Water-soluble complexes of star-shaped poly(acrylic acid) with quaternized poly(4-vinylpyridine)

The interaction of star-shaped poly(acrylic acid) having various numbers of arms (5, 8, and 21) and a strong cationic polyelectrolyte, viz., poly( N-ethyl-4-vinylpyridinium bromide), was examined at pH 7 by means of turbidimetry and dynamic light scattering. Mixing aqueous solutions of the oppositely charged polymeric components was found to result in phase separation only if their base-molar ratio Z = [N+]/[COO (-) + COOH] exceeds a certain critical value ZM ( ZM < 1); this threshold value is determined by the number of arms of the star-shaped polyelectrolyte and the ionic strength of the surrounding solution. At Z < ZM, the homogeneous aqueous mixtures of the oppositely charged polymeric components contain two types of complex species clearly differing in their sizes, with the fractions of these species appearing to depend distinctly on the number of arms of the star-shaped poly(acrylic acid), the base-molar ratio of the oppositely charged polymeric components in their mixtures, and the ionic strength of the surrounding solution. The small complex species (major fraction) are assumed to represent the particles of the water-soluble interpolyelectrolyte complex whereas the large complex species (minor fraction) are considered to be complex aggregates.     

Chromium retention properties of N-alkyl quaternized poly(4-vinylpyridine)

The ability of solid N-alkyl quaternized poly(4-vinylpyridine) with hexyl, octyl and decyl bromide for the retention of chromate and dichromate forms of Cr(VI) in aqueous solutions is studied. The retention of Cr(VI) was investigated by batch equilibrium procedure and this study was supported by UV-vis spectrophotometry, infrared (IR) spectroscopy and thermal analysis (glass transition temperature and thermal degradation). The retention of Cr(VI) was possible in the range of concentrations between 1 × 10⁻⁶ and 1 × 10⁻³ mol/L and it was dependent on the length of the polyelectrolyte side aliphatic chain. Thermogravimetric analysis (TGA) indicated that solid phase, (N-alkyl quaternized poly(4-vinylpyridine), with Cr(VI) (P4VPyC8-Cr(VI)) is slightly more stable than P4VPyC8 in absence of Cr(VI). Differential scanning calorimetric (DSC) measurements indicate that the segmental movements are restricted due to the presence of chromate and/or dichromate ions in the solid phase.     

Association of quaternized poly(4-vinylpyridine) and sodium dodecyl sulfate in water-alcohol solvents

Complexation of a cationic polyelectrolyte (partially quaternized poly(4-vinylpyridine)) and the anionic surfactant sodium dodecyl sulfate in aqueous-organic solutions with different ratios of the components is studied by ion-selective potentiometry, viscometry, spectrophotometry, and microelectrophoresis. Effects of the nature and composition of water-alcohol (methanol, ethanol, and isopropanol) mixtures on the parameters of binding of surfactant ions by polyelectrolytes, the hydrodynamic properties of complexes, and the phase state of the system are examined. The addition of small amounts of ethanol and isopropanol to water (20 vol % ethanol and 10 vol % isopropanol) leads to an increase in the intensity of sodium dodecyl sulfate binding by the polyelectrolyte. The addition of up to 30 vol % methanol is not accompanied by a change in the character of surfactant binding relative to that of the aqueous solution. The relationship between the complexing behavior of the polyelectrolyte and the structural features of mixed solvents is discussed.     

Single-ion and salt conductor polymer electrolytes based on poly(4-vinylpyridine) quaternized with poly(ethylene oxide) side chains

