Rheological properties of poly(1-trimethylsilyl-1-propyne) solutions

The phase state and rheological properties of poly(1-trimethylsilyl-1-propyne) solutions in toluene and cyclohexane are studied. Samples of poly(1-trimethylsilyl-1-propyne) have the same backbone structure (cis-trans configuration ratio) but different molecular masses. Phase diagrams of these systems are derived via optical interferometry. It is found that they have an upper critical mixing temperature (UCMT) whose value exceeds the boiling points of the individual solvents. The two solvents exhibit limited solubility with respect to the studied polymer, and this parameter decreases with an increase in the molecular mass of the polymer. In the transition from dilute to concentrated solutions, the pattern of the rheological behavior changes from Newtonian to pseudoplastic. The concentration dependences of the zero-shear-rate viscosity of the solutions are typical for flexible-chain polymers. The viscous behavior of the poly(1-trimethylsilyl-1-propyne)-solvent system can be described through a single generalized viscosity-concentration relationship if dimensionless reduced values that take into account the contribution of the molecular mass, the nature of the solvent, and the pattern of intermolecular interactions in the solutions are used as the argument and the function.     

Electrooptical and Conformational Properties of Poly(1-Trimethylsilyl-1-Propynes) with Different Chain Microstructures

The methods of the Kerr effect and solution hydrodynamics were applied to study the electrooptical and hydrodynamic properties of samples of disubstituted polyacetylenes, poly(1-trimethylsilyl-1-propynes), prepared by polymerization of 1-trimethylsilyl-1-propyne with NbCl₅ and TaCl₅/BuLi as catalysts. The experimental electrooptical characteristics of polymers were compared with those calculated by PM3 semiempirical quantum-chemical method.     

Chemical modification of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) using highly reactive metallating systems

Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are metallated using normal and secondary butyllithium chelate complexes with tetramethylethylenediamine and superbases based on complexes of normal and secondary butyllithium with potassium tert-pentoxide as metallating agents. Optimal conditions ensuring metallation of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) with a high yield without degradation of macrochains are determined. Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are functionalized via reactions of metallated polymers with CO₂, trimethylsilyl chlorosulfone, diethyl disulfide, and ethylene oxide. COOH, SO₃H, OH, and thioester groups are introduced into poly(vinyltrimethylsilane), and SO₃H and COOH groups are incorporated into poly(1-trimethylsilyl-1-propyne). Upon introduction of carboxyl groups into poly(vinyltrimethylsilane), its hydrophilicity and permselectivity with respect to H₂O/N₂, H₂O/H₂, and H₂O/CH₄ pairs increase. The introduction of SO₃H groups into poly(1-trimethylsilyl-1-propyne) and poly(vinyltrimethylsilane) leads to the appearance of proton conductivity of these polymers.     

An electrooptical method for studying the mean length of stereoblocks in poly(1-trimethylsilyl-1-propynes) and poly(1-trimethylgermyl-1-propynes)

It was shown that equilibrium electrooptical properties (the Kerr effect) in solutions of disubstituted polyacetylenes poly(1-trimethylsilyl-1-propyne) and poly(1-trimethylgermyl-1-propyne) are related to the dipole structure of these polymers that is associated with the partial spiralization of their chains. A method of estimating the length of monomer unit sequences occurring in the same spatial configuration (stereoblocks) was developed. This method is based on the experimental measurement of the specific Kerr constant of disubstituted polyacetylenes. The sizes of stereoblocks in polymer chains that were synthesized with the use of various catalysts and that differ in the mean ratio of trans: cis C=C bonds, as estimated by the electrooptical method, were compared with the X-ray diffraction data on the same film polymers. There was good agreement between the results obtained by both methods.     

