Investigation of adsorbed polymer layers by flocculation of oppositely charged sols III. Effect of molecular mass of polymers

The stabilizing effect of water-soluble neutral polymers with different chemical structure and relative molecular mass on AgI sol has been studied. It was shown that the stabilizing effect of the polymers used is independent of the relative molecular mass of the polymer when equal amounts of the adsorbed polymers are compared with each other as stabilizers. The high stabilizing effect of polymers with high relative molecular mass is presumably due to the larger adsorbed amount.Among polyvinyl alcohol, polyvinyl pyrrolidone and methylcellulose, polyvinyl pyrrolidone exhibits the smallest stabilizing layer thickness at equal adsorbed amounts. According to our earlier results this is due to the fact that the polyvinyl pyrrolidone shows the strongest affinity for AgI surfaces, forming short loops or tails.     

Novel Rare Earth–Polyvinyl Pyridine Complex Functionalized Hybrid Silica Microspheres: Molecular Assembly and Photophysical Property

The functional silica microspheres are derived from the three different silane crosslinking reagents, and then the polyvinyl pyridine-based rare earth hybrids are synthesized through free radical copolymerization of rare earth–vinyl pyridine complex monomer with these functionalized silica microspheres (RE = Eu, Tb). The obtained hybrids are characterized by Fourier transform infrared, X-ray diffraction, Scanning electronic microscope and photoluminescence spectra. The intramolecular energy transfer process between rare earth ions and polymer polyvinyl pyrrolidone matrices took place within these polymer-based hybrids and especially the quantum efficiency of europium hybrids are determined, suggesting that the hybrid material systems derived from different functional silica microspheres present different luminescence efficiencies.     

Bromine Complexes of Polyvinylpyrrolidone Supports: A Mild Reagent for the Transformation of α‐Oxoketene Dithioacetals to β‐Oxothiolesters

When α‐oxoketene dithioacetals 1a–n were treated with the bromine complex of a copolymer of 1‐vinyl‐2‐pyrrolidone and 4‐vinylpyridine, the corresponding thiolcarboxylates 2a–n were formed in excellent yields. The reaction also works with other 1‐vinyl‐2‐pyrrolidone‐derived polymers as well as commercially available polyvinylpyrrolidone–bromine complexes. The method is suitable for preparing aliphatic, aromatic, and γ,δ‐unsaturated β‐oxothiolcarboxylates.     

Oxoaminium salts as initiators for cationic polymerization of vinyl monomers

Oxoaminium salt ( 1 ), derived from 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO, 2 ) by one-electron oxidation, could be an initiator for cationic polymerization of vinyl monomers such as isobutyl vinyl ether (IBVE), 2,3-dihydrofuran, p-methoxystyrene, N-vinyl pyrrolidone, etc., to give the corresponding polymers, when 1 had a low nucleophilic counter anion. Formation of the adducts of 1 and IBVE as well as ¹H-NMR and IR data suggested the formation of polymers containing N? O? C structure as the polymer head group. In the polymerization of IBVE, the effects of solvent and concentration of 1 were little observed, however the polymerization rate was dependent on temperature. Furthermore, the thermal reaction of the polymers obtained, which were regarded as prepolymers for block copolymerization and polymeric initiators for radical polymerization, was studied. For example, poly(2-benzylidene-1,3-dioxane) obtained by the polymerization of 2-benzylidene-1,3-dioxane with oxoaminium hexafluoroantimonate ( 1, X = SbF₆) was employed as an initiator for radical polymerization of MMA to give its block copolymer with PMMA. © 1993 John Wiley & Sons, Inc.     

Effect of compatibility on the structure of the microporous membrane prepared by selective dissolution of chitosan/synthetic polymer blend membrane

The method to prepare microporous chitosan membrane by selective dissolution of its blend was evaluated. Two synthetic polymers, e.g. polyvinyl pyrrolidone (PVP) and polyethylene glycol (PEG), were chosen to be the counterpart polymers. Results of Fourier transform infrared (FTIR) characterization, differential scanning calorimeter (DSC) analysis, wide angle X-ray diffraction (WAXD) measurements showed that there are special interactions between chitosan and the counterpart polymers. The pore structure induced by this method is controlled by the compatibility of the chitosan and the counterpart polymers. No pore structure was induced in the case of chitosan/polyvinyl pyrrolidone because of their molecule level miscibility and strong interaction. Highly porous structure was induced in the case of chitosan/polyethylene glycol because of their poor compatibility and multiphase structure.     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

