Organic-inorganic hybrid hydrogels based on linear poly(N-vinylpyrrolidone) and products of hydrolytic polycondensation of tetramethoxysilane

The initial stage of gelation of organic-inorganic hybrid hydrogels based on poly(N-vinylpyrrolidone) and the products of hydrolytic polycondensation of tetramethoxysilane has been studied by capillary viscometry. The development of strong bonds between polymer molecules and silica particles in aqueous solutions is proved by the electrokinetic sonic amplitude method. The molecular mass of poly(N-vinylpyrrolidone), the concentration of starting components, and their total amount affect the onset time of gelation in poly(N-vinylpyrrolidone)—water—tetramethoxysilane systems. The general scheme of formation of three-dimensional networks in such systems under the conditions of mutual penetration of poly(N-vinylpyrrolidone) coils is suggested. According to this scheme, nanoparticles of the general formula SiO _x (OH) _y (OR) _z linking poly(N-vinylpyrrolidone) macromolecules serve as junctions of the gel network due to the formation of hydrogen bonds between hydrogens of silanol groups of organosilanes and oxygens of carbonyl groups of poly(N-vinylpyrrolidone).     

Interaction of copper nanoparticles with liposomes

The reduction of copper(II) ions in an aqueous dispersion of positively charged liposomes results in the formation of stable sols of a complex of copper nanoparticles with the surface of liposomes. The mean size (7 nm) and the narrow size distribution of metal nanoparticles are similar to those observed in the case of metal sol formation in polymer solutions. The labile character of bonds between nanoparticles and liposomes makes the latter able to compete with a linear polymer (poly-N-vinylpyrrolidone) in binding to nanoparticles. This ability is manifested in the independence of an almost even distribution of nanoparticles between these competitors from the sol preparation mode in a system including both poly(N-vinylpyrrolidone) macromolecules and liposomes. The evenness of the distribution indicates an approximately identical stability of complexes of copper nanoparticles with both competitors. The replacement of liposomes with poly(N-vinylpyrrolidone) macromolecules in the protective shields of nanoparticles is accompanied by the detachment of the nanoparticles from the surface, thereby allowing the measurement of their size and size distribution in the case where such measurements are impossible because of a high density of nanoparticles on the liposome surface.     

Water-soluble complexes of poly(N-vinylamides) of various structures with C60 and C70 fullerenes

By the example of the interaction of fullerene C₆₀ and poly(N-vinylpyrrolidone), the effect of formation conditions of water-soluble fullerene-containing donor-acceptor polymer systems on their composition and structure has been studied. On the basis of these results, a new technique has been developed for preparing water-soluble polymer systems of this kind with the use of o-dichlorobenzene as a component of the reaction medium. This technique has been employed to prepare water-soluble fullerene-containing complexes of poly(N-vinylamides) of various structures (polymers and copolymers of N-vinylpyrrolidone and N-vinylcaprolactam) containing up to 3–5 wt % of C₆₀ and C₇₀ fullerenes. These values are 3–6 times higher than those described previously.     

Synthesis of poly(N-vinylpyrrolidone) and N-vinylpyrrolidone-methyl methacrylate copolymers in the presence of C-phenyl-N-tert-butylnitrone

The free-radical polymerization of N-vinylpyrrolidone and its copolymerization with methyl methacrylate have been studied at 60°C in the presence of C-phenyl-N-tert-butylnitrone as a chain-growth regulator. It has been shown that the above additive makes it possible to synthesize poly(N-vinylpyrrolidone) and its copolymers without any gel effect and to control molecular-mass characteristics of homo-and (co)polymers.     

Competition between polyelectrolyte macromolecules and amphiphilic polymer micelles in interaction with copper nanoparticles

Competition between poly(1,2-dimethyl-5-vinylpyridinium methyl sulfate) polycationic macromolecules and micelles of amphiphilic polymers containing hydrophilic and hydrophobic blocks (polyethylene glycol-600 monolaurate and poly-N-vinylpyrrolidone monostearate) for copper nanoparticles was studied by means of electrophoresis and electron microscopy techniques. It was shown that, irrespective of the formation method, almost all copper nanoparticles were bonded to the polycation in polycation-polyethylene glycol-600 monolaurate mixed solutions but were distributed between the polymers in polycation-poly-N-vinylpyrrolidone monostearate mixtures. It was concluded that the stability of the complex of copper nanoparticles with the polycation is higher than that with polyethylene glycol-600 monolaurate and is comparable with that of the copper particle-poly-N-vinylpyrrolidone monostearate complex.     

