Molecular and Conformational Properties of Dendronized Polymethacrylate in Organic Solvent

The conformational and dynamo-optical properties of a homologous series of polymethacrylate modified by first-generation Fréchet-type dendrons in the molecular mass range of 70–8800 kDa in organic solvents were studied by viscometry, isothermal diffusion, dynamic light scattering, and flow birefringence. The Mark-Kuhn-Houwink equations for this dendronized polymer in toluene and chloroform together with hydrodynamic diameter and Kuhn segment length in toluene are defined as well as the value of intrinsic anisotropy of polarizability for the monomer unit.     

Properties of vinylpyrrolidone-tert-butylphenyl methacrylate copolymers in solution

Copolymers of vinylpyrrolidone-p-tert-butylphenyl methacrylate (VP-MBPh) of several compositions were prepared by polymerization in benzene at 50°C using α′α′-azobisisobutyronitrile as initiator. Three of the copolymers were fractionated. Number-average molecular weights of fractionated samples were determined by osmotic pressure in benzene or 2-propanol. Kuhn–Mark–Houwink relations were established in benzene, chloroform, and 2-propanol. From the relation between M _n and the intrinsic viscosity (η), it appears that these random copolymers behave as predicted by the theory for flexible polymers. Abnormal viscometric behavior shown by one of the copolymers in nitromethane at 29°C (the theta temperature) is discussed. The Stockmayer–Fixman semiempirical method was used for estimating unperturbed dimensions from viscosity data obtained in chloroform, a good common solvent. Values of the viscosity parameter K_θ increase with the content of p-tert-butylphenyl methacrylate. In general, experimental K_θ values are higher than those calculated for the homopolymers. Excluded-volume parameters are estimated and discussed in relation to repulsive interactions between unlike monomer units.     

Carbazole-functionalized polyfluorenes: synthesis and conformational properties in chloroform solution and β-phase formation in copolyfluorene films

Novel copolyfluorenes (CPFs) containing 2.5 or 10 mol% of carbazole-2,7-diyl (2,7-Cz) or carbazole-3,6-diyl (3,6-Cz) derivatives in the backbone have been synthesized by means of palladium-catalyzed Suzuki polymerization under microwave irradiation. The structure of the CPF polymers was also modified by insertion of additional 2-ethylhexyl or carbazole, diaryloxadiazole, or triphenylamine units via 3,6-Cz or 2,7-Cz comonomer units in the side chains of polymers. The self-organization of molecules in chloroform solutions was investigated using light scattering and within a wide concentration interval. Analysis of the behavior of the CPFs showed that the synthesized copolymers have an increased equilibrium rigidity of molecules with a Kuhn segment length A = (10–15) nm. The A value decreases with the introduction of Cz-units into the macromolecule in the meta-position. It is shown that chemical structure of the CPFs and thermal treatment in the temperature range 60–150 °C have a dominant effect on the optoelectronic properties as well as on microstructures of their films.     

Heat-Resistant Polyfunctional Materials for Microelectronics: Hydrodynamic,Optical, and Conformational Properties of Si-Containing Poly(<Emphasis Type="Italic">ortho</Emphasis>-Hydroxy Amide)

Polycondensation of a mixture of diamines, 3,3'-dihydroxy-4,4'-diaminodiphenylmethane and bis-(3-aminopropyl)dimethylsiloxane taken in a 3: 2 molar ratio, with isophthaloyl chloride was used to synthesize a silicon-containing poly(ortho-hydroxyamide) POA-Si exhibiting an increased adhesion to such substrates as Si, SiO₂, quartz, glass, and glass-ceramics. The polymer was separated by the fractional precipitation method into seven fractions and its polydispersity was evaluated. The degree of intramolecular orientation ordering (Kuhn segment) was determined and Mark–Kuhn–Houwink equations were derived, which can be used to determine the molecular masses of the newly synthesized samples.     

Transport parameters of glassy polymers: Effect of occupied and accessible volumes

The occupied and accessible volumes have been calculated for 32 polyimides of various structures. The calculation data have been compared with the experimentally measured transport parameters for one polymer-various gases and one gas-various polymers systems. The correlation coefficients have been estimated as 90–98%. The transport parameters plotted as a function of the Kuhn segment are described by curves with maxima. The best transport characteristics are exhibited by polymers with Kuhn segment lengths of 60–80 Å.     

