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Facilitated transport membranes have been intensively studied for CO 2 separation and capture, in which amine carriers are the key for membrane separation performance. It has been reported that sterically hindered amines possess superior CO 2 loading capacity over unhindered amines. In this work, we successfully introduced the effect of the steric hindrance to the nitrogen site of amine into polyvinylamine membranes. Sterically hindered poly(N-vinylamine)s, namely poly(N-methyl-N-vinylamine), poly(N-isopropyl-N-vinylamine), and poly(N-tertiary-butyl-N-vinylamine), were synthesized from modifying unhindered poly(N-vinylamine). The effect of steric hindrance on membrane performance was investigated under the typical flue gas CO 2 capture conditions, i.e., 57 °C and ~ 1 atm, showing that poly(N-methyl-N-vinylamine) was the one with the optimal steric hindrance degree for the best membrane performance. Compared with unmodified polyvinylamine, poly(N-methyl-N-vinylamine) demonstrated 24% improvement on CO 2 permeability and 14% increase in CO 2 /N 2 selectivity at 57 °C. The membrane performance enhancement by amine steric hindrance was found to be greatly influenced by temperature. At 102 °C, poly(N-methyl-N-vinylamine) demonstrated a CO 2 permeability of 6804 Barrers, a CO 2 /N 2 selectivity of 350, and a CO 2 /H 2 selectivity of 162, which were approximately 4 times those of unmodified polyvinylamine. This work has extended the study on sterically hindered polyamines for CO 2 facilitated transport and developed a next-generation fixed-site carrier membrane. [ABSTRACT FROM AUTHOR]

Industrial hollow fiber membranes for the purification of wastewater were manufactured by the phase inversion method in a dry-wet spinning process, adding an amphiphilic diblock copolymer to a standard PVDF/Polyvinylpyrrolidone (PVP) formulation. The copolymer designed to provide antifouling properties is composed of a PMMA block and a hydrophilic block bearing pendent hydroxy groups. As PMMA is miscible with PVDF, the copolymer is expected to anchor in the matrix more efficiently than the hydrophilic but water soluble PVP which is washed away overtime during repetitive cleaning procedures. Infrared experiments attest that both antifouling additives are well included in the fibers after the inversion process. Performances of the fibers were checked by permeability, burst pressure and tensile tests. The pore distribution observed by scanning electron microscopy goes from 10 to 30 nm at the outer surface to 0.1–10 µm inside the fiber. Observation of the pore structure by transmission electron microscopy, made possible by embedding the fibers into a resin that filled in the voids, and specific staining of the antifouling additives, shows that both PVP and the amphiphilic copolymer are located all around the pores. This study is the first direct proof at the microscopic scale of pore surface enrichment by antifouling agents. [ABSTRACT FROM AUTHOR]

The structure and electrochemical properties of adsorbed complexes based on mixtures of polyvinylamine-g-TEMPO (PVAm-T) and laccase were related to the ability of the adsorbed complexes to oxidize cellulose. PVAm-T10 with 10% of the amines bearing TEMPO moieties (i.e., DS = 10%), adsorbed onto gold sulfonate EQCM-D sensor surfaces giving a hydrogel film that was 7 nm thick, 89% water, and encasing laccase (200 mM) and TEMPO moieties (33 mM). For DS values >10%, all of the TEMPOs in the hydrogel film were redox-active in that they could be oxidized by the electrode. With hydrogel layers made with lower-DS PVAm-Ts, only about half of the TEMPOs were redox-active; 10% DS appears to be a percolation threshold for complete TEMPO-to-TEMPO electron transport. In parallel experiments with hydrogel complexes adsorbed onto regenerated cellulose films, the aldehyde concentrations increased monotonically with the density of redox-active TEMPO moieties in the adsorbed hydrogel. The maximum density of aldehydes was 0.24 μmol/m2, about 10 times less than the theoretical concentration of primary hydroxyl groups exposed on crystalline cellulose surfaces. Previous work showed that PVAm-T/laccase complexes are effective adhesives between wet cellulose surfaces when the DS is >10%. This work supports the explanation that TEMPO-to-TEMPO electron transport is required for the generation of aldehydes necessary for wet adhesion to PVAm. [ABSTRACT FROM AUTHOR]

