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.     

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.     

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.     

Phase equilibrium and rheology of poly(1-trimethylsilyl-1-propyne) solutions

The phase equilibrium and rheological properties of poly(1-trimethylsilyl-1-propyne) solutions obtained with tantalum catalysts are studied. For three polymers with different molecular masses, phase diagrams are determined in a number of solvents. From these diagrams, the Hansen solubility parameters of poly(1-trimethylsilyl-1-propyne) are calculated by the method proposed in this work. Dilute solutions of poly(1-trimethylsilyl-1-propyne) behave as Newtonian liquids, whereas the viscosity of viscoelastic concentrated systems decreases as the shear rate grows. The molecular and rheological characteristics of studied poly(1-trimethylsilyl-1-propyne) samples are compared with the samples prepared with NbCl₅ catalysts. Poly(1-trimethylsilyl-1-propyne) obtained with a catalytic system involving tantalum pentachloride is characterized by high intrinsic viscosity and solution viscosity compared to poly(1-trimethylsilyl-1-propyne) prepared with niobium catalyst. The difference in properties is due to the dissimilar ratios of cis and trans units in the samples.     

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.     

Copolymers of 1,2-disubstituted acetylenes containing trifluoropropyl groups synthesized in the presence of NbCl<Subscript>5</Subscript>-based catalyst systems: Structure and gas-transport behavior

Using a NbCl₅-based catalyst system, random copolymers of 1-(3,3,3-trifluoropropyldimethylsilyl)-1-propyne and 1-trimethylsilyl-1-propyne are synthesized in a wide range of comonomer contents. The dependences of gas-transport behavior on the composition and supramolecular organization of the copolymer are studied. Composition regions and conditions of preparing copolymers combining high permeability coefficients with resistance against nonpolar organic solvents are ascertained. The copolymers demonstrate a high selectivity in the separation of butane from a methane–butane mixture.     

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.     

GAS PERMEABILITY OF COPOLY(1-TRIMETHYL-SILYL-1-PROPYNE-PENTAMETHYL-DISILYL-1-PROPYNE) MEMBRANE

The permeability of copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane for twelve gases (0_2, N_2, CO_2, H_2, D_2, He, At, CH_4, C_2H_4, C_2H_6, C_3H_6 and C_3H_8) was examined. The basic laws of solution and diffusion of the gases in the membrane were expounded preliminarily. It was found that a linear relationship between logarithm of diffusion coefficient (D) and critical molar volume (V_c) of the gases. The permeation characteristics of the gases in the copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane was also discussed.     

Silica filled poly(4-methyl-2-pentyne) nanocomposite membranes: Similarities and differences with poly(1-trimethylsilyl-1-propyne)–silica systems

The performance of poly(4-methyl-2-pentyne) (PMP)/silica nanocomposites was studied for membranes with a filler content between 10 and 40 wt%. An increase in permeability and a constant vapor selectivity were measured with increasing filler content. The constant selectivity was in contrast to earlier published results for silica filled poly(1-trimethylsilyl-1-propyne) (PTSMP) membranes. Therefore, a comparison between both materials was made. Free volume sizes and interstitial mesopore sizes were determined by use of positron annihilation lifetime spectroscopy (PALS) and image analysis was performed on transmission electron microscopy (TEM) pictures of both materials. Although both materials possessed interstitial mesopores, a difference in membrane structure was noticed, explaining the difference in membrane performance.     

Extraction of butanol from aqueous solutions by pervaporation through poly(1-trimethylsilyl-1-propyne)

Poly(1-trimethylsilyl-1-propyne) (PTMSP) was synthesized using a TaCl₅–Al(i-Bu)₃ catalysis system. Pervaporation and sorption of n-butanol–water mixtures were studied, and the peculiarities of water and butanol co-permeation are discussed. The strong dependence of water partial flux (with a minimum at 1 wt.% butanol in feed) on butanol concentration in feed was observed. S-shaped isotherms of butanol and total sorption were found for PTMSP in 0–1 wt.% concentration range. It appears that blocking of PTMSP nanopores by high sorbing organic molecules controls the pervaporation of butanol from dilute aqueous solutions. Data are discussed in regard with PTMSP morphology.     

The polymerization of 3-chloro-1-propyne and 3-bromo-1-propyne with Mocl5 and WCL6 based initiators and the structure of the resulting polymers

The WCl₆ and MoCl₅ initiated polymerizations of 3-chloro-1-propyne and 3-bromo-1-propyne were performed in both halogenated and aliphatic non-nucleophilic and in aromatic nucleophilic solvents. The structure of the obtained polymers suggested that the polymerization reaction occurs in two steps. In both nucleophilic and non-nucleophilic solvents, the first step consists of the metathesis polymerization of 3-chloro(bromo)-1-propyne followed by electrophilic cis–trans isomerization leading to polymers containing trans-cisoidal allyl chloride or bromide structural units. When the polymerization is performed in non-nucleophilic solvents, in the second step an intramolecular electrophilic addition followed by elimination takes place. The resulting polymers contain a highly conjugated cyclopentadiene ladder structure. When the polymerization is performed in nucleophilic aromatic solvents, the intramolecular electrophilic addition competes with the electrophilic substitution of the solvent resulting in polymers containing high concentrations of arylpropenyl structural units. Subsequently, depending on the nucleophilicity of the polymerization solvent, the polymer structure contains structural units based on cyclopentadiene and/or arylpropenyl groups.     

