Ionic conductivity of poly(2-vinyl pyridinium) salt in solid state

The preparation, characterization and conductivities of poly(2vinylpyridine), P-2VP and its fluoride derivative are reported here. The polymer P-2VP was prepared by thermal polymerization of 2vinylpyridine, 2VP and its salt, by acidification with HF. The formation of P-2VP salt was confirmed by IR and ¹H NMR techniques. Conductivities were determined from 30 to 110 °C in solid state. The addition of F⁻ ion increases the ionic conductivity of the polymer dramatically. The P-2VP-HF behaves as an intrinsic conducting polymer. The determination of the molecular mass of P-2VP and P-2VP-HF indicated that 95% of pyridine molecule was hydrofluorinated.     

Conformation of oligo(ethylene glycol) grafted poly(norbornene) in solutions: A small angle neutron scattering study

The conformation of newly synthesized amphiphilic poly(methoxyoligo(ethylene oxide) norbornenyl esters) macro-homopolymers in dilute solutions of toluene-d8 and D₂O was investigated by small angle neutron scattering (SANS). The macro-homopolymers consist of a polynorbornene (PNB) backbone with a degree of polymerization (DP) of 50, and each repeat unit has a grafted ethylene glycol (EG) side chain with an average DP of 6.6. The hydrophobic backbone and hydrophilic side chains interact differently with solvents of different polarity, which makes the polymer conformation very sensitive to the solvent quality. It was found that in a 0.5 wt.% toluene solution the polymers assume coil-like conformation and gradually contract and become more compact with increasing polymer concentration. In D₂O, the conformation of the polymers were studied at different concentrations: 0.1, 0.5, 1.0 and 2.0 wt.% and at different temperatures: 25, 44, 60 and 74 °C. The polymers are partially contracted in D₂O and their shape can be described by the form factor of a rigid cylinder. The second virial coefficient A₂ was extracted at three temperatures (25, 44 and 60 °C) and the theta point was estimated to be reached at ∼45 °C. The attractive interactions between the polymers in D₂O increase with temperature, which leads to the polymer-solvent phase separation at the cloud point temperature (CPT). The polymer conformation remains virtually temperature independent below the CPT and at 74 °C polymers collapse and form compact structures with water soluble side chains in the shell.     

Reversible temperature-induced transformations of poly(N-ethyl-4-vinylpyridinium) complexes with dodecyl sulfate in aqueous salt solutions

Supramolecular organization of complexes formed by poly(N-ethyl-4-vinylpyridinium bromide) and sodium dodecylsulfate in aqueous salt solutions was studied as a function of temperature and concentration of the complexes. It was shown that a decrease in temperature and/or concentration of complexes led to their reversible disaggregation into a molecularly dispersed (“unipolymer”) state. The ratio between the components in complex particles remained unchanged in this case. It was first found that phase separation in aqueous solutions of the complexes upon temperature elevation is accompanied by the precipitation of a nonstoichiometric complex.     

Effect of association processes on polymerization of N-[3-(dimethylamino)propyl]methacrylamide salts in aqueous solutions

The effect of associative interactions of monomers and propagating macroradicals in homopolymerization of N-[3-(dimethylamino)propyl]methacrylamide salts and their copolymerization with acrylonitrile and acrylamide in aqueous solution was studied.     

Amphiphilic cationic [dendritic poly(L-lysine)]-block-poly(L-lactide)-block-[dendritic poly(L-lysine)]s in aqueous solution: self-aggregation and interaction with DNA as gene delivery carriers

A new series of triblock [dendritic poly(L-lysine)]-block-PLLA-block-[dendritic poly(L-lysine)]s (DL(2) -PLLA-DL(2) ) with PLLA block lengths of 11.5-26.5 and double 2-generation PLL dendrons DL(2) as model cationic amphiphiles were synthesized and characterized. Their CAC, self-aggregation and plasmid DNA binding affinities in pure water and PBS were studied. The PLLA block length dependence of particle size, morphology and ξ potential for organized pDNA/amphiphile polyplex aggregates were examined. Finally, toxicities of these DL(2) -PLLA-DL(2) amphiphiles and their polyplexes were assayed by MTT with HeLa, SMMC-7721 and COS-7 cells, and COS-7 cell luciferase and eGFP gene transfection efficacies with these amphiphiles as the delivery carriers were investigated.     