In situ polymerization and morphology of polypyrrole obtained in water‐soluble polymer templates

Several water‐soluble polymers were used as templates for the in situ polymerization of pyrrole to determine their effect on the generation of nanosized polypyrrole (PPy) particles. The polymers used include: polyvinyl alcohol (PVA), polyethylene oxide (PEO), poly(vinyl butyral), polystyrene sulfonic acid, poly(ethylene‐alt‐maleic anhydride) (PEMA), poly(octadecene‐alt‐maleic anhydride), poly(N‐vinyl pyrrolidone), poly(vinyl butyral‐co‐vinyl alcohol‐co‐vinyl acetate), poly(N‐isopropyl acrylamide), poly(ethylene oxide‐block‐propylene oxide), hydroxypropyl methyl cellulose, and guar gum. The oxidative polymerization of pyrrole was carried out with FeCl₃ as an oxidant. The morphology of PPy particles obtained after drying the resulting aqueous dispersions was examined by optical microscopy, and selected samples were further analyzed via atomic force microscopy. Among the template polymers, PVA was the most efficient in generating stable dispersions of PPy nanospheres in water, followed by PEO and PEMA. The average size of PPy nanospheres was in the range of 160 nm and found to depend on the molecular weight and concentration of PVA. Model reactions and kinetics of the polymerization reaction of pyrrole in PVA were carried out by hydrogen ¹H NMR spectroscopy using ammonium persulfate as an oxidant. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Organometallic polymers. IV. Organometallic modifications of halogen-containing polymers

The synthesis of ferrocene-containing polymers by chemical modification of chlorinated polyethylenes, polyvinyl chloride (PVC), and other halogenated polymers, under Friedel-Crafts conditions, is described. The effect of reaction conditions on the structure and composition of the products obtained with various substrates was investigated. Soluble polymers of up to 62% ferrocene content were obtained. In most cases, substitution was accompanied by dehydrohalogenation. The ferrocene-to-vinylene ratio was higher in the reaction products of chlorinated polyethylenes than in those of PVC.     

Head-to-Head Polymers

Head-to-head polymers of α-olef ins, vinyl and acrylic monomers synthesized by indirect methods have shown similarities and differences in some of their behavior when compared to their counterparts of the common head to tail polymers. Head-to-head polyole-fins, such as polystyrene or polypropylene, were prepared by 1,4-polymerization of the corresponding 2,3-disubstituted butadienes-1,3 followed by hydrogenation of the remaining double bonds, polyacrylates by alternating copolymerization of ethylene and maleic anhydride, followed by esterification of the polymer. Head-to-head polyacrylates were reduced to poly(allyl alcohols) which were then acrylated to the acetates and benzoates. Head-to-head polyvinyl halides) were obtained from 1,4-polybutadiene by chlorination or bromination. The head-to-head polymers were characterized by spectroscopic analysis, some molecular weight characterization was done, and their thermal behavior was studied. The blending behavior with the corresponding head-to-tail polymers was studied in some cases; in others (head-to-head polystyrene), the blending with other polymers was investigated and the codegradation of the polymers was evaluated.     

Polymere für Frisuren: Haarsprays,Festiger & Co.

Polymers play an important role in hair cosmetics due to their ability to change the properties of the hair. In order to tailor the properties such as fixative power, wash‐out and elasticity, polymers are generated by smart choice of monomer composition and process technology. Up to the seventies, polyvinylpyrrolidone and its copolymers were dominant. In the seventies, copolymers of vinyl acetate with further monomers followed and copolymers of methyl vinylethers with maleic acid half esters. Polyquaternium compounds were developed (copolymers of vinyl pyrrolidone with quaternized vinyl imidazole or dimethylaminomethyl methacrylate)to ease the combing of hair. In the seventies and eighties, copolymers of acrylate monomers and their esters or alkylacrylamides were supplied. The latest developments aim for polymers with covalently bound silicon compounds in order to ease the demanding formulation work, or for polymers which allow a formulation with water as substitute for alcohol as solvent.     