A new type of single-ion conductor with fixed cation was synthesized by spontaneous anionic polymerization of 4-vinylpyridine in the presence of short polyethylene oxide ( PEO ) chains as alkylating agents. These comblike polymers have low T_gs and are amorphous with the shorter PEO s. Their conductivities are unaffected by the nature of the anion ( Br ⁻, ClO ₄⁻, and tosylate) and are controlled by the free volume and the mobility of the pendant cation. By comparison of the results at constant free volume, it is shown that the charge density decreases with the increasing length of pendant PEO demonstrating that PEO acts only as a plasticizing agent. Best conductivity results (σ = 10⁻⁵ S cm⁻¹ at 60°C) are obtained with PEO side chains of molecular weight 350. With this sample, the conductivity in the presence of various amounts of added salt (LiTFSI) was studied. A best value of 10⁻⁴ S cm⁻¹ at 60°C is obtained with a molar ratio EO/Li of 10. It is shown that, over the range of examined concentrations (0.2–1.3 mol Li kg⁻¹), the reduced conductivity σ_r/c increases linearly with increasing salt concentration showing that the ion mobility increases continuously. Such behavior is quite unusual since in this concentration range a maximum is generally observed with PEO systems. To interpret this result and by analogy with the behavior of this type of polymer in solution, it is proposed that the conformation of these polymers in the solid state is segregated with the P4VP skeleton more or less confined inside the dense coils surrounded by the PEO side chains. Under the influence of the increasing salt concentration, this microphase separation vanishes progressively: The LiTFSI salt exchanges with the tosylate anions and acts as a miscibility improver agent. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2719–2728, 1997     

Miscibility of poly(butyl methacrylate-CO-methacrylic acid) or poly(styrene-CO-methacrylic acid) with poly(styrene-CO-4-vinylpyridine) or poly(butyl methacrylate-CO-4-vinylpyridine)

The miscibility of blends of copolymers of different compositions of butyl methacrylate-co-methacrylic acid or styrene-co-methacrylic acid with styrene-co-4-vinylpyridine or butyl methacrylate-co-4-vinylpyridine was studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. It was found that these blends were miscible in part as a result of specific favorable interactions between the carboxylic acid and pyridine groups within the polymer chains. Evidence of such interactions was obtained from the single composition-dependent glass transition temperature and the FTIR results.     

Stereoregularity of poly(2-vinylpyridine) and poly-(4-vinylpyridine)

In order to determine the stereoregularity of poly(4-vinylpyridine), 4-vinylpyridine-β,β-d₂ was synthesized from 4-acetylpyridine. The ¹H-NMR spectra of the deuterated and nondeuterated polymers were measured and analyzed. From the ¹H-NMR spectra of poly(4-vinylpyridine-β,β-d₂), triad tacticity can be obtained, while the ¹H-NMR spectra of nondeuterated poly(4-vinylpyridine) give the fraction of isotactic triad. The ¹³C-NMR spectra of poly(4-vinylpyridine) were also observed, and the spectra of C₄ carbon of polymers were assigned by the pentad tacticities. The fraction of isotactic triad of poly(2-vinylpyridine) and poly(4-vinylpyridine) obtained under various polymerization conditions were determined. The radical polymerization and anionic polymerizations with phenylmagnesium bromide and n-butyllithium as catalysts of 4-vinylpyridine gave atactic polymers.     

Hydrogen-bonding-directed layer-by-layer assembly of poly(4-vinylpyridine) and poly(4-vinylphenol): effect of solvent composition on multilayer buildup

This paper describes the buildup of hydrogen-bonding-directed poly(4-vinylpyridine)/poly(4-vinylphenol) (PVPy/PVPh) multilayer film that was fabricated by layer-by-layer (LbL) assembly of PVPy and PVPh from an ethanol solution. UV-visible spectroscopy and Fourier transform infrared (FT-IR) spectroscopy revealed a uniform deposition process. The interaction between PVPy and PVPh was identified as hydrogen bonding through FT-IR spectroscopy and temperature-dependent IR spectral changes of the hydrogen-bonded multilayer. Notably, we discussed the effect of solvent conditions on the growth of PVPy/PVPh multilayer films monitored by UV-visible spectroscopy. It was found that increasing the ratio of N,N-dimethylformamide (DMF) in the mixed ethanol/DMF solvents resulted in a marked decrease of the amount of polymers adsorbed, which was attributed to the increased polarity of the adsorption solutions. Furthermore, the solvent stability of PVPy/PVPh multilayer film in mixed ethanol/DMF solvents with different DMF ratios was also investigated. As a result, a new method for tuning the structure of hydrogen-bonding-directed multilayer film was developed.     