Intrinsic viscosities of polymers in mixed solvents

The intrinsic viscosity of a polymer in a solvent mixture is related to the excess free energy of the solvents. Intrinsic viscosities at different temperatures are obtained for poly-2-vinylpyridine–chloroform–ethyl alcohol, poly(methyl methacrylate)–chloroform–ethyl alcohol, polystyrene–cyclohexane–benzene, polystyrene–dioxane–chloroform, and polystyrene–cyclohexane–ethanol. Qualitative, but not quantitative, agreement is found between theory and experiment.     

Comment on the dynamic bead size and Kuhn segment length in polymers: Example of polystyrene

Discrepancies between the length of a traditionally defined Kuhn segment length (l_k) and a bead size estimated from experimental data have been reported in a number of articles. In this work we emphasize that the traditional definition of the Kuhn segment is an oversimplification and the characteristic ratio, C_∞, is not the only parameter that defines a bead size. We show that the dynamic bead size in polystyrene (PS) might be as large as ～50 monomers, whereas the traditionally defined Kuhn segment is ～8–10 monomers. It is shown that with 50 monomers (M ～ 5000) as a size of the dynamic bead, one can explain many inconsistencies in the interpretation of compliance and mechanical relaxation data known for low‐molecular weight PS. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3505–3511, 2004     

Protonated member of poly(diallylammonium) family: Hydrodynamic and conformational properties

Secondary polyamine in protonated salt form – poly(diallylammonium trifluoro-acetate) is characterized as representative of polymer series based on N,N-diallyl-ammonium. Its hydrodynamic behavior in 1 M NaCl has been compared with the other series members – quaternary poly(diallyldimethylammonium chloride) and tertiary poly(diallylmethylammonium trifluoroacetate). It was shown that these polymers belong to semirigid class whose Kuhn segment length ～4?nm just slightly depends on chemical structure at high ionic strength. As specific for secondary polyamine, the sensitivity to proton equilibrium in solution and counter ion type was detected resulting in great difference of its Mark–Kuhn–Houwink equations from the quaternary analogue at the same conditions.     

Entropy-Driven Cooperativity in the Guest Binding of an Octaphosphonate Bis-cavitand

Uncommon entropy-driven cooperativity is reported in the guest binding of an octaphosphonate bis-cavitand. Isothermal titration calorimetry determined the thermodynamic parameters for the 1:2 host–guest binding of bis-cavitands with ammonium guests in methanol, ethanol, 2-propanol, and chloroform. Chloroform drove uncommon entropy-driven cooperative binding, whereas the alcohols resulted in enthalpy-driven noncooperative binding. ¹H NMR studies revealed that each cavity contained six water molecules in chloroform, which were liberated on guest binding. The enthalpy–entropy compensation relationship produced a large positive intrinsic entropy in chloroform, which implies that water desolvation causes a considerable entropic gain by paying an enthalpic penalty due to breaking the hydrogen-bonding networks of the water clusters.     

Ring-opening polymerization of 1,5-dioxepan-2-one initiated by a cyclic tin–alkoxide initiator in different solvents

Ring-opening polymerization of 1,5-dioxepan-2-one initiated by 1,1,6,6-tetra-n-butyl-1,6-distanna-2,5,7,10-tetraoxacyclodecane was carried out in chloroform, dichloromethane, or 1,2-dichloroethane. Effects of reaction temperature, solvent, and monomer-to-initiator ratio were investigated. Polymerization kinetics showed a first-order dependence on the monomer for polymerization in chloroform and dichloromethane at 40°C. The kinetic order with respect to the initiator were a first order when dichloromethane was used as the solvent, the order in initiator changed, depending on the initiator concentration when chloroform was used. A maximum in molecular weight was observed at 40°C when chloroform was used as the solvent. The change of solvent did not markedly alter the polymerization rate or the molecular weight of the polymers prepared, as expected from the coordination insertion mechanism. Depolymerization of the polymers formed was observed when the reaction was allowed to continue after complete monomer conversion in chloroform as reaction medium at 40°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3407–3417, 1999     

Hydrodynamic properties and conformation of poly(3‐hexylthiophene) in dilute solutions

Conducting polymers demonstrate low solubility in organic solvents. Introducing aliphatic substituents into polymer chains improves their solubility, but may also lead to changes in conformational characteristics of macromolecules. In the present work, the studies of hydrodynamic properties and conformational characteristics of comb‐shaped poly(3‐hexylthiophene) with aliphatic side substituents were carried out in chloroform solutions. Conformational analysis of the studied macromolecules was performed for the first time using homologous series with a wide range of molecular weights of the polymers in dilute solutions. The hydrodynamic properties of these macromolecules were interpreted using the worm‐like spherocylinder model and the straight spherocylinder model. The projection of the monomer unit in the direction of the main polymer chain λ = 0.37 nm was determined experimentally. The following parameters of poly(3‐hexylthiophene) were characterized and quantified: equilibrium rigidity (Kuhn segment length) А = 6.7 nm and hydrodynamic diameter of a polymer chain d = 0.6 nm. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 875–883     