Background Uterine fibroid embolization (UFE) is an effective minimally invasive treatment aimed to obtain complete fibroid infarction. Purpose To evaluate the degree of fibroid infarction after embolization with acrylamido polyvinyl alcohol microspheres (Bead Block). Material and Methods This prospective study included 26 pre-menopausal women in the period October 2013 to January 2015. UFE with the use of Bead Block microspheres 700-900 µm was obtained until flow stasis was achieved. Contrast-enhanced magnetic resonance imaging (MRI) was used to define residual contrast enhancement in the total fibroid burden and enhancement >10% was defined as insufficient embolization. The dominant fibroid volume and total uterine volume changes were assessed. Clinical outcome was analyzed using the quality of life questionnaire (UFS-QOL). Results Twenty-four of the 26 patients (92%) had a technically successful UFE with complete flow-stop in both uterine arteries. Twenty-two of the 26 patients (85%) completed 3 months of MRI control and 20 patients (77%) completed 12 months of MRI control. There were 16 of 22 patients (73%) with complete fibroid burden infarction and/or without residual contrast enhancement of the fibroids of more than 10% at 3 months of control. Six of 22 patients (27%) had insufficient fibroid burden infarction with residual contrast enhancement of more than 10%. Twenty-two and 18 of 26 patients completed the 3-month and 12-month questionnaire, respectively. UFS-QOL analyses showed that 91% of the patients had significant clinical improvement. Conclusion Sixteen of the 22 patients had complete fibroid burden infarction using Bead Block microspheres (700-900 µm); however, unacceptably high insufficient fibroid burden infarction in almost one-fourth of the patients were recorded. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gene transfection with polymeric carrier remains a challenge; particularly, high transfection levels combined with low toxicity are hard to achieve. We herein revisit polyvinylamines, an old and neglected family of cationic polymers. They can be readily obtained by controlled hydrolysis of polyvinylamides prepared through (controlled) radical polymerization. A series of tailor-made and well-defined polyvinylamines bearing primary amino groups, and poly(N-methylvinylamine) bearing secondary amines, were evaluated for the transfection of cells with pDNA as a function of their molar mass, molar mass distribution, and degree of deacetylation. Unexpected high transfection levels, in combination with low cytotoxicity were recorded for both series. Surprisingly, a great impact of the molar mass was observed for the primary amine polyvinylamine series, whereas the results were mostly independent of molar mass or dispersity for the polymer bearing secondary amine. It was further established that a certain percentage of acetamide groups increased the transfection level, while maintaining low cytotoxicity. These results highlight for the first time the real potential of polyvinylamines as gene carriers, and make these polymers very attractive for further development in gene therapy. [ABSTRACT FROM AUTHOR]

Highly permeable montmorillonite layers bonded and aligned with the chain stretching orientation of polyvinylamineacid are immobilized onto a porous polysulfone substrate to fabricate aligned montmorillonite/polysulfone mixed-matrix membranes for CO2 separation. High-speed gas-transport channels are formed by the aligned interlayer gaps of the modified montmorillonite, through which CO2 transport primarily occurs. High CO2 permeance of about 800 GPU is achieved combined with a high mixed-gas selectivity for CO2 that is stable over a period of 600 h and independent of the water content in the feed. [ABSTRACT FROM AUTHOR]

Heavy metals are environmental toxins entering in the food chain through drinking water causing serious health hazards. In the present work, surface of polymethyl methacrylate and polyvinyl chloride was functionalized with amine groups using 1,2-ethylenediamine and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and elemental analysis. The resulting polymers polymethacrylamide derivative of 1,2-ethylenediamine (PMAm) and polyvinylamine derivative of 1,2-ethylenediamine (PVAm) were tested for the adsorption of Ni2+and Cd2+ions from water. Effect of various physicochemical parameters such as pH, adsorbent dose, contact time, initial Ni2+and Cd2+ion concentration, and temperature on adsorption of Ni2+and Cd2+ion was investigated. Langmuir and Freundlich isotherm models were used to analyze equilibrium data of adsorption. Monolayer adsorption capacity of PMAm-Ni2+, PMAm-Cd2+, PVAm-Ni2+and PVAm-Cd2+systems was found to be 7.87 mg/g, 10.57 mg/g, 23.92 mg/g, and 31.44 mg/g, respectively. Kinetic studies were performed using pseudo-first-order, pseudo-second-order kinetic models, and intraparticle diffusion method. The spontaneity and nature of adsorption process were determined by thermodynamic parameters, such as change in Gibb’s free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°). [ABSTRACT FROM PUBLISHER]