Association of copolymers of methacrylic acid and 4-vinylpyridine in comparison with an intermacromolecular complex of poly(methacrylic acid) with poly(4-vinylpyridine)

Solution properties of copolymers [C(MA-Py)x] of methacrylic acid and 4-vinylpyridine and intermacromolecular complexes of poly(methacrylic acid) (PMAA) and poly(4-vinylpyridine) (PVP) in the presence or absence of a proton-accepting water-soluble polymer such as poly(ethylene glycol) (PEG) in water/methanol mixed solvent are studied by potentiometric titration, turbidity and viscosity methods. These copolymers behave like polyampholytes and their solubilities are strongly dependent with pH changes. The pH regions where they are precipitated around their isoelectric points are narrower than those of the intermacromolecular complex of PMAA with PVP. The polyampholyte can form an intermacromolecular complex with PEG in acidic solution but this complex is soluble in the medium.     

Kinetics and steric limitation of quaternization of poly(4-vinylpyridine) with mesogenic ω-(4′-methoxy-4-biphenylyloxy)alkyl bromides

The kinetics and characteristics of the quaternization of poly(4-vinylpyridine) with very large alkylating agents are studied with the main aim to demonstrate the occurrence of a limitation of the reaction due to steric effect. Kinetics are carried out in sulfolane at different temperatures with two ω-(4'-methoxy-4-biphenylyloxy)alkyl bromides. An important limitation of the reaction is demonstrated: 30% of the pyridine groups are inaccessible at 333 K, 23% at 355.5 K, and 4% at 363 K. Post-quaternization experiments with butyl bromide of already partially quaternized P4VP also demonstrate this limitation. The occurrence of global steric hindrance and hydrophobic effects affecting the conformation of the chain in solution is proposed to explain the limited accessibility of the pyridine groups. The results question the classical neighboring group model generally used to describe the slowing down of the quaternization reaction with increasing quaternization ratio. The thermal stability of the quaternized polymers and the colors of the reaction medium are also discussed. © 1992 John Wiley & Sons, Inc.     

Thermal degradation and stability of poly(4-vinylpyridine) homopolymer and copolymers of 4-vinylpyridine with methyl acrylate

The thermal stability and degradation behaviour of poly(4-vinylpyridine) (PVP) homopolymer and copolymers of 4-vinylpyridine and methyl acrylate (VP-MA) have been investigated. The reactivity ratios in the copolymerization were determined using an NMR method. The apparent activation energies of the degradation of the homopolymers and copolymers were calculated using the Arrhenius equation.     

Complexation of sequence-ordered methacrylic acid copolymers with poly(4-vinylpyridine)

The complexation of three kinds of sequence-ordered acid (co)polymers with a base homopolymer was studied. The acid polymers used are poly(methacrylic acid) 1 , alternating (1:1) ethylene-methacrylic acid copolymer 2 , and periodic (2:1) ethylene-methacrylic acid copolymer 3 , and the base polymer is poly(4-vinylpyridine) 4. When mixing a methanol solution of 1, 2 , or 3 with that of 4 (0.1 M of each functional group), precipitate was formed immediately for all polymer pairs. All the precipitates contained carboxyl and pyridyl groups in ca. 1:1 molar ratio and showed IR spectra indicating the hydrogen bonding between carboxyl and pyridyl groups. When mixing dilute methanol solutions (10⁻⁴M) of the above polymer pairs, no precipitation was observed, but the extinction coefficient (ϵ_B) at 255 nm of pyridyl groups in 4 was found to increase with an increasing acid polymer concentration. This is ascribed to hydrogen bonding between carboxyl and pyridyl groups in methanol. Based on the ϵ_B variation, the order of complexation constants for acid/base polymer pairs was estimated as follows: 1/4 pair ∼ 2/4 pair ≫ 3/4 pair. © 1996 John Wiley & Sons, Inc.     