The polymerization of acrylic acid in the presence of copolymers containing interacting and non-interacting groups

There has been a kinetic examination of the polymerization of acrylic acid in dilute aqueous solution in the presence of copolymers of vinyl pyrrolidone with acrylamide or styrene. In general, the characteristics of the polymerizations are very similar to those found in the presence of polyvinyl pyrrolidone homopolymer, but the definite differences, taken in conjunction with gravimetric data on the polymer complexes, can be explained by the fact that acrylamide is hydrophilic while styrene is hydrophobic. The use of the copolymers has permitted an assessment of the effect of dilution of monomer adsorbed on the interacting polymer.     

Synthesis of polyanilines with polyaromatic substituents

Polyanilines containing diphenyl, terphenyl, anthracene, carbazole, and 4-n-hexylbenzene have been prepared through the interaction of polyanilines in the form of the emeraldine base with corresponding sodium salts of aromatic derivatives of vinyl ketones. The polymers have been characterized by thermogravimetry, IR spectroscopy, and ¹H NMR measurements. The emission characteristics of the polymers in N-methyl-2-pyrrolidone solution have been studied.     

Energy and acid-base characteristics of the surfaces of polymeric modifiers for filled cellulose nitrate composites

The energy and acid-base characteristics of the surface of butadiene-nitrile (SKN-18, SKN-26, SKN-40) and urethane (SKU-8A, SKU-8TB) rubbers, and also of polyvinyl nitrate and polyvinyl butyral were determined. Butadiene-nitrile rubbers are characterized by the highest, and vinyl polymers, by the lowest free surface energy. The free surface energy of urethane rubbers has intermediate values. The results obtained show that the surface energy of the polymers is determined both by the chemical nature of functional groups located directly in the surface layer and by the macromolecular packing density. The surface acidity increases in the order polyvinyl butyral < polyvinyl nitrate < SKU < SKN. The nature of the surface of the polymers under consideration is determined by prevalence of certain acid-base sites of adhesion interaction as a result of conformational turns of macromolecular chain segments.     

Quality testing of human albumin by capillary electrophoresis using thermally cross‐linked poly(vinyl pyrrolidone)‐coated fused‐silica capillary

To detect the quality of medicinal human albumin by capillary electrophoresis, we produced a fused‐silica capillary coated with thermally cross‐linked poly(vinyl pyrrolidone) to prohibit protein adsorption. This type of capillary was easily obtained by injecting an aqueous poly(vinyl pyrrolidone) solution into a fused‐silica capillary and thermally annealing it at 200°C. Notably, stable and low electro‐osmotic flow was obtained in the poly(vinyl pyrrolidone)‐coated capillary at pH 2.20–9.00, and the separation of a mixture of four basic proteins indicated that the poly(vinyl pyrrolidone)‐coated capillary exhibits excellent repeatability and separation efficiency; moreover, the separation of these four basic proteins could even be achieved at pH 7.00. The protein recovery percentage of human serum albumin in a single‐protein solution and a mixed blood proteins solution was determined to be 97.03 and 95.40% in the poly(vinyl pyrrolidone)_50–3 (representing the concentration of the capillary‐injected poly(vinyl pyrrolidone) aqueous solution, 50 mg/mL, and thermal annealing time, 3 h) capillary, respectively. Based on these results, we used the poly(vinyl pyrrolidone)_50–3‐coated capillary to quantify the protein content of human albumin, and the results obtained from run to run, day to day and capillary to capillary demonstrated that the coated capillary could be used for quality testing commercially available human albumin.     

“Living” free radical graft copolymers I: Preparation and properties

Polymers substituted with thio groups are useful for the photochemical synthesis of graft copolymers. Such copolymers have been prepared by the initial conversion of backbone polymers containing chlorinated substituents into polymers containing diethyldithiocarbamate (TC), isopropyl xanthate (IX) or mercaptobenzothiazole (BT) functionality. The photochemical reaction of monomers with these products produced graft copolymers. A variety of halogenated polymers were investigated as starting materials for these syntheses, including poly(vinyl chloride), chlorinated polyvinyl chloride), chlorinated polyethylene, chlorobutyl rubber and neoprene. Characteristics of the grafting reactions, including “pseudo-living” behavior and tandem grafting aspects, were investigated. Glass transitions of the grafted polymers were found to vary uniformly with composition for most of the grafted products.     