Contact-active antibacterial materials with irreversibly attached antibacterial agents have been developed as an environmentally friendly alternative to traditional biocide treatments. Of particular interest are materials fabricated through the physical adsorption of charged polymers. This simple method allows for the use of water-based processes and materials originating from renewable sources, e.g., cellulosic fibres. Furthermore, by varying the process parameters, such as ionic strength, it is possible to tune the properties of the adsorbed polymer layer. However, the underlying antibacterial mechanism remains obscure, and this hinders the rational design of antibacterial multilayers. To gain further insight into the antibacterial mechanisms of physically adsorbed multilayers of polyvinylamine and polyacrylic acid, the surface charge of cellulose fibres was increased via radical oxidation. This oxidation increased the amount of polymer that was adsorbed and resulted in increased antibacterial efficacy against both Escherichia coli and Bacillus subtilis compared with polymer-modified unoxidised fibres. Electron microscopy analysis of the E. coli adhered to the fibres revealed that the multilayer treatment resulted in elongated bacteria with deformed cell walls. This work demonstrates the importance of electrostatic interaction to the antibacterial effect of polymer-modified fibres . [ABSTRACT FROM AUTHOR]

In this study, poly(vinyl alcohol) (PVA) films doped with thorium nitrate hydrate [Th(NO3)4] have been prepared using casting technique. The optical absorption spectra were recorded at room temperature in the wavelength range 200-800 nm. From the absorption edge studies, the values of the Urbach energy (Eu) have been evaluated. These energy values vary slightly with composition, indicating that the model based on electronic transitions between localized states is not preferable. Optical parameters such as refractive index and complex dielectric constant have been determined. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model. Color properties of the prepared samples were discussed in the framework of CIE L*u*v* color space. [ABSTRACT FROM AUTHOR]

To develop a high dielectric constant composite of poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] and multi-walled carbon-nanotubes (MWCNTs) with desirable homogeneity, MWCNTs were treated with a nitro-sulfuric acid by ultrasonication. Improvement of the dispersibility of chemically modified MWCNTs (a-MWCNTs) in polymer matrix, in comparison with that of unmodified MWCNTs in P(VDF-TrFE), was confirmed by field emission scanning electron microscopy (FESEM)-observed morphologies. Electric behavior of the composites with different volume fraction of dispersed carbon nanotubes phase can be described mainly by percolation theory. The percolation threshold (fc) of composites with a-MWCNTs (fc=0.0308) is larger than that of composites with MWCNTs (fc=0.0216) due to better dispersion of a-MWCNTs in polymer matrix and the reduction of aspect ratio of a-MWCNTs occurred in the modification procedure. The composite with 2.98 vol% (a volume fraction close to the percolation threshold) of a-MWCNTs has a dielectric constant of 592 at 100Hz and room temperature. The composite remains very flexible with an elastic modulus close to that of the parent copolymer. [ABSTRACT FROM AUTHOR]

The adsorption of amino-functionalized poly(methyl methacrylate) particles prepared by emulsion polymerization onto polyamide/elastane fibres was investigated. The influence of several physicochemical parameters (pH, ionic strength) on the colloidal stability and surface properties of the cationic latex particles was first examined. Then, particle adsorption was studied as a function of particle concentration, particle size, time, pH and salinity. The results obtained demonstrated that the adsorption process was mainly governed by electrostatic interactions and the adsorption isotherms were analysed on the basis of a Langmuir model. Finally, the effect of washing steps on the adsorbed particles was investigated. The results obtained indicated strong interactions between particles and textile fibres. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: Highly effective piezoelectric polymer transducers operating in air at high frequencies have been successfully made by casting a solution of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) P(VDF/TrFE) directly on a backing metal plate, and their performance has been evaluated. By utilizing this method, it has been possible to develop the three kinds of transducers that operate respectively at 4, 6 and 10MHz in air. For precise evaluation of the performance of the P(VDF/TrFE) transducers, the absorption loss in air was measured up to 10MHz. It was confirmed that the empirical formula obtained from the measured absorption values in air at high frequencies was in alignment with its theoretical value. In addition, a high lateral resolution acoustic image of a ROM-Chip (amplitude-image) at 6MHz in air was successfully displayed using an air coupled concave type P(VDF/TrFE) transducer by bonding an epoxy adhesive. [Copyright &y& Elsevier]