Gas permeability and stability of poly(1-trimethylsilyl-1-propyne-co-1-phenyl-1-propyne) membranes

A significant reduction in the gas permeability of the poly(1-trimethylsilyl-1-propyne) (PMSP) membrane was investigated in terms of the membrane thickness and the storage environment. The effects of physical aging were observed with thinner membranes and under vacuum conditions compared with storage in air. The decrease in the permeability coefficient was dependent on the decrease in the hole saturation constant of Langmuir adsorption (C'_H), which is related to the volume of the microvoids. Physical aging in the PMSP membrane affected not only the glassy domain but also the rubbery one. To stabilize the permeability of the PMSP membrane, a poly(1-trimethylsilyl-1-propyne-co-1-phenyl-1-propyne) [poly(TMSP-co-PP)] membrane was prepared. Poly(TMSP-co-PP) has the same unit of poly(1-phenyl-1-propyne), which membrane has stable permeability. The poly(TMSP-co-PP) with less than 20 mol % PP content was estimated to be a random copolymer based on theoretical gas permeation analysis. In the poly(TMSP-co-PP) membrane, the relation between the PP content and C'_H was similar to the relation between the PP content and the gas permeability. The stability of the permeability was dependent on the PP content. The poly(TMSP-co-PP) membrane containing 10 mol % PP had both high permeability and good stability under some of the aging conditions performed in this work. © 1995 John Wiley & Sons, Inc.     

Chromatographic and adsorption properties of the mixed stationary phase poly(1-trimethylsilyl-1-propyne)/poly(1-phenyl-1-propyne)

Adsorption and chromatographic properties of the mixed stationary phase poly-(1-trimethylsilyl-1-propyne)/poly(1-phenyl-1-propyne) (PTMSP/PPP) composed as 97: 3 by weight have been investigated by methods of low-temperature nitrogen adsorption and gas chromatography on packed columns. The resultant phase has uniform mesoporous structure. The chromatographic properties of the mixed phase are significantly different from the properties of the original porous polymers PTMSP and PPP. The adsorbent obtained by modifying Chromosorb P NAW with a mixture of polymers provides the selective separation of chlorosubstituted, saturated, and aromatic hydrocarbons.     

A Fourier IR study of sorption of dibutyl phthalate from aqueous solutions with poly(1-trimethylsilyl-1-propyne) films

The dynamics of sorption of dibutyl phthalate from aqueous solutions with poly(1-trimethylsilyl-1-propyne) films was studied by Fourier IR spectroscopy. The preconcentration factors were determined. They exceed by an order of magnitude those attained with reference polymers, poly(vinyltrimethylsilane) and low-density polyethylene.     

Facilitated transport of molecular oxygen in cobaltporphyrin/poly(1-trimethylsilyl-1-propyne) membrane

The combination membrane of poly(1-trimethylsilyl-1-propyne) with enormously high permeability and poly(vinylimidazole)-bound porphinatocobalt with selective oxygenbinding ability was prepared. Oxygen transport through the membrane was facilitated in terms of oxygen transport via the latter domain as a fixed oxygen-carrier, and this oxygen permeability maintained for a month.     

Chromatographic properties and polarity evaluation of poly(1-trimethylsilyl-1-propyne) and poly(1-phenyl-1-propyne)

The chromatographic properties of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) were studied by gas chromatography using packed columns. The selectivity and efficiency of columns packed with PTMSP and PPP were compared to the data obtained for columns with other known adsorbents and stationary phases. The McReynolds and Rohrschneider constants, on the basis of which the polarity of the new phases was evaluated, were calculated. The results of the investigation of chromatographic properties allow PTMSP to be brought in line with the polymeric adsorbents Porapak Q, Porapak QS, and Chromosorb 106, while PPP, with the methyphenylsilicon phases SE-52 and OV-3.     

Effect of molecular weight on crystallization and rheological properties of poly(3,3-bis(azidomethyl)oxetane)

Various molecular weight of poly(3,3-bis(azidomethyl)oxetane) were prepared from 3,3-bis(chloromethyl) oxetane. The structure of those were confirmed by Fourier transform infrared, proton nuclear magnetic resonance spectral analysis and gel permeation chromatograph, meanwhile the properties were also compared by X-ray diffraction, differential scanning calorimetry and rheological analysis. The results indicated that increasing molecular weight weakened the crystallization ability of PBAMO and increased the glass transition temperature. Furthermore, the viscosity, shear stress, G′ and G″ of PBAMO increased gradually with increasing of the molecular weight.     