Synthesis and gas permeation properties of poly(4-methyl-2-pentyne)

Poly(4-methyl-2-pentyne) [PMP] is an amorphous, glassy, di-substituted acetylene-based polymer. PMP has a low density of 0.78 g/cm³ and a high fractional free volume of 0.28. The permeabilities for helium, hydrogen, nitrogen, oxygen, carbon dioxide, methane, ethane, propane, and n-butane were determined at temperatures from 20 to 65°C and pressures from 10 to 150 psig. PMP is the most permeable purely hydrocarbon-based polymer known; its permeabilities are only exceeded by poly(1-trimethylsilyl-1-propyne) [PTMSP] and poly(1-trimethylgermyl-1-propyne) [PTMGeP]. The oxygen permeability of PMP at 25°C is 2700 × 10⁻¹⁰ cm³(STP) cm/cm² s cmHg and the nitrogen permeability is 1330 × 10⁻¹⁰ cm³(STP) cm/cm² s cmHg. The high gas permeabilities in PMP result from its very high free volume, and probably, interconnectivity of the free-volume-elements. For a glassy polymer, PMP exhibits unusual organic vapor permeation properties. Permeabilities in PMP are higher for large, condensable gases, such as n-butane, than for small, permanent gases such as helium. The permeabilities of condensable gases and permanent gases decrease as the temperature is increased. This behavior is completely unexpected for a glassy polymer and has been observed previously in only high-free-volume glassy PTMSP.     

Synthesis,structure, and properties of poly[1‐(trimethylgermyl)‐1‐propyne]

Polymerization of 1‐(trimethylgermyl)‐1‐propyne (TMGP) with TaCl₅ and NbCl₅ produced a colorless polymer in high yields, whose molecular weight reached about 3 × 10⁵–14 × 10⁵. The molecular weight distribution of the poly(TMGP) with NbCl₅ in cyclohexane was somewhat narrow (M_w /M_n = ∼1.54). The TaCl₅‐based poly(TMGP) dissolved in toluene, chloroform, cyclohexane, carbon disulfide, carbon tetrachloride, tetrahydrofuran, hexane, and so forth; the NbCl₅‐based polymer was less soluble and did not dissolve in hexane, despite its lower molecular weight. The cis contents of the NbCl₅‐ and TaCl₅‐based poly(TMGP)s determined by ¹³C NMR were 67 ± 5 and 28 ± 3%, respectively. The onset temperature of the weight loss of poly(TMGP) in air was 350 °C, indicating fair thermal stability. The oxygen permeability coefficient (P) of poly(TMGP) at 25 °C was 7800 barrer after the methanol conditioning, and the permeability was fairly stable to aging. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2964–2969, 2000     

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.     

Cationic and free-radical polymerization of optically active 1-olefins

The AlCl₃-initiated cationic polymerization of optically active 1-olefins yields polymers of varying optical rotatory power. Polymers of (+)-3-methyl-1-pentene and (?)-4-methyl-1-hexene prepared between ?78 and ?55°C. in CH₂Cl₂ or n-heptane are almost completely optically inactive. Under identical reaction conditions (+)-5-methyl-1-heptene gives polymers of significant optical rotatory power. Alternating SO₂copolymers of the same olefins, formed in reactions which proceed through free-radical intermediates, yield optically active products with specific rotations similar to those of low molecular weight analogs. These results are consistent with a cationic polymerization mechanism in which the growing chain undergoes intramolecular hydride shift and the asymmetric carbon atoms are converted into carbonium ions. The data also provide evidence for the lack of rearrangement in free-radical polymerization. By comparing the specific rotations of the cationic and free-radical polymers, the extent of rearrangement during cationic polymerization can be estimated. The calculations show that the 1,2-polymer in cationic poly-3-methyl-1-pentene is less than 2%, the sum of 1,2- and 1,3-polymer in cationic poly-4-methyl-1-hexene is less than 4%, and the sum of 1,2-, 1,3-, and 1,4-polymer in cationic poly-5-methyl-1-heptene is 14–20%.     