The origin of the strong adhesion between wet, regenerated cellulose film and phenylboronic acid derivatives of polyvinylamine was investigated. The main conclusion was that the phenylboronate groups form weak complexes with the oxidizing ends of cellulose chains in the regenerated cellulose films. There was no evidence that the boronate condensed with hydroxyl groups along the cellulose backbone. [ABSTRACT FROM AUTHOR]

Cationic polymer charge and polymer degradability each play a crucial role for packaging and delivering plasmid DNA. High density cationic charge has been shown to enhance transfection efficiency but may give rise to undesirable toxicity. Polyvinylamine PVAm nanogels bearing discrete amounts of surface charge were used to systematically examine the balance between transfection efficiency and cytotoxicity. PolyNvinylformamide PNVF nanogels were prepared via an inverse emulsion polymerization reaction and crosslinked with a nondegradable or acidlabile crosslinker. The nanogels were then hydrolyzed to yield varying degrees of primary amines. The degree of conversion from PNVF to PVAm was controlled using different concentrations of NaOH and hydrolysis times. PVAm nanogel size and charge ranged from 150 to 310 nm, and 3.5 to 18 mV, respectively. These cationic particles were then complexed with pDNA encoding for luciferase. The cytotoxicity of PVAm nanogels and the transfection efficiency of PVAmDNA complexes were evaluated in carcinomic human alveolar basal epithelial cells A549. The cytotoxicity of PVAm nanogels increased with increasing accessible charge as expected. Transfection efficiency increased with increasing amounts of amine groups for nondegradable nanogels. Interestingly, acidlabile nanogels bearing low charge demonstrated more sustained gene transfection when compared with the more highly charged nanogels. These observations suggested that the use of degradable particles with less charge may reduce cytotoxicity without compromising overall transfection efficiency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [ABSTRACT FROM AUTHOR]

Abstract: Zinc sulfide semiconductor nanocrystals doped Mn2+ have been synthesized via a solution-based method utilizing optimum dopant concentration (4%) and employing polyvinyl pyrrolidone (PVP) and sodium hexametapolyphosphate (SHMP) as capping agents. UV–vis absorbance spectra for all of the synthesized nanocrystals show an exitonic peak at around 310nm. The particle size and morphology were characterized by scanning electron microscopy (SEM), FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescence spectrum (PL). Diffraction data confirmed that the crystallite size is around 3–5nm. Room temperature photoluminescence (PL) spectrum for the bare ZnS sample shows a strong band at ∼445nm. The uncapped and capped(SHMP, PVP) ZnS:Mn2+ samples show a strong and broad band in the ∼580–585nm range. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study on the electrical properties of crosslinked poly(vinyl amine) (PVAm) hydrogels. The hydrogels were prepared by crosslinking PVAm with copper(II) ions as reticulation agent. The study revealed that complex bonds were formed between the copper(II) ions and the amine groups of PVAm producing a network of crosslinked PVAm-copper(II) composites with a microporous morphology. The composites have potential application as ultrafast water sensors.

