Homo- and copolymerizations of 3-(N-carbazolyl)-1-propyne and its homologues by Mo and W catalysts

Summary 3-(N-Carbazolyl)-1-propyne polymerized with MoCl₅- and WCl₆-based catalysts to produce a polymer in high yields. The MoCl₅ and MoCl₅-n-Bu₄Sn catalysts were the most effective (the systems solidified immediately after initiation of polymerization with these catalysts). The product polymer was a yellow solid insoluble in any solvent. Copolymerization of the present monomer with tert-butylacetylene by MoCl₅-n-Bu₄Sn produced a copolymer; it had a high molecular weight (M _w 350,000), completely dissolved in toluene, CHCl₃ etc, and formed a free-standing film by solution casting. -N-Carbazolyl-1-hexyne and-1-octyne produced toluene-insoluble polymers with WCl₆-Ph₄Sn.     

Living metathesis polymerization of (p-n-butyl-o,o,m,m-tetrafluorophenyl)acetylene by MoOcl4-n-Bu4Sn-EtOH (1:1:1)

Summary Possibility of living metathesis polymerization by Mo catalysts was examined for (p-n-butyl-o,o,m,m-tetrafluorophenyl)acetylene, which has two fluorine atoms at both ortho positions. The MoOCl₄-n-Bu₄Sn-EtOH (1:1:1) catalyst yielded a polymer with narrow molecular weight distribution ( ), but the corresponding MoCl₅-based catalyst did not formed such a polymer. With the former catalyst, the number-average molecular weight of polymer increased in direct proportion to monomer conversion, while the molecular weight distribution remained narrow; this proves the livingness of the polymerization. The optimal conditions for the living polymerization were [n-Bu₄Sn]/[MoOCl₄]=∼1.0, [EtOH]/[MoOCl₄]=0.5–1.5, and temperature≤30 °C. n-Butyl acetate and acetone as well as EtOH were effective as third catalyst components.     

Polymerization of [2,5-bis(trifluoromethyl)phenyl]acetylene and polymer properties

Summary [2,5-Bis(trifluoromethyl)phenyl]acetylene [BTFPA; HCCC₆H₃-2, 5-(CF₃)₂]polymerized with W, Mo, and Nb catalysts to produce methanol-insoluble polymers in high yields. The poly(BTFPA) produced by the W(CO)₆-based catalyst at 30 °C was soluble in p-(CF₃)₂C₆H₄, and had relatively high molecular weight ([]=0.352 dL/g in p-(CF₃)₂C₆H₄). The main chain of the polymer was composed of alternating double bonds, and the polymer was a dark brown solid. The temperature at which the weight loss of the polymer started was higher than 300 °C. The polymerization behavior and polymer properties for BTFPA are compared with those for phenylacetylene and [o-(trifluoromethyl)phenyl]acetylene.     

Synthesis and properties of poly(diphenylacetylenes) having ether linkages

Summary Polymerization of 1-phenyl-2-(p-phenoxyphenyl)acetylene (p-PhODPA), 1-phenyl-2-(p-methoxyphenyl)acetylene, and 1-phenyl-2-(p-n-butoxyphenyl)acetylene was examined. These monomