDMA) in an interconnected network matrix (reactor), comprising the electronic conductive polymer, PDMA, and a polyelectrolyte, poly(styrene sulfonic acid) (PSS), through the simultaneous reduction of Ag⁺ ions and polymerization of 2,5‐dimethoxyaniline. In situ ultraviolet‐visible spectroscopy showed that peaks corresponding to the plasmon resonance of silver nanoparticles at 411 nm and the polaronic transition of PDMA at 438 nm provided evidences for the simultaneous formation of silver nanoparticles and PDMA. Transmission electron microscopy and size distribution analysis revealed the presence of spherical silver nanoparticles with an average diameter of 12 nm in the composite. X‐ray photoelectron spectroscopy showed that the amine units in PDMA changed to imine units upon the formation of silver nanoparticles. A comprehensive mechanism for the formation of the PDMA‐PSS‐Ag nanocomposite is proposed. A 10‐fold increase in the conductivity was noticed for the PDMA–PSS–Ag nanocomposite (1 S/cm) in comparison with the PDMA–PSS composite (0.1 S/cm). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3843–3852, 2006     

Interactions between metal chlorides and poly(vinyl pyrrolidone) in concentrated solutionsand solid‐state films

The rheological behavior of poly(vinyl pyrrolidone) (PVP)/N,N‐dimethylformamide (DMF) solutions containing metal chlorides (LiCl, CaCl₂, and CoCl₂) were investigated, and the results showed that the nature of the metal ions and their concentration had an obvious effect on the steady‐state rheological behavior of PVP–DMF solutions with different molecular weights. The apparent viscosity of the PVP–DMF solutions increased with an increasing metal‐ion concentration, and the viscosity increment was dependent on the metal‐ion variety_. For a CaCl₂‐containing PVP–DMF solution, for example, the critical shear rate at the onset of shear thinning became smaller with increasing CaCl₂ concentration. It was believed that multiple interactions among metal ions, carbonyl groups of PVP, and amide groups in DMF determined the solution properties of these complex fluids; therefore, ¹³C NMR spectroscopy was used to detect the interactions in systems of PVP–CaCl₂–DMF and PVP–LiCl–DMF solutions. NMR data showed that there were obvious interactions between the metal ions and the carbonyl groups of the PVP segments in the DMF solutions. Furthermore, IR spectra of the PVP/metal chloride composites demonstrated that the interaction between the metal ions and carbonyl groups in the PVP unit occurred and that the PVP chain underwent conformational variations with the metal‐ion concentration. DSC results indicated that the glass transition temperatures of the PVP/metal chloride composites increased with the addition of metal ions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1589–1598, 2007     

Ionic interaction behavior and facilitated olefin transport in poly(n‐vinyl pyrrolidone):Silver triflate electrolytes; Effect of molecular weight

Interactions of cation/anion and cation/polymer in poly(N‐vinyl pyrrolidone) (PVP):silver triflate (AgCF₃SO₃) electrolytes with different weight‐average molecular weights (M_w's) of 1 × 10⁶ (1 M), 3.6 × 10⁵ (360 K), 4 × 10⁴ (40 K), and 1 × 10⁴ (10 K) have been studied with IR and Raman spectroscopies. According to the change of the C?O peak, coordination of silver ions by C?O in a low M_w (10 or 40 K) PVP matrix tend to be always thermodynamically favorable than high M_w (1 M or 360 K) PVP, demonstrating that the polymer matrix of low M_w dissolves silver salts more effectively. In addition, silver cations interact with both larger SO and smaller CF₃ to form ion pairs, and the former interaction is stronger than the latter in a monomer or low M_w polymer matrix (40 K, 10 K), as demonstrated by theoretical ab initio calculation or experimental spectroscopy, respectively. However, CF₃ interacts more favorably with silver cation than SO in high M_w (1 M and 360 K) PVP, which is ascribed to the steric effect of the bulky SO anion by highly entangled polymer chains. Despite the superior dissolving property of the low M_w polymer matrix, the membranes consisting of low M_w PVP and AgCF₃SO₃ exhibited poor separation performance for propylene/propane mixtures in comparison with those of high M_w, presumably because of the poor mechanical property for membrane formation in low M_w PVP. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1813–1820, 2002     

Syntheses and characterizations of poly[2‐(dimethylamino)ethyl methacrylate]–poly(propylene oxide)–poly[2‐(dimethylamino)ethyl methacrylate] ABA triblock copolymers

A novel, near‐monodisperse, well‐defined ABA triblock copolymer, poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(propylene oxide)‐b‐poly[2‐(dimethylamino)ethyl methacrylate], was synthesized via oxyanion‐initiated polymerization. The initiator was a telechelic‐type potassium alcoholate prepared from poly(propylene glycol) and KH in dry tetrahydrofuran. The copolymers produced were characterized by Fourier transform infrared, ¹H NMR, and gel permeation chromatography (GPC). GPC and ¹H NMR analyses showed that the products obtained were the desired copolymers, with narrow molecular weight distributions (ca. 1.09–1.11) very close to that of the original poly(propylene glycol). ¹H NMR, surface tension measurements, and dynamic light scattering all indicated that the triblock copolymer led to interesting aqueous solution behaviors, including temperature‐induced micellization and very high surface activity. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 624–631, 2002; DOI 10.1002/pola.10144     

Enhanced mobility and environmental stability in all organic field‐effect transistors: The role of high dipole moment solvent

Low‐operating voltage, high mobility, and stable organic field‐effect transistors (OFETs) using polymeric dielectrics such as pristine poly(4‐vinyl phenol) (PVP) and poly(methyl methacrylate) (PMMA), dissolved in solvents of high dipole moment, have been achieved. High dipole moment solvents such as propylene carbonate and dimethyl sulfoxide used for dissolving the polymer dielectric enhance the charge carrier mobilities by three orders of magnitude in pentacene OFETs compared with low dipole moment solvents. Fast switching circuits with patterned gate PVP‐based pentacene OFETs demonstrated a switching frequency of 75 kHz at input voltages of |5 V|. The frequency response of the OFETs is attributed to a high degree of dipolar‐order in dielectric films obtained from high‐polarity solvents and the resulting energetically ordered landscape for transport. Remarkably, these pentacene‐based OFETs exhibited high stability under bias stress and in air with negligible shifts in the threshold voltage. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1533–1542     

Self‐healing of poly(propylene oxide)‐polybenzoxazine thermosets by photoinduced coumarine dimerization

In this work, a self‐healing strategy for poly(propylene oxide)s bearing coumarine‐benzoxazine units (PPO‐CouBenz)s based on light induced coumarine dimerization reactions is described. Four different types of poly(propylene oxide) amines with molecular weights ranging from 440 to 5000 Da were reacted with formaldehyde and 4‐methyl‐7‐hydroxycoumarin to yield desired (PPO‐CouBenz)s. The crosslinked polymer films were prepared by solvent casting of various compositions of PPO‐CouBenzs in chloroform followed by thermal ring opening reaction of benzoxazine groups at 210–240 °C. Thermal curing and thermal stability of the initial PPOs and final products were investigated. Using allyl benzoxazine in the formulation, it was demonstrated that the toughness of the films was improved. Photoinduced healing of coumarin‐based cured PPO‐CouBenz polymer films was investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2911–2918     

One‐step synthesis of poly(lactic‐co‐glycolic acid)‐g‐poly‐1‐vinylpyrrolidin‐2‐one copolymers

The radical polymerization of 1‐vinylpyrrolidin‐2‐one (NVP) in poly(lactic‐co‐glycolic acid) (PLGA) 50:50 at 100 °C leads to amphiphilic PLGA‐g‐PVP copolymers. Their composition is determined by FT‐IR spectroscopy. Thermogravimetric analyses agree with FT‐IR determinations. Saponification of the PLGA‐g‐PVP polyester portion allows isolating the PVP side chains and measuring their molecular weight, from which the average chain transfer constant (C_T) of the PLGA units is estimated. The MALDI‐TOF spectra of PVP reveal the presence at one chain end of residues of either glycolic acid‐ or lactic acid‐ or lactic/glycolic acid dimers, trimers and one tetramer, the other terminal being hydrogen. This unequivocally demonstrates that grafting occurred. Accordingly, the orthogonal solvent pair ethyl acetate—methanol, while separating the components of PLGA/PVP intimate mixtures, fails to separate pure PVP or PLGA from the reaction products. All PLGA‐g‐PVP and PLGA/PLGA‐g‐PVP blends, but not PLGA/PVP blends, give long‐time stable dispersions in water. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1919–1928     

Synthesis and in vitro degradation of poly(N‐vinyl‐2‐pyrrolidone)‐based graft copolymers for biomedical applications

This work is devoted to the design of a novel family of hydrosoluble biomaterials: poly(N‐vinyl‐2‐pyrrolidone) (PVP)‐based graft copolymers. A synthesis route has been elaborated in which ω‐functionalized PVP is prepared via chain‐transfer radical polymerization, end‐group modified, and subsequently grafted onto a polyhydroxylated backbone, typically dextran or poly(vinyl alcohol). The resulting graft copolymer biomaterials are designed for use in various biomedical applications, particularly as materials with a stronger potential for plasma expansion than already existing products have. The graft copolymers are potentially degradable because the PVP grafts are connected to the polyol backbone via a hydrolytically labile carbonate or ester linkage. The degradation of the graft copolymers was performed in vitro over a period of 6 weeks. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3652–3661, 2002