This paper describes the concept and design of a novel artificial hair receptor for the sensing system of micro intelligent robots such as a cricket-like jumping mini robot. The concept is inspired from the natural hair receptor of animals, also called cilium or filiform hair by different research groups, which is usually used as a vibration receptor or a flow detector by insects, mammals and fishes. The suspended fiber model is firstly built and the influence of scaling down is analyzed theoretically. The design of this artificial hair receptor is based on aligned suspended PVDF (polyvinylidene fluoride) fibers, manufactures with a novel method called thermo-direct drawing technique, and aligned suspended submicron diameter fibers are thus successfully fabricated on a flexible Kapton. In the post process step, some key problems such as separated electrodes deposition along with the fiber drawing direction and poling of micro/nano fibers to impart them with good piezoeffective activity have been presented. The preliminary validation experiments show that the artificial hair receptor has a reliable response with good sensibility to external pressure variation and, medium flow as well as its prospects in the application on sensing system of mini/micro bio-robots. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we developed a new sensor based on a specially designed polymer–metal complex which has the following characteristics: (i) resistance to dissolution in water, (ii) mechanical toughness, (iii) rapid reaction to humidity changes and (iv) precise pinpointing of a water leakage through simple technology. A hydrogel of polyvinylamine cross-linking with Cu(II) salts is employed as sensing material which has an ultrafast electrical response when it is exposed to water. Employing this composite it is possible to extrude in length continuous cables, which permits the production of actual distributed sensors of several kilometers long, which may survey water leakages or filtrations in a number of civil constructions as; pipelines, buildings, electric power stations, libraries, etc. Three PVAm formulations with different contents of Cu(II) salts were prepared and evaluated. Their cross-linking density was evaluated by viscosimetry and swelling tests, and its effect over morphological, thermal, rheological and electrical properties was evaluated by: SEM, TGA, rotatory rheometry and four probe resistivity measurements. A distributed water sensor prototype was prepared with PVAm–Cu(II) and its capability to detect and pinpoint water leakages was assessed. Experimental results showed that this sensor has an excellent performance on monitoring long water pipelines. [Copyright &y& Elsevier]

A drop tower was used to identify the mechanical behaviors of two polyvinyl acetate-polyethylene (PVA-PE) polymers and one elastomer used to fabricate custom-made mouthguards. The samples were in the form of either small cubes (edge length: 20 mm) or large cubes (edge length: 30 mm). Force and strain were recorded as functions of time, enabling a stress-strain analysis to be performed. In addition, a volume energy analysis was performed. While the three materials were viscoelastic, the stress-strain analysis showed that the PVA-PE polymers were more rigid than the elastomer, i.e., the same stress was reached with a lower strain. With the volume energy analysis, the two PVA-PE polymers were found to absorb a relatively large amount of energy with small sample deformations. Results of this study suggested that the mechanical properties of PVA-PE polymers are particularly useful and relevant for the fabrication of custom-made mouthguards. [ABSTRACT FROM AUTHOR]

Abstract: Spinel Li4Ti5O12/C powders were synthesized successfully by a simple rheological phase method using polyvinylbutyral (PVB) as both template and carbon source. The structure and morphology characteristics of the composite were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy and transmission electron microscopy. The XRD results showed that the composite had a good crystallinity. Its average particle size was about 2.1μm with a narrow size distribution as a result of homogeneous mixing of the precursors. The in situ carbon coating produced by decomposition of PVB played an important role in improving electrical conductivity, thereby enhancing the rate capacity of Li4Ti5O12 as anode material in Li-ion batteries. The Li4Ti5O12/C composite, synthesized at 800°C for 15h under argon, containing 0.98wt% of carbon, exhibited better electrochemical properties in comparison with the pristine Li4Ti5O12, which could be attributed to the enhanced electrical conductive network of the carbon coating on the particle surface. [Copyright &y& Elsevier]

Our country is supported by a very important solar site, it is almost sunny 10 months over the year with an average incidence of 966 W/m2 for one intermediate duration of 10 hours/days This encourages us to be directed towards an energy source available, free and ecological while taking into account the scientific solutions just fiIed to make the cost competitive, this while exploiting the configuration of the assembly or with the hybridization of the system. The characterization is the means par excellence which makes it possible to study the behavior of a photovolsaic module. The goal of the characterization is the determination of the principal parameters describing the electrical performances of the module. The object of this study is to have some results obtained during the characterization of the photovoltaic modules constituting the field installed at laboratory in University Center of Bechar. The experimental characteristics obtained were analyzed in order to determine the performances of the modules and their representative parameters (energetic efficiency, maximum power, fill factor…). These characteristics were relocated in the standard conditions in order to compare them with the characteristics data provided by the manufacturer. [ABSTRACT FROM AUTHOR]