Interaction of cetyltrimethylammonium bromide and poly(2-(acrylamido)-2-methylpropanesulfonic acid) in aqueous solutions determined by excimer fluorescence

 The binding interaction of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic poly(2-(acrylamido)-2-methylpropanesulfonic acid) (PAMPS) in dilute aqueous solutions was studied using the excimer fluorescent emission of the cationic probe 1-pyrenemethylamine hydrochloride (PyMeA·HCl). In the absence of CTAB, the saturation binding of PyMeAH⁺ on PAMPS is about 2.4 AMPS repeat units for one probe cation as determined by the relative emission intensity, I _E/I _M, of the excimer to monomer. With increasing CTAB concentration, I _E/I _M firstly increases, reaches a maximum, then decreases to zero. The I _E/I _M maximum indicates a critical aggregation concentration (cac) of 10⁻⁵ mol/l for CTAB in PAMPS solutions. The CTAB concentration at which I _E/I _M is zero is exactly equal to the PAMPS concentration, indicating that the probe cation is thoroughly excluded from the binding site of PAMPS by the CTAB cation and the equivalent stoichiometric aggregation is formed between CTAB and PAMPS. The blueshift of the excimer emission and the excitation spectra shows that the decrease of I _E/I _M with increasing CTAB concentration above the cac is caused mainly by the decrease of the static excimer. Received: 26 July 2000 Accepted: 23 November 2000     

Synthesis and thermal behaviours of side-chain liquid-crystalline poly[N-(4-methoxyazobenzene-4′-oxyalkyl)ethyleneimine]

A series of side-chain liquid-crystalline polymers, poly[N-(4-methoxyazobenzene- 4′-oxyalkyl)ethyleneimine](PEnZO), has been synthesised in which the number of methylene units in spacers varies from two to six. The structures of the synthesised monomers and polymers were confirmed by infrared (IR) and ¹H nuclear magnetic resonance (¹H NMR) spectroscopy. The thermal properties of these polymers have been investigated using differential scanning calorimetry (DSC), polarising optical macroscopic (POM) X-ray diffraction and thermogravimetric analysis (TGA). The test results indicated that the obtained polymers exhibited thermotropic liquid-crystalline mesomorphism of nematic type with schlieren textures. It was observed that the thermal behaviours of the polymers were strongly dependent on the degree of substitution and the length of spacers. Polymers containing less than 57% of mesogenic groups did not exhibit mesogenic phase and resembled amorphous polymer. A more pronounced odd–even effect in the melting points and their enthalpy changes was observed on increasing the spacer length in which the odd members displayed lower values, which were also slightly dependent on the substitution degree of polymers. The mesomorphic temperature ranges of odd members were wider than those of even members. The decomposition temperatures of copolymers were near 230°C.     

Effects of inorganic salts on the properties of aqueous poly(vinylpyrrolidone) solutions

Cloud point curves and temperatures have been determined for aqueous solutions of poly(vinylpyrrolidone) at several concentrations for a variety of inorganic salts (phosphates, monohydrogen phosphates, sulfates, carbonates, dihydrogen phosphates and fluorides). The resulting dependency of the critical temperatures (mostly between 289 and 350 K) on the molar concentration can be expressed as sequences showing the decreasing effect of anion species or cation species in salting out the polymer. The decreasing order of effectiveness of the anions in reducing the temperatures is PO ₄ ^3– >HPO ₄ ^2– >SO ₄ ^2– CO ₃ ^2– >H₂PO ₄ ^– >F^–. The order for cation is Na⁺>K⁺. The changes brought about in temperatures by the salts were found to be the results of the changes taking place in the hydrophilic and hydrophobic interactions among polymer, solvent and additive salts and of the change of water structure by structure making or structure breaking ions, and of the influence of salts on the hydration sheath of the polymer.Deceased     

Thermosensitivity of optically active hydrogels constructed with N-(L)-(1-hydroxymethyl)propylmethacrylamide