Copolymerization of 4-methyl-2-pentyne with 1-trimethylsilyl-1-propyne and 1-trimethylgermyl-1-propyne with Nb-containing catalysts

It has been shown that the copolymerization of 4-methyl-2-pentyne with 1-trimethylsilyl-1-propyne or 1-trimethylgermyl-1-propyne with the use of niobium pentachloride-based catalytic systems in the presence of Ph₃Bi, Et₃SiH, and Bu₄Sn as cocatalysts yields corresponding copolymers of various compositions. The technique of determining the composition of copolymers from their IR spectra has been developed. The reactivity ratios of the monomers have been estimated. It has been demonstrated that these values increase in a sequence 4-methyl-2-pentyne > 1-trimethylsilyl-1-propyne > 1-trimethylgermyl-1-propyne.     

Living polymerization of 4-methyl-2-pentyne and 1-trimethylsilyl-1-propyne initiated by NbCl5-Ph4Sn catalyst

The polymerization of 4-methyl-2-pentyne and 1-trimethylsilyl-1-propyne initiated by catalytic systems based on niobium pentachloride and Et₃SiH, Bu₄Sn, Ph₄Sn, and Ph₃SiH as cocatalysts has been investigated. Direct evidence for the living polymerization of 4-methyl-2-pentyne and 1-trimethylsilyl-1-propyne with the NbCl₅-Ph₄Sn catalytic system is derived. These are the linear molecular mass dependence on conversion and the continuation of chain propagation after introduction of a new monomer portion.     

Solutions of mixtures of cellulose and synthetic polymers in <Emphasis Type="Italic">N</Emphasis>-methylmorpholine-<Emphasis Type="Italic">N</Emphasis>-oxide

Phase state and morphological features of solutions of cellulose blends with rigid-chain thermotropic LC copolyesters and isotropic poly(m-phenyleneisophthalamide) in the highly polar donor solvent N-methylmorpholine-N-oxide are studied by DSC and polarization microscopy. The ternary phase diagram for the cellulose-copolyesters-N-methylmorpholine-N-oxide system is constructed. Rheological characteristics of the prepared solutions are studied using capillary and rotary rheometers under the regimes of continuous and periodic shear deformation. Rheological characteristics of cellulose solutions with copolyesters in N-methylmorpholine-N-oxide with their different phase states are shown to change in accordance with the traditional mechanism of flow for solutions with high specific interactions between their components. However, the character of the rheological behavior of mixtures of cellulose with poly(m-phenyleneisophthalamide) in N-methylmorpholine-N-oxide primarily stems from structural-morphological transformations in solutions taking place upon deformation.     

Molecular and Electrooptical Characteristics of Poly(1-trimethylsilyl-1-propynes) with Varied Chain Regularity

Samples of a disubstituted polyacetylene, poly(1-trimethylsilyl-1-propyne), containing on the average 60% of cis-C=C bonds and prepared with NbCl₅ as catalyst were studied by means of Kerr effect measurements in solution and molecular hydrodynamics methods. The resulting data were correlated with the properties of the sample prepared with another catalytic system, TaCl₅/BuLi. Samples prepared under different catalytic conditions were found to have much different electrooptical properties. It was concluded that the TaCl_5/BuLi catalyst allows preparation of polymers with longer continuous sequences of monomeric units of the same isomeric structure as compared with those obtained with NbCl₅.     