Abstract: A proton-conducting solid electrolyte membrane based on polyvinyl phosphonic acid (PVPA) and 3-glycidoxypropyltrimethoxysilane was developed via the sol–gel process. The electrical conductivity of the organically-modified membrane obtained with optimum composition was 3.7×10−2 S·cm−1 at 353 K under 90% of relative humidity (RH), which was sufficient for its practical use as a solid electrolyte for fuel cells. In addition, a membrane based on polyphosphoric acid (PPA) and alkoxysilane was fabricated for comparison by employing polyethylene glycol dimethacrylate (PDM) as an additive. Though the PPA system (with PDM) exhibited similar electrical conductivity to the PVPA system, the latter had a superior mechanical strength and flexibility. Furthermore, the PVPA-based membrane with optimum composition was thermally stable up to ca. 473 K. The membrane exhibited electrical conductivity of 1.3×10−2 S·cm−1 at 398 K even under 30% of RH, which was similar to that of Nafion® at the same temperature under 100% of RH. [Copyright &y& Elsevier]

Copyright of Polimery is the property of Industrial Chemistry Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The phase behaviors of polyelectrolyte complexes formed from dilute solutions of poly(vinyl amine) (PVAm) and carboxymethyl cellulose (CMC) were determined as a function of overall composition and pH. The phase diagram included regions with soluble complexes, colloidal complexes, and macroscopic precipitates. Colloidal complexes were stable when either polymer was in sufficient excess to give electrosteric stabilization. The polymer mixing ratios giving complexes with an isoelectric point of 7 could be predicted from a simple model using the degree of ionization vs pH data for PVAm and CMC. The model failed at extreme pH values because not all added polymer was incorporated into the complexes. At pH 7, essentially all the added polymer was incorporated into the colloidal complex or precipitate, as long as the mixing ratio was within ±10% of charge stoichiometry. The interaction of PVAm and CMC at pH 7 was endothermic, supporting the generally accepted viewpoint that the interaction of oppositely charged polyelectrolytes is entropy-driven. Although the colloidal complexes had a broad particle size distribution, the average particle size was rather insensitive to mixing ratio. By contrast, complex size was sensitive to electrolyte concentration with no complex formation when the NaCl concentration was ≥2 M. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the pressure sensing properties of polyethylene (PE) and polyvinylidene fluoride (PVDF) polymer films were evaluated by integrating them with a wireless data acquisition system. Each device was connected to an integrated interface circuit, which includes a capacitance to frequency converter (C/F) and an internal voltage regulator to suppress supply voltage fluctuations on the transponder side. The system was tested under hydrostatic pressures ranging from 0 to 17kPa. Results show PE to be the more sensitive to pressure changes, indicating that it is useful for the accurate measurement of pressure over a small range. On the other hand PVDF devices could be used for measurement over a wider range and should be considered due to the low hysteresis and good repeatability displayed during testing. It is thought that this arrangement could form the basis of a cost-effective wireless monitoring system for the evaluation of environmental or physiological processes. [Copyright &y& Elsevier]

Abstract: We investigated the characteristics of heterogeneous layers composed of linear hydrolyzed polyvinylamine and branched polyethyleneimine adsorbed at silica/water interfaces. The studies also included heterogeneous layers where branched polyethyleneimine was replaced by polyethyleneimine modified by grafting with C12–C22 alkyl chains. Surface area exclusion chromatography was used to determine the interfacial relaxation and surface affinity of the polymer molecules within homogeneous layers. The relaxation of bare and grafted polyethyleneimine was found to be small and of equal extent but to develop at different rates. Comparatively, the relaxation of hydrolyzed polyvinylamine was faster and of greater extent. Within heterogeneous layers composed of polyvinylamine and bare or grafted polyethyleneimine, the relaxation of the different molecules was strongly increased as compared to that prevailing in homogeneous layers. The chromatographic method was then used to determine the mode of layer establishment. The polymer coating profiles on successive glass fiber filters were found to depend on the sequence of injection of the two polymers, due to the interfacial stability or instability of the initially established layer. It was shown that a previously established extremely thin layer of bare or grafted polyethyleneimine molecules strongly modified the adsorption profile of subsequently adsorbed polyvinylamine molecules. [Copyright &y& Elsevier]