Improved in‐solution trypsin digestion method for methanol–chloroform precipitated cellular proteomics sample

Methanol–chloroform based protein precipitation is an essential step in many liquid chromatography–tandem mass spectrometry‐based cellular proteomics applications. However, re‐solubilization of the total protein precipitate is difficult using regular in‐solution digestion protocol. Sodium deoxycholate is reported as an efficient surfactant for re‐solubilization of membrane fractions. In this study, we demonstrated an application combining methanol–chloroform based protein precipitations and deoxycholic acid assisted re‐solubilization of pellets to evaluate the improvement of protein identifications in mass spectrometry‐based bottom‐up proteomics. We evaluated the modified method using an equal amount of Raw 264.7 mouse macrophage cell lysate. Detailed in‐solution trypsin digestion studies were presented on methanol–chloroform precipitated samples with or without deoxycholic acid treatments and compared with popular sample digestion methods. A mass spectrometric analysis confirmed an 82% increase in protein identification in deoxycholic acid‐treated samples compared to other established methods. Furthermore, liquid chromatography–tandem mass spectrometry analysis of an equal amount of proteins from methanol–chloroform precipitated, and methanol–chloroform/deoxycholic acid‐treated macrophage cell lysate showed a 14% increase and 27% unique protein identifications. We believe this improved digestion method could be a complementary or alternative method for mammalian cell sample preparations where sodium dodecyl sulfate based lysis buffer is frequently used.     

Synthesis and properties of conjugated fluoroalkyl ether-substituted polythiophenes prepared in organic solvent and supercritical carbon dioxide

A number of new fluoroalkyl ether-containing polythiophenes are synthesized via oxidative polymerization in supercritical CO₂ (scCO₂) and chloroform. In both cases, high-molecular-mass polymers with high yields are prepared. The properties of the polymers synthesized in scCO₂, such as molecular mass, polydispersity, conjugation, and UV absorption, are similar to the properties of the polymers obtained in chloroform. All poly(fluoroalkyl ether thiophenes) show solubility in DMF, toluene, THF, chloroform, and acetone. The glass-transition temperatures of the polymers are in the range 58–82°C, and the temperatures corresponding to 10% loss in their weight are in the ranges 248–294 and 260–303°C for poly(fluoroalkyl ether thiophenes) synthesized in scCO₂ and chloroform, respectively. All polymers fluoresce in the blue region with emission maxima at 506 to 526 nm. Because of the unique combination of fluoroalkyl and carbonyl groups, poly(fluoroalkyl ether thiophenes) feature good solubility in scCO₂, which is a promising alternative solvent for the oxidative polymerization of fluoroalkyl ether thiophenes.     

Oleophilic ion-exchange resins. IV. Swelling of quaternary ammonium polymers in mixed solvents

The swelling characteristics of an oleophilic anion-exchange resin in methanol–benzene and ethanol–chloroform mixed solvent systems were compared with those of a conventional anion-exchange resin. The oleophilic resin was prepared by amination of chloromethylated polystyrene 1% DVB with N,N-dimethyldodecylamine. It showed a large shift of the swelling peak from polar to less polar solution compositions in both methanol–benzene and ethanol–chloroform systems as compared with the swelling of conventional resins. Total solvent uptake and solvent distribution between resin and solvent phases were also determined. The less polar solvent (benzene or chloroform) was sorbed preferentially by the oleophilic resin over a wide range of composition, while preference for the more polar solvent (methanol or ethanol) by the conventional resin was shown over the entire composition of the mixed solvent systems. The Newman-Krigbaum treatment of mixed solvents was applied to swelling data on the ethanol–chloroform–oleophilic resin system, where the volume of the gel network plus the solvent imbibed was relatively constant over the entire range of composition. The result suggests a strong similarity of the liquid–liquid interaction terms in this gel phase compared with those in the pure binary liquid phase.     