Synthesis of N-substituted polyethylenimines with polarizable side chain pendent groups

Two new N-substituted polyethylenimines containing carbazole and acridone groups on the side chains were prepared. The polymers were obtained by cationic ring opening polymerization of the corresponding 2-oxazoline monomers. The carbazole containing oxazoline was low melting and could be polymerized in bulk; however the acridone containing monomer had a high melting point and solution polymerization had to be used. This paper describes the synthetic procedures used to obtain these polymers.     

Polydimethylsiloxane–vinyl block polymers. II. The synthesis and characterization of block polymers by the thermolysis of polydimethylsiloxane macroinitiators containing bis(silyl pinacolate) groups

The thermolysis of polydimethylsiloxanes containing thermally labile bis(silyl pinacolate) groups in the backbone in the presence of various vinyl monomers leads to the direct synthesis of block polymers. Depending on the monomer chosen, simple triblock or multisequence block polymers can be readily prepared. Analysis of the products of the block polymerizations using various styrenic-type monomers shows that only block polymers are obtained, i.e., no homo-polymers are formed. These block polymers display evidence of phase separation such as intense iridescence and solvent-dependent mechanical properties. The mechanical properties of these block polymers have been measured and found to be highly composition dependent. Depending on the block length and the relative portions of the hard (vinyl) and soft (polydimethylsiloxane) blocks, one can produce either thermoplastic elastomers or rubber-modified thermoplastics.     

Binding of hexadecylammonium surfactants to water-soluble neutral polymers

The binding of hexadecyltrimethylammonium bromide and hexadecyldimethyl-2-hydroxyethylammonium bromide to neutral polymers was measured by a potentiometric titration method using surfactant selective electrodes. Binding to poly(vinyl alcohol) was slightly cooperative, while that to poly(ethylene oxide) lacked the co-operativity. Poly(vinyl pyrrolidone) did not bind them at all. Binding affinity as estimated by a distribution coefficient of the cationic surfactants between the bulk and polymer phases is about 2 orders of magnitude smaller than that of anionic sodium dodecyl sulfate. The heat of binding was estimated from the temperature dependence of the distribution coefficient and found to be endothermic. It is imagined that the cationic surfactants are simply partitioned between the aqueous bulk phase and the polymer coil phase which is regarded as aqueous organic mixed solvent.     

Thermodynamic Study of Poly(vinyl pyrrolidone) in Water/Dimethyl Sulfoxide Solutions by Viscometry

In this work, the intrinsic viscosities of poly(vinyl pyrrolidone) with a molar mass of 58?kg?mol^?1 were measured in water?Cdimethyl sulfoxide solutions at temperatures from (298.15 to 318.15)?K. The expansion factors of the polymer chains were calculated from the intrinsic viscosity data. The thermodynamic parameters (entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer?Csolvent interaction parameter and second osmotic virial coefficient) were derived by the temperature dependence of the polymer chain expansion factor. The thermodynamic parameters indicate that mixtures of water/dimethyl sulfoxide become poorer solvents for poly(vinyl pyrrolidone) as the temperature is increased. Also, the thermodynamic parameters indicate that water/dimethyl sulfoxide mixtures become better solvents for poly(vinyl pyrrolidone) by increasing the volume fractions of dimethyl sulfoxide.     

Ultrasonic Modification of Polymers. II. Degradation of Polystyrene,Substituted Polystyrene,and Poly(n-vinyl Carbazole) in the Presence of Flexible Chain Polymers

Abstract

Ultrasonic (20 kHz, 70 W) solution degradations of polystyrene, substituted polystyrenes, and poly(n-vinyl carbazole) have been carried in toluene and tetrahydrofuran at 27 and -20°C in the presence of flexible chain polymers. Polystyrene formed block copolymers at 27°C with stiff-chain polymer PVCz; however, in the presence of flexible chain polymers, e.g., poly(vinyl methyl ketone) or poly(vinyl methyl ether), there were no block copolymers formed. Poly(n-vinyl carbazole) does not seem to form any block copolymers at 27°C with flexible chain polymers, e.g., poly(octadecyl methacrylate) and poly(ethyl methacrylate). Poly(p-chlorostyrene) and poly(p-methoxystyrene) also do not form block copolymers at 27°C with poly(octadecyl methacrylate) but do so with poly(hexadecyl methacrylate). It is quite possible that these may only be blends of two homopolymers. Poly(octa-decyl methacrylate) does yield a block copolymer when sonicated at -15°C with poly(p-isopropyl α-methylstyrene).