We previously reported on the water soluble, optically active polymer, poly[N-(L)-(1-hydroxymethyl)propylmethacrylamide] (P(L-HMPMA)), which has lower critical solution temperatures of approximately 30 and 21 degrees C upon heating and cooling, respectively. The phase separation behavior of the P(L-HMPMA)-water binary system has a reversible and clear hysteresis during heating and cooling cycles. The present study describes the thermosensitive properties of the optically active polymer and its hydrogel. Circular dichroism and microcalorimetric measurements of the polymer in water supported the hypothesis that the soluble polymer chains might be compactly folded with an interaction between optically active side chains. In addition, these measurements showed the polymer chains in a state of relatively low hydration compared to that of P(D,L-HMPMA), which was free-radically synthesized from racemates of monomers. The solution properties reflected the swollen-shrunken behavior of corresponding hydrogels in response to temperature changes. The microscopic observation of aqueous polymer solutions and hydrogels also confirmed that the optically active properties of polymer chains affect their structure and thermosensitivity. SEM micrograph of the surfaces of the crosslinked P(L-HMPMA).     

Effect of smectogenicity of the ionic groups on the thermotropic liquid crystalline behavior of pyridinium and poly(4-vinylpyridinium) salts quaternized with mesogenic groups

In order to demonstrate the important smectic power of the ionic functions present in mesogenic molecules, a series of N-alkylpyridinium bromides ω-substituted with (4-cyanobiphenylyl)oxy or [4-(2-methyl-1-butoxy)biphenylyl]oxy mesogenic group and their analogous 4-vinylpyridinium polymers were synthesized and characterized. The liquid crystalline behavior was studied by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. Smectic mesophases, namely A, B, and E, were identified for the low molecular weight compounds, whereas smectic A and E mesophases were identified for the analogous polymers. Both structures were found to be very similar. They consist of single layers of upright molecules laterally arranged head-to-tail; the polymer backbone is inserted in between the layers. The monolayer smectic ordering observed in spite of the presence of the interacting cyano and chiral groups demonstrates the prevailing effect of the electrical interactions upon the structural organization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2569–2577, 1997     

Interactions of poly(2-methacryloyloxyethyl phosphorylcholine) with various salts studied by size exclusion chromatography

The objective of this research is to develop a relationship between salt type and concentration to poly(2-methacyloyloxyethyl phosphorylcholine) (PMPC) zwitterionic polymer solution behaviors. In particular, polyelectrolyte hydrodynamic volumes were analyzed through size exclusion chromatography in relation to the addition of various salts at various concentrations. The salt properties examined were salt concentration, ionic strength, solution pH, cation type/size, anion type/size, valency, and configuration. It was found that the effect of ion properties is related to mechanisms associated with the geometry of the polyelectrolyte. The negative charge group of the polyelectrolyte situated closer to the backbone (inside) is less important to the change in hydrodynamic volume than the positive charge group situated at the end of the side chain (outside). The extensive amount of data generated in this study provides a strong background for possible accurate formulation of a theory based on the salt effect on PMPC polyelectrolyte solution behavior.     

Viscosimetric behaviour of hydrolyzed polyacrylamide-poly(4-vinylpyridine) [AD37-P4VP] mixture in aqueous solution

The interactions between 27% hydrolyzed polyacrylamide [AD37] and poly(4-vinylpyridine) [P4VP], in aqueous solutions and at neutralization degree α = 1, were studied by using viscosimetry technique.The reduced viscosities of these copolymer mixture solutions, at 25 °C, reach several orders of magnitude higher than the reduced viscosity of each polymer taken separately, and according to the ratio R of the chain numbers.Intermolecular electrostatic associations are favoured by increasing the P4VP concentration corresponding to high R values. Thus, mixtures rich in P4VP are characterized by a high decrease in the viscosity due to interpolymer complete complexation AD37-P4VP, leading to the totally contraction or collapse of the polymer chains. Strongest reduced viscosities, due to the inter-chain AD37 associations, are observed for the mixtures poor in P4VP (so the weakest ratios R of the chain numbers).In order to understand the relative effects of these two polymers on the reduced viscosity, two mixtures containing the same total quantity are compared. Reduced viscosities of each copolymer alone strongly increase by dilution of the aqueous solution. In the case of the mixture, an opposite behaviour is observed with a reduction in the reduced viscosity by dilution. So, the increase of the reduced viscosity according to AD37 concentration, at α constant, shows an intra and an inter-chain associative phenomenon.     