POLYCYCLOTRIMERIZATION OF DIYNES,A NEW APPROACH TO HYPERBRANCHED POLYPHENYLENES*

Polycyclotrimerization of diynes was explored as a new route to hyperbranched polymers in thisinvestigation. Polymerization of terminal diynes of 1,8-nonadiyne and 1,9-decadiyne was studied usingTaCl_5, NbCl_5, Mo(CO)_4(nbd) and [Mo(CO)_3cp]_2 as catalysts (where nbd = 2,5-norbornadiene, cp = cyclo-pentadiene). A soluble polymer was obtained when the polymerization of 1.9-decadiyne was initiated byTaCl_5 at low temperature (0℃). The polymer, however, became partially soluble after purification, possiblydue to the postpolymerization-induced crosslinking. NbCl_5-catalyzed polymerization of 1,9-bis(trimethylsilyl)-1,8-nonadiyne gave a completely soluble polymer. Soluble polymers were also obtainedfrom the polymerization of 3,9-dodecadiyne initiated by NbCl_5, Mo(CO)_4(nbd), [Mo(CO)_3cp]_2, PdCl_2-ClSiMe_3 and Pd/C-ClSiMe_3. IR, UV, and NMR spectroscopic analysis revealed that different catalysts gavepolymers with different structures, ranging from linear polyenes to hyperbranched polyphenylenes. Thepolymers absorb UV light at around 250 nm and emit fluorescence at 340 nm when they are excited at 248nm.     

Monomer-isomerization polymerization. XVI. Monomer-isomerization polymerization of methylpentenes with Ziegler-Natta catalyst

The polymerizations of 4-methyl-1-pentene(4M1P), 4-methyl-2-pentene (4M2P), 2-methyl-2-pentene (2M2P), and 2-methyl-1-pentene (2M1P) with Ziegler-Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl₃–(C₂H₅)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl₃–(C₂H₅)AlCl–(PPh₃)₂PdCl₂ and TiCl₃–(C₂H₅)AlCl–Ni(SCN)₂ polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer-isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a direct one-step isomerization mechanism.     

ORGANIC PERMSELECTIVE PERVAPORATION CHARACTERISTICS OF POLY(SILYLPROPYNE) AND COPOLYMER DENSE MEMBRANES

An investigation into the organic permselective separation through poly [1-trimethylsilyl-1-propyne] (PTMSP) and (1-trimethylsily1)-1-(1-penta-methyl-disilyl)-1-propyne copoly-mer (TMSP-PMDSP) dense membranes was made to gain an insight into the effect ofthe chemical structure of membrane materials on pervaporation (PV) characteristics. Theresults show that the copolymer has a higher separation factor α_(org/water) but with a rela-tively lower value of flux J_t (g/m~2·h) than pure PTMSP. This phenomenon may be at-tributed to the introduction of side chain with large bulk volume in copolymer, whichbrought about a decrease of excess free volume and the improvement of diffesion selectivityto some extent. With the same molar concentration of organic liquids in feed, THF/watersolutions have the highest value of α_(org/water) as well as J_t in comparison with ethanol/water,iso-propanol/water and THF/water mixtures.     

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.     

Synthese und Struktur von [(Me2PhP)3Cl2ReN]2NbCl4 und [Re3N3Cl5(PMe2Ph)6][NbCl6]

Synthesis and Structure of [(Me₂PhP)₃Cl₂ReN]₂NbCl₄ and [Re₃N₃Cl₅(PMe₂Ph)₆][NbCl₆] The reaction of ReNCl₂(PMe₂Ph)₃ with NbCl₅ in toluene yields the trinuclear complexes [(Me₂PhP)₃Cl₂ReN]₂‐ NbCl₄ (1) and [Re₃N₃Cl₅(PMe₂Ph)₆][NbCl₆] ( 2 ). 1 forms triclinic crystals with the composition 1 · 2 C₇H₈ (P 1, a = 1074.5(1), b = 1289.1(2), c = 1299.3(2) pm, α = 85.25(2)°, β = 81.04(2)°, γ = 86.02(1)°, Z = 1). In the centrosymmetric compound 1 two complexes ReNCl₂(PMe₂Ph)₃ coordinate with their nitrido ligands a square planar, central unit NbCl₄ to form an almost linear arrangement Re≡N–Nb–N≡Re. The length of the Re–N triple bonds is 172,2 pm, and the Nb–N distances of 216.0 pm correspond to coordinative single bonds. 2 forms orthorhombic crystals with the space group P2₁2₁2₁ and a = 1286.0(1), b = 2109.2(4), c = 2436.2(3) pm, Z = 4. The three Re atoms are located at the corners of a triangle. They are connected by two asymmetric nitrido bridges and two asymmetric chloro bridges. The weakly bent nitrido bridges (Re–N–Re = 152° and 157°) are characterized by Re–N distances of 169 und 207 pm as well as 171 and 207 pm. Re1, in addition, binds a terminal nitrido ligand with Re1–N1 = 166 pm.