A review of a many-year-long research on the method of preparation of polyvinylamine (PVAm) precursor suitable for implementation into industry has been presented. Just a few years ago BASF introduced the production of poly(N-vinylformamide) (PNVF) from easily polymerizing N-vinylformamide (NVF). PNVF hydrolysis in mild conditions leads to PVAm [equation (4)], which is now available on the market as well as NVF, and PNVF. The results of own research concerning NVF structure investigation were discussed. 13C NMR investigations let explain the higher reactivity of this monomer than of isomeric acrylamide. It was also found that PNVF hydrolysis in both acidic or basic environment was accompanied with ammonia evolution, not described up to now in the literature, what resulted in formation of some amount of γ-lactam units in PVAm [equation (5)]. The presence of NH2 groups in PVAm, bonded with backbone, creates various possibilities of their functionalization (Scheme A). Low solubility of PVAm in organic solvents is really a disadvantage but carrying out the polyreactions and then modification reactions in microemulsions let overcome it. Polymerization of methacrylamide in microemulsion with subsequent crosslinking with glutaric aldehyde [reaction (6), Fig. 5 and 6] is given as an example of this manner. NVF polymerization in microemulsion is a subject of another paper of the authors. [ABSTRACT FROM AUTHOR]

Abstract: Using alternating electrostatic layer-by-layer assembly of p-octasulfonato-calix[8]arene and polyvinylamine, multilayer assemblies were built up on porous polymer supports. The resulting composite membranes with ultrathin separation layer were studied on their permeability for various metal chloride salts in aqueous solution. The membranes were permeable for sodium chloride, but much less permeable for divalent metal chlorides such as magnesium and zinc chloride, the theoretical separation factors α (NaCl/MgCl2) and α (NaCl/ZnCl2) being 43 and 20. Rare earth metal chlorides LnCl3 with Ln being La, Ce, Pr and Sm and the related YCl3 were strongly rejected from the membrane, the theoretical separation factors α (NaCl/LaCl3) and α (NaCl/YCl3) being 138 and 160, for example. Possible origins for the selective ion transport are discussed in terms of Donnan rejection of the highly charged ions and complex formation of the rare earth metal ions with the p-sulfonato-calixarene units in the membrane. [Copyright &y& Elsevier]

Abstract: Solid-state compatibility and in vitro dissolution of direct-compressed sustained-release matrices of polyvinylacetate (PVAc) and polyvinylpyrrolidone (PVP) containing ibuprofen as a model drug were studied. Polyvinylalcohol (PVA) was used as an alternative water-soluble polymer to PVP. Differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) were used for characterizing solid-state polymer–polymer and drug–polymer interactions. The mechanical treatment for preparing physical mixtures of polyvinyl polymers and the drug (i.e. simple blending or stressed cogrinding) was shown not to affect the physical state of the drug and the polymers. With the drug–polymer mixtures the endothermic effect due to drug melting was always evident, but a considerable modification of the melting point of the drug in physical binary mixtures (drug:PVP) was observed, suggesting some interaction between the two. On the other hand, the lack of a significant shift of the melting endothermic peak of the drug in physical tertiary drug–polymer mixtures revealed no evidence of solid-state interaction between the drug and the present polymers. Sustained-release dissolution profiles were achieved from the direct-compressed matrices made from powder mixtures of the drug and PVAc combined with PVP, and the proportion of PVAc in the mixture clearly altered the drug release profiles in vitro. The drug release from the present matrix systems is controlled by both diffusion of the drug through the hydrate matrix and the erosion of the matrix itself. [Copyright &y& Elsevier]

Vinyl phenylsulfonylacetate (VPSA) was prepared by the reaction of vinyl chloroacetate with sodium benzenesulfinate in acetone in the presence of a phase-transfer catalyst. VPSA showed a high radical homopolymerizability similar to vinyl acetate in spite of the fact that VPSA carries a phenyl group. The polymerization of VPSA with 2,2′-azobisisobutyrate (MAIB) was kinetically investigated in acetone. The overall activation energy of the polymerization was 27.6 kcal/mol. The polymerization rate (Rp) at 50 °C was expressed by Rp=k[MAIB]0.67[VPSA]1.1. Poly(VPSA) showed exothermic (27 °C) and endothermic (57 °C) peaks in its DCS curve, corresponding to crystallization and melting. The tacticity of poly(VPSA) was estimated to be rr=29, mr=49, and mm=22. [Copyright &y& Elsevier]