Self-organization in aqueous solutions of thermosensitive statistical copolymers based on N-(dimethylamino)ethyl methacrylate

Thermo- and pH-responsive statistical copolymers of N-(dimethylamino)ethyl methacrylate and lauryl methacrylate were synthesized by free radical copolymerization. Obtained samples differed in content of hydrophobic components (3 and 6?mol. %). Their molar masses were close to 30,000?g/mol. Self-organization in buffer solutions of copolymers were studied using light scattering and turbidimetry. It was found that copolymers as well as of poly(N-(dimethylamino)ethyl methacrylate) were thermosensitive at pH?>?7. Phase separation temperatures of investigated solutions decreased with dilution and pH increasing. Growth of lauryl methacrylate content in copolymers caused the decrease in phase separation temperatures.     

Formation of poly(ethylene glycol) inclusion complexes in aqueous solutions of mixed cyclodextrins

Even though the addition of modified cyclodextrins (modified CDs) accelerates the precipitation in aqueous solutions of poly(ethylene glycol) (PEG) and α-cyclodextrin (α-CD) the final amount of formed solid complex remains unchanged, with no significant presence of modified CDs detected by MALDI-TOF mass spectrometry. Thus unsuitability of kinetic turbidity measurements for determination of binding parameters was confirmed. On the other hand, theoretical calculations based on a model of a chain of freely accessible binding sites demonstrated that the results do not necessarily contradict the finding that individual modified CD molecules can thread onto PEG chains with the efficiency comparable to that of natural (unmodified) α-CD.     

Behavior of thermoresponsive ionogenic poly(2-isopropyl-2-oxazoline) stars and their mixture in aqueous solutions

Star-shaped eight-arm poly(2-isopropyl-2-oxazoline)s with basic and acidic groups were synthesized using a “grafting from” approach. Molar masses were 13,700 and 14,900?g mol^?1 for polybase and polyacid, respectively. The aqueous solutions of synthesized polymers and their mixture were investigated by the light scattering and turbidimetry methods within wide range of temperatures and pH values. It was shown that the studied polymers separately do not exhibit pH-sensitivity due to the low content of ionogenic groups. For the solutions of mixture, one phase transition was detected, the onset temperature T₁ of which lies between the phase separation temperatures for polymers. The value of T₁ for mixture decreases with increasing acidity of the medium.     

Effects of salts and copolymer composition on the lower critical solution temperature of poly(methyl 2‐acetamidoacrylate‐co‐methyl methacrylate) solutions

Copolymerizations of methyl 2‐acetamidoacrylate (MAA) with methyl methacrylate (MMA) were carried out at 60 °C in chloroform. Copolymers containing MAA units in the range of 83–90 mol % exhibited a lower critical solution temperature (LCST), although homopolymers of MAA and MMA did not. The LCST of polymer solutions decreased with (1) an increase in the concentration of the copolymer, (2) a decrease in the MAA content in the copolymer, and (3) an increase in the concentration of salts added. The effectiveness of anionic species for reducing the LCST is NO < Cl^? < SO < SO. Divalent anion is more effective for lowering the LCST than monovalent anion. However, there is no difference between cationic species in the salting‐out effect. Sodium carbonate and sodium phosphate had a salting‐in effect. Salting‐out coefficients were evaluated from the relationship between the logarithm of solubility of the copolymers and the salt concentration. Salting‐out coefficients of the copolymer depended not on the composition of the copolymers but on the salt added. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1945–1951, 2002     

Side-chain liquid crystalline polymers: The synthesis and characterization of poly[4-nitrothiophenyl-4-(ω-methacryloyl oxyalkyloxy)] benzoate

A new series of sulfur-containing side-chain liquid crystalline polymer is described. Mesomorphic side chains with methylene spacers of different lengths have been synthesized, and their structures were identified by nuclear magnetic resonance, infrared and mass spectrometry. The liquid crystalline nature of the polymers was characterized by microscopy and differential scanning calorimetry.