Synthesis and characterization of polyaniline–zirconium dioxide and polyaniline–cerium dioxide composites with enhanced photocatalytic degradation of rhodamine B dye

For the first time, chloroform and 2-butanol were used as solvent systems for the preparation of ZrO₂–PANI and CeO₂–PANI composites. Solubility of the synthesized composites was studied in chloroform, N-methyl-2-pyrrolidinone (NMP), and in mixture of toluene?+?2-propanol (2:1). XRD and cyclic voltammetry data showed that the ZrO₂–PANI and CeO₂–PANI composites possess both crystalline and amorphous domains indicating some sort of conductivity. TGA results showed that ZrO₂–PANI composite have a better thermal stability than pure PANI; however, CeO₂–PANI composite has lower thermal stability than pure PANI. The conjugated unsaturated structure of PANI is responsible for the enhanced photocatalytic properties of ZrO₂–PANI and CeO₂–PANI. Photocatalytic results showed that, at photolysis time of 60 min, rhodamine B (RhB) dye was degraded up to 34 and 35% by ZrO₂–PANI and CeO₂–PANI, respectively. The degradation products of RhB were quantified by LC–MS and GC–MS, and accordingly, a detailed pathway was proposed.     

Effect of chloroform on the structure and gas-separation properties of poly(ether imides)

The FTIR spectra of poly(ether imide) films prepared from their chloroform solutions were recorded in a wide temperature interval. The cast films were shown to contain residual solvent. This residual solvent existed in films as unbound chloroform that may be removed by heating to 60–70°C and as bound chloroform that is involved in complex formation with polymers and may be removed by heating at temperatures close to their glass transition temperatures (180°C). Quantum-chemical calculations were performed for structures that model fragments and monomer units of poly(ether imides), as well as their complexes with chloroform. Chloroform was shown to be capable of preferential binding with an oxygen atom in a Ph-O-Ph′ fragment via hydrogen bonds. In this case, the conformational set of poly(ether imide) chains is changed. The above evidence is invoked to explain changes in transport characteristics with time for poly(ether imide) films cast from chloroform solutions.     

Preparation and properties of fluorine-containing polyarylates from tetrafluoroisophthaloyl chloride and bisphenols

Fluorine-containing polyarylates having inherent viscosities of 0.2–0.8 dL/g were prepared from tetrafluoroisophthaloyl chloride and various bisphenols by low temperature solution polycondensation in chloroform with triethylamine or by two-phase polycondensation in a dichloromethane-water or nitrobenzene-water system with benzyltriethylammonium chloride as the phase transfer catalyst. These polyarylates were amorphous and were readily soluble in various solvents, including chloroform and N-methyl-2-pyrrolidone. The glass transition temperature of the polymer derived from 2,2-bis(4-hydroxyphenyl) propane was 150°C. These polyarylates started to lose weight around 350°C in an air or nitrogen atmosphere.     

Separation of nitrophenols. Equilibriums in bi- and tri-phasic systems

The paper presents experimental data obtained in the study of liquid–liquid partition equilibriums in biphasic system in order to optimize the process of transport through bulk liquid membranes (triphasic partition systems). The partition equilibriums of some nitrophenols using chloroform as extraction solvent and membranary solvent, respectively, were studied. The influence of the pH on the partition equilibriums was investigated. The repartition constants and the pK_a values of the studied nitrophenols were calculated. Nitrophenols were transferred in triphasic system from a feed phase with pH 2, through a chloroform liquid membrane, into a receiving phase with pH 12, with efficiencies over 90%.     

Self-Diffusion and Heteroassociation in an Acetone–Chloroform Mixture at 298 K

The self-diffusion coefficients of acetone and chloroform in a binary acetone–chloroform mixture at 298 K are determined via pulsed field gradient NMR spectroscopy. It is estimated that the hydrodynamic radii of the mixture’s components, calculated using the Stokes–Einstein equation, grow as the concentrations of the components fall. It is shown that such behavior of hydrodynamic radii is due to acetone–chloroform heteroassociation. The hydrodynamic radii of monomers and heteroassociates in a 1: 1 ratio are determined along with the constant of heteroassociation, using the proposed model of an associated solution.     

Solution properties of cellulose triacetate. I. Fractional precipitation

Using petroleum ether as a precipitant and chloroform–acetone mixture as solvent, six fractions of cellulose triacetate were obtained by fractional precipitation. The molecular weight of each fraction was obtained from osmotic pressure measurements carried out on chloroform solutions. It was shown that virtual nonfractionability of cellulose triacetate with regard to molecular weight occurred in this system. This behavior was also observed in attempts to fractionate it from tetrachloroethane or acetic acid solutions. These results are explained by the hypothesis that specific polymer–solvent interaction takes place due to hydrogen bonding.