A- Novel ways to synthesize poly(vinylamine)/silica hybrid materials rich in free amino moieties using vinylformamide (VFA) as the key monomer are reported. Such materials are accessible from poly(vinylamine) which is obtained from radically produced poly(vinylformamide) (PVFA) which was either immobilized on to silica surfaces from solution and converted into poly(vinylamine- co -vinylformamide) polymers (PVFA- co -PVAm) by acidic hydrolysis, or by acidic hydrolysis in solution with subsequent adsorption on to silica. We adsorbed control PVFA- co -PVAm samples of different molecular masses and co-polymer compositions from aqueous solutions on to inorganic surfaces such as silica or titania simply by pH control. Direct surface functionalization using the VFA monomers was possible by their radical graft co-polymerization with bifunctional monomers, for example 1,3-divinylimidazolid-2-one (BVU) or on silica particles which were pre-functionalized with vinyltriethoxysilane (VTS). The influence of the amino content and molar mass (4000, 40,000, and 400,000 g mol−1) of PVFA- co -PVAm on the degree of surface coverage, charging, and polarity was studied using X-ray photoelectron spectroscopy (XPS), potentiometric titrations, and electrokinetic measurements, and solvatochromic probes. It was shown that the amino content of the co-polymer has a significant influence on the amount of polymer adsorbed, the layer thickness, and surface polarity. Post-functionalization reactions with isocyanates or fullerene were used as a suitable method for enhancing the stability of the polyelectrolyte layer on the inorganic surface. They also open the way to producing multi-functional hybrid materials. The adsorption and post-functionalization of PVFA- co -PVAm samples on to gold-coated silicon wafer surfaces was used to build up laterally patterned surfaces for sensors and biological applications. [ABSTRACT FROM AUTHOR]

Fibril-shaped J-aggregates of pseudo-isocyanine dyes in ionic polymer poly(vinyl sulfate) are prepared and its optimization of the fabrication conditions have been successfully established. By the custom-made microscopic detection system, as well as imagings, local reflectance spectra and the polarization dependencies of the reflectance at the J-band(s) on the specific location of the fibrils with sub micrometer spatial resolution are observed. In the local reflectance spectra, an increase of the bandwidth roughly proportional to the increase of the local reflectance is observed. It is also found that the line shape of the reflection band becomes complicated at a higher reflectance and, from time to time, a dip-like structure appears at a slightly lower energy side of the so-called J-band. These properties can basically be interpreted by the model as a formation of Frenkel exciton-polariton in the fibrils or at least as being at the onset of polariton scheme from the simple exciton scheme. The results of the local fluorescence observation as well as those obtained in the fibrils formed in the ultra thin PVA polymer films are consistent with those of the model. From the local polarization dependencies, it is found that the direction of local transition dipoles can deviate from the long chain direction of the fibrils with a wide range of angles up to almost 90 degrees. The deviation appears at the polariton scheme range and also seems to be proportional to the magnitude of the local reflectance. Detailed results and discussions are presented. KEY WORDS J-Aggregates; PIC; PVS; PVA; Fibril-Shape; Exciton; Polariton; Microscope Imaging; Reflectance; Fluorescence. [ABSTRACT FROM AUTHOR]

The photochemical behavior of dichromated polyvinylalcohol (DCPVA) films was investigated to elucidate the first step of the reaction taking place in the photosensitive material. The work was completed for comparison by the investigation of DCPVA solutions.The difference in behavior appears in the ground state and in excited state. Processing a film modifies not only the spectral features of chromium(VI) but also the photochemical behavior. The photoredox process does not occur in basic aqueous DCPVA solution (pH=9) whereas it takes places in films prepared from that solution. The one electron photoreduction of Cr(VI) into Cr(V) is very efficient in both DCPVA films (acidic or basic) with Φ=0.65±0.05. The Φ values were calculated from the Cr(V) formation stable enough under the experimental conditions. All the results are in favor of the involvement of a complex between Cr(VI) and OH groups of polyvinylalcohol (PVA). ESR spectroscopy measurements upon irradiation further confirmed the formation and the stability of Cr(V) in PVA matrix. A very nice correlation appeared between Cr(V) behavior and the diffraction efficiency of holograms recorded in DCPVA as reported in the literature. [Copyright &y& Elsevier]

Focuses on a study which examined the rheological behavior of polyvinyl butyral (PVB) in the rubbery state. Rheological characterization of polyvinyl butyral; Constitutive equations for the stress-strain behavior.

The article reports on the price increase announced by Solutia Inc. for its polyvinyl butyral (PVB) products starting January 1, 2012.