Synthesis of Poly(arylene ether amide)s Containing CF3 Groups by Nitro Displacement Reaction of AB‐Type Monomers

New poly(arylene ether amide)s with trifluoromethyl pendent groups were prepared via nucleophilic nitro displacement reaction of AB‐type monomers. 4‐Nitro‐3‐trifluoromethyl‐[N‐(4‐hydroxyphenyl)]benzamide ( 3 ) and 4‐nitro‐3‐trifluoro‐methyl‐[N‐(3‐hydroxyphenyl)]benzamide ( 4 ) gave polymers with weight‐average molecular weights over 42 000 g/mol and glass transition temperatures of 269°C and 213°C, respectively. Both polymers were soluble in common organic solvents including THF, and formed transparent films upon casting.     

Influence of the Molecular Mass of Poly(<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone) on Formation of Cu<Subscript>2</Subscript>O Nanoparticles During Reduction of Divalent Copper Ions with <Emphasis Type="Italic">tert</Emphasis>-Butylamine Borane in Polymer Solution

The process of reduction of divalent copper ions with tert-butylamine borane in dilute aqueous solutions of poly(N-vinylpyrrolidone) is investigated. The influence of polymer molecular mass on properties of the resultant Cu₂O sols is studied. It is shown that Cu₂O nanoparticles with an average diameter of 6–8 nm independent of polymer molecular mass and a relatively narrow size distribution of particles are formed in the systems under study. The contour length of macromolecules and the hydrodynamic diameter of a poly(N-vinylpyrrolidone) macromolecular coil are compared with the diameter of Cu₂O particles. Poly(N-vinylpyrrolidone) with M ≥ 1 × 10⁴ can be used to produce Cu₂O nanoparticles. Poly(N-vinylpyrrolidone) with M > 4 × 10⁴ should be used for the formation of long-living Cu₂O sols.     

New soluble, thermally stable poly(amide-imide)s containing cardo anthraquinone unit

Preparation of new types of polyimides with high thermal stability and improved solubility was considered. In this way, two new amide diamines containing bulky pendant units were prepared in two steps: nucleophilic substitution reactions of 1- and 2-aminoanthraquinone with 3,5-dinitrobenzoyl chloride to form amide containing dinitro compounds, and then reduction of resulted dinitro compounds with hydrazine monohydrate in the presence of palladium/activated carbon. Two series of new poly(amide-imide)s were prepared from the reactions of these two diamines with various dianhydrides by one step polyimidation process. All poly(amide-imide)s were characterized by FTIR and ¹H-NMR spectroscopies and elemental analysis. The polymers were obtained in high yields with inherent viscosities of 0.54-0.69 dl g⁻¹. X-ray diffraction patterns (XRD) showed that all the polymers were amorphous and therefore this factor in addition to the introduction of bulky anthraquinone group led to good solubility of the polymers in most common organic solvents especially in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and dimethylsulfoxide (DMSO). Thermal analysis showed glass transition temperature between 204 and 226 °C. Decomposition temperatures were more than 293 °C, also 10% weight loss were in the range of 387-419 °C in air.     

Synthesis and characterization of novel heat resistant poly(amide imide)s

A series of new poly(amide imide)s was prepared from new diacid containing sulfone, ether, amide and imide groups with various aromatic diamines. The diacid was synthesized via four steps, starting from reaction of 4-aminophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide afforded N-(4-hydroxy phenyl)-4-nitrobenzamide. In the second step, reduction of nitro group resulted in preparation of 4-amino-N-(4-hydroxy phenyl) benzamide. In the next step for the preparation of diamine, the reaction of 4-amino-N-(4-hydroxy phenyl) benzamide with bis-(4-chlorophenyl) sulfone in the presence of K₂CO₃ was achieved. The prepared sulfone ether amide diamine was reacted with two moles of trimellitic anhydride to synthesize related sulfone ether amide imide diacid. The precursors and final monomer were characterized by FT-IR, H-NMR and elemental analysis. Direct polycondensation reaction of the sulfone ether amide imide diacid with different diamines in the presence of triphenyl phosphite afforded five different poly (sulfone ether amide imide amide)s. The obtained polymers were fully characterized and their physical properties including thermal behavior, thermal stability, solubility, and inherent viscosity were studied.     

Synthesis,characterization and the rapid response property of the temperature responsive PVP-g-PNIPAM hydrogel

In this study, a poly(N-vinylpyrrolidone)-graft-poly(N-isopropylacrylamide) hydrogel (PVP-g-PNIPAM) was synthesized through the “grafting from” process. Grafting of temperature responsive poly(N-isopropylacrylamide) (PNIPAM) brushes was carried out from the poly(N-vinylpyrrolidone) (PVP) synthesized with free radical polymerization and functionalized with ATRP initiator, PVP–Br, which was performed through a bromination reaction between pendant allylic groups of the PVP and N-bromosuccinimide (NBS). The structure of the initiator and PVP-g-PNIPAM was characterized by ultraviolet and visible (UV/Vis) absorption, nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FTIR) measurements. Scanning electron microscope (SEM) morphology measurement displayed some dendritic grafted chains dangling onto the pore wall of the hydrogel.The characteristic in response to the change in environmental temperature was investigated by the fluorescence anisotropy and UV/Vis transmittance measurements. The results showed that the PVP-g-PNIPAM hydrogel exhibited rapid response to the change in environmental temperature due to free and mobile graft chains compared with the P(VP-co-NIPAM) hydrogel, which was prepared by free radical copolymerization in this work.     