Self-assembly of pH-sensitive random copolymers: poly(styrene-co-4-vinylpyridine)

A series of pH-sensitive random copolymers, poly(styrene-co-4-vinylpyridine) (PSVP), with molecular weight about 10,000 and 4-vinylpyridine molar contents of 19-53%, were conveniently synthesized by free radical polymerization. The copolymers experience the formation, swell, and dissociation of multichain nanoparticles when the pH of the aqueous solutions/dispersions changes from 5.1 to 1.0. The nanoparticles have hydrodynamic diameters around 100 nm, a spherical shape, and a relatively uniform structure in a pH range of about 5-3 and a multicore structure at lower pH. The random distribution of the building units causes some of the hydrophilic units, protonated 4-vinylpyridine groups, to be trapped inside the nanoparticles. So the hydrophobicity of the nanoparticles is tunable by changing the 4-vinylpyridine content in the copolymers. For the copolymers with higher 4-vinylpyridine molar content, the pH range in which the multichain nanoparticles form shifts to higher values, the multichain nanoparticles dissociate, and the copolymers form single-chain hydrophobic domains at low pH.     

Crosslinked and quaternized poly(4-vinylpyridine)/polypyrrole composite as a potential candidate for the detection of low humidity

Poly(4-vinylpyridine) was crosslinked and quaternized with 1,4-bromobutane to form a polyelectrolyte humidity sensitive film on an interdigitated gold electrode, which was further coated with a layer of polypyrrole by a facile method of vapor phase polymerization. The composite so prepared was characterized by UV-vis spectroscopy and scanning electron microscopy. The investigations on the humidity sensitive properties of the composite revealed that it exhibited an impedance as low as 10(5) Omega even at 0%RH due to the existence of intrinsic conducting polypyrrole, thus conquering the difficulties in measuring low humidity with resistive-type humidity sensors. The impedance of the composite changed linearly with humidity in the range of 0-60%RH with good sensitivity. In addition, its response time (t(90%)) for adsorption and desorption between 33% and 97%RH was estimated to be 33 s and 110 s, respectively, and a hysteresis of 5%RH was observed. All these suggest it is promising as a sensitive material for low humidity detection. The effect of concentration and ratio of oxidizing agent to doping agent, polymerization temperature of pyrrole on the humidity sensitive properties of the composite have been investigated. A sensitive mechanism of the composite was proposed by taking into account the contribution of both the intrinsic electronic conduction and ionic conduction.     

Kinetics and mechanism of the quaternization of poly(4-vinyl pyridine) with 1-bromopropane

The kinetics of the quaternization of poly(4-vinyl pyridine) with 1-bromopropane in sulfolane has been studied in the temperature range 308–348°K with data points covering the whole conversion range. The results have been analyzed according to the neighbouring-group model with rate constants k₀, k₁, and k₂ for reaction of pyridyl groups with zero, one, and two already reacted neighbors. Allowing for limiting reaction at about 95%, the experimental results substantiate the model with K = k₁/k₀ = 0.80 ± 0.03, and L = k₂/k₀ = 0.37 ± 0.03, which are independent of temperature. The temperature dependence of k₀ values gives an activation energy of 66.22 ± 4.20 kJ mol^?1. It is still not possible to decide whether steric or electrostatic factors are responsible for K and L values less than unity. Other systems are mentioned where side reactions occur.     

Charge mosaic membrane with a microstructure of poly(styrene-b-4-vinylpyridine)

Well defined AB and BAB type poly[styrene(ST)-b-4-vinylpyridine(4VP)]s were prepared by anionic living polymerization in tetrahydrofuran (THF) at ?78°C. Casting AB and BAB type poly(ST-b-4VP)s with a composition of about 50 mol% PST from 1,1,2-trichloroethane (TCE) produced specimens with lamellar microdomain structures. Quaternization of P4VP and sulfonation of PST domains (lamellar and spherical structures), accompanied by each domain fixing, were carried out under various reaction conditions. The piezodialysis of the prepared charge mosaic membrane with its lamellar microdomain structure was measured from a sodium chloride (NaCl) aqueous solution. The results are discussed in some detail.