Synthesis and properties of homo- and copolymers of trifluoropropyldimethylsilyl-1-propyne with trimethylsilyl-1-propyne

Homopolymerization of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne is investigated in the presence of catalysts based on tantalum (V) chloride and niobium (V) pentachloride with various cocatalysts. As a result of homopolymerization, an insoluble polymer is formed. It is established that the insolubility of the homopolymer is connected with the presence in the polymer of “pseudocrystalline” regions playing the role of physical links. Copolymerization of 1(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and trimethylsilyl-1-propyne under the action of the TaCl₅-Ph₃Bi system is studied. The relative activity constants of monomers, whose ratio points to the formation tendency of copolymers enriched with trimethylsilyl-1-propyne at the early stages of polymerization, are estimated. It is shown that the structures and solubilities of the obtained copolymers depend on their compositions. Gas-transport and hydrophobic-hydrophilic properties for soluble samples are studied. Soluble copolymers have good film-forming properties, improved hydrophobicity, stability against hydrocarbons, and high levels of gas permeability: properties that make them promising materials for the separation of various liquids and gaseous water-organic media.     

Pure hydrocarbon sorption properties of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends

Propane and n-butane sorption in blends of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) have been determined. Solubilities of propane and n-butane increased as the PTMSP content in the blends increased. This result is consistent with the higher free volume of PTMSP-rich blends and the better thermodynamic compatibility between PTMSP and these hydrocarbons. Propane and n-butane sorption isotherms were well described by the dual-mode model for sorption in glassy polymers. PTMSP/PPP blends are strongly phase-separated, heterogeneous materials. A noninteracting domain model developed for sorption in phase-separated glassy polymer blends suggests that sorption in the Henry's law regions (i.e., the equilibrium, dense phase of the blends) is consistent with the model. However, Langmuir capacity parameters in the blends are lower than predicted from the domain model, suggesting that the amount of nonequilibrium excess free volume associated with the Langmuir sites depends on blend composition. © 1996 John Wiley & Sons, Inc.     

Synthesis and properties of brominated poly(1-trimethylsilyl-1-propyne)

Russian Chemical Bulletin - A procedure of selective bromination of poly(1-trimethylsilyl-1-propyne) using N-bromosuccinimide as the brominating agent was developed. This method allows to obtain...     

Polymerization of <Emphasis Type="Italic">p</Emphasis>-dioxanone initiated by compounds of tin and transition metals

The bulk polymerization of p-dioxanone is studied at 80 and 120°С. A high-molecular-mass poly(p-dioxanone) suitable for extrusion processing into medical devices is prepared with the use of initiating systems based on Sn(II), Sn(IV), Y(III), Zr(IV), and Hf(IV) compounds and dodecanol and oxiranes with different structures as polymerization coinitiators. For a number of polymer samples, molecular masses are determined via viscometry. New initiating systems that enable the synthesis of poly(p-dioxanone) with a logarithmic viscosity of 1.95–2.54 dL/g and a molecular mass of up to 400 kDa are proposed.     

Living Polymerization of 1-Trimethylsilyl-1-propyne and 4-Methyl-2-pentyne by NbCl5-Based Catalysts

Sequential homopolymerization of disubstituted acetylenes 1-trimethylsilyl-1-propyne and 4-methyl-2-pentyne by NbCl₅–Ph₃SiH was investigated and the main evidence of living polymerization, namely, continuation of chain propagation after addition of a new portion of monomer was observed. AB and BA type block copolymers of 1-trimethylsilyl-1-propyne and 4-methyl-2-pentyne were synthesized by sequential polymerization of these monomers in presence of NbCl₅–based catalytic systems.     

Viscosity of concentrated solutions of polystyrene and poly(vinyl acetate) (empirical equations)

The viscosity of solutions of polystyrene with M _w from 2.8 × 10⁴ to 7.8 × 10⁵ in toluene and of poly(vinyl acetate) with M _w from 2 × 10⁴ to 1.4 × 10⁵ in butyl acetate at 30–80°C is measured. The dependence of the activation energy of the viscous flow of the solutions on the molecular weight of the polymers and solution concentration is examined. This dependence is approximated by a cubic polynomial for polystyrene solutions and by a quadratic polynomial for poly(vinyl acetate) solutions. The dependences of the solution viscosity on the concentration, molecular weight, and temperature are approximated by exponential equations in which the exponents are sums of polynomials. The coefficients of the polynomials are determined.