Aromatic poly(sulfone sulfide amide imide)s as new types of soluble thermally stable polymers

A new diamine monomer containing flexible sulfone, sulfide, and amide units was prepared via three steps. Nucleophilic chloro displacement reaction of 4‐aminothiophenol with 4‐nitrobenzoyl chloride in the presence of propylene oxide afforded N‐(4‐mercapto‐phenyl)‐4‐nitrobenzamide and subsequent reduction of the nitro intermediate led to 4‐amino‐N‐(4‐mercapto‐phenyl)benzamide. Two moles of this amino thiophenol compound was reacted with bis‐(4‐chloro phenyl)sulfone to provide a novel diamine monomer. The diamine was reacted with aromatic dianhydrides to form polyimides via a two‐step polycondensation method, formation of poly(amic acid)s, followed by chemical imidization. The resulting polymers were characterized and their physical properties including thermal behavior, thermal stability, solubility and inherent viscosity were studied. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis and photoluminescent and electrochromic properties of aromatic poly(amine amide)s bearing pendent N‐carbazolylphenyl moieties

A series of novel poly(amine amide)s ( IIa – IIl ) with pendent N‐carbazolylphenyl units having inherent viscosities of 0.25–1.06 dL/g were prepared via direct phosphorylation polycondensation from various dicarboxylic acids and a carbazole‐based aromatic diamine. Except for poly(amine amide) IIc , derived from trans‐1,4‐cyclohexanedicarboxylic acid, all the other amorphous poly(amine amide)s were readily soluble in many polar solvents, such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone (NMP), and could be cast into transparent and flexible films. The aromatic poly (amine amide)s had useful levels of thermal stability associated with relatively high glass‐transition temperatures (268–331 °C), 10% weight loss temperatures in excess of 540 °C, and char yields at 800 °C in nitrogen higher than 60%. These polymers exhibited maximum ultraviolet–visible absorption at 293–361 nm in NMP solutions. Their photoluminescence in NMP solutions exhibited fluorescence emission maxima around 362 and 448–499 nm for aromatic–aliphatic poly(amine amide)s IIa – IIc and aromatic poly (amine amide)s IId – IIl , respectively. The fluorescence quantum yield in NMP solutions ranged from 0.34% for IIj to 4.44% for IIa . The hole‐transporting and electrochromic properties were examined with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of the poly(amine amide) films cast onto an indium tin oxide coated glass substrate exhibited reversible oxidation at 0.81 V and irreversible oxidation redox couples at 1.20 V versus Ag/AgCl in acetonitrile solutions, and they revealed excellent stability of the electrochromic characteristics, with a color change from yellow to green at applied potentials ranging from 0.00 to 1.05 V. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4108–4121, 2006     

Novel water-soluble fluorescent polymer containing recognition units: Synthesis and interactions with PC12 cell

New water-soluble fluorescent poly(N-vinylpyrrolidone) (PVP) containing carbonylhydrazide recognition units was synthesized by free radical polymerization of N-vinylpyrrolidone in the presence of mercaptoacetic acid as chain transfer agent and then being modified by 1-pyrenebutyric acid hydrazide. FT-IR, ¹H NMR, gel permeation chromatography-multi-angle laser light scattering and fluorescence spectroscopy were used to characterize these polymers. Results of fluorescence measurements show that these polymers have a good affinity for deoxyribonucleic acid (DNA). The interactions with PC12 cell results indicated that the polymer with suitable molecular weight could penetrate into PC12 cell and emit fluorescence. This water-soluble polymer with recognition units and high luminescence can be used as a promising fluorescent probe for measurements of biomacromolecules and cells.     

Interpolymer complexes of poly(N-vinylpyrrolidone) with copolyimide-grafted side chains of poly(methacrylic acid)

The process of formation and structural organization of interpolymer complexes formed by macromolecules of poly(N-vinylpyrrolidone) and poly(methacrylic acid) chains grafted onto polyimide in solution is investigated via the method of polarized luminescence. A luminescent label of anthracene structure is covalently bound to both polymers. Relaxation times characterizing intramolecular mobility of each of the components in their interpolymer complex are measured in relation to the composition of the system.     

Synthesis and properties of new soluble triphenylamine‐based aromatic poly(amine amide)s derived from N,N′‐bis(4‐carboxyphenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new triphenylamine‐containing aromatic dicarboxylic acid, N,N′‐bis(4‐carboxyphenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was synthesized by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 4‐fluorobenzonitrile, followed by the alkaline hydrolysis of the intermediate dinitrile compound. A series of novel triphenylamine‐based aromatic poly(amine amide)s with inherent viscosities of 0.50–1.02 dL/g were prepared from the diacid and various aromatic diamines by direct phosphorylation polycondensation. All the poly(amine amide)s were amorphous in nature, as evidenced by X‐ray diffractograms. Most of the poly(amine amide)s were quite soluble in a variety of organic solvents and could be solution‐cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with glass‐transition temperatures up to 280 °C, 10% weight‐loss temperatures in excess of 575 °C, and char yields at 800 °C in nitrogen higher than 60%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 94–105, 2003     

Flow birefringence and optical anisotropy of poly(N-vinylpyrrolidone) molecules

Concentration dependences of flow birefringence and viscosity of poly(N-vinylpyrrolidone) solutions in water and benzyl alcohol are investigated. The intrinsic anisotropy for a poly(N-vinylpyrrolidone) macromolecular segment, (α₁ ? α₂) = ?(82 ± 8) × 10^?25 cm³, is determined from the results of birefringence measurements in benzyl alcohol. For aqueous solutions, a strong concentration dependence of the specific anisotropy of solution is obtained, a result that may be explained by the heterogeneity of coils. A model allowing for this heterogeneity is suggested. It makes it possible to fit the concentration dependence to a hyperbolic function, to separate contributions of heterogeneity anisotropy and form anisotropy to the birefringence of a solution, and to estimate the segment asymmetry parameter as p = 3.0 ± 0.5.     

Synthesis and properties of new soluble aromatic polyamides and polyimides on the basis of N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new N‐phenylated amide (N‐phenylamide) unit containing aromatic diamine, N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 3‐nitrobenzoyl chloride, followed by catalytic reduction. Two series of organosoluble aromatic poly(N‐phenylamide‐imide)s and poly(N‐phenylamide‐amide)s with inherent viscosities of 0.58–0.82 and 0.56–1.21 dL/g were prepared by a conventional two‐stage method and the direct phosphorylation polycondensation, respectively, from the diamine with various aromatic dianhydrides and aromatic dicarboxylic acids. All polyimides and polyamides are amorphous and readily soluble in many organic solvents such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with high tensile strengths. These polyimides and polyamides had glass‐transition temperatures in the ranges of 230–258 and 196–229 °C, respectively. Decomposition temperatures of the polyimides for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2564–2574, 2002     

Controlled synthesis of poly(acetone oxime acrylate) as a new reactive polymer: Stimuli-responsive reactive copolymers

Acetone oxime acrylate has been synthesized as a new active ester monomer. Free radical polymerization yielded a reactive polymer soluble in various organic solvents, such as chloroform, dioxane, DMSO, acetone, methanol, dichloromethane, DMF, and ethanol. Controlled radical polymerization of acetone oxime acrylate was successfully conducted using the RAFT, NMP and Iniferter method. Partly polymer analogous reaction with N-isopropylamine resulted in the reactive copolymer poly(N-isopropylacrylamide-co-acetone oxime acrylate), which featured a lower critical solution temperature (LCST) of 61 °C in water. Further, the reactivity of the copolymer was exemplary proven by complete reaction with ammonia yielding poly(N-isopropylacrylamide-co-acrylamide), which does not possess a LCST.     

Supramolecular assembly in a polymer/ low-molar-mass system

Thermal analysis and infra-red spectroscopy have been used to study the interactions between poly (N-vinylpyrrolidone) and low-molar-mass, hydrogen-bonding-active aromatics. A remarkably strong interaction is observed between the polymer and 3,5-dihydroxybenzoic acid, which is consistent with the crosslinking of the polymer by acid dimers.     

Synthesis and characterization of novel poly(amide urea)s,materials with outstanding mechanical properties

Four novel A‐B condensation monomers containing an amine and a carboxylic acid function are described, along with their polymerization to give main chain aromatic poly(amide urea)s. The monomers, and the polymer structural unit, are N,N′‐diphenylurea derivatives. When comparing wholly aromatic polyamides, or aramids, with the poly(amide urea)s described herein, we find that the chemical resistance to hydrolysis of the later polymers increases and their thermal resistance is diminished due to the main chain urea groups, whereas their water uptake is not greatly modified. The most striking result of the new poly(amide urea)s is their outstanding mechanical resistance: their Young's modulus rises as high as 5.5 GPa and their tensile strengths as high as 170 MPa for unoriented films prepared at laboratory scale by casting. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5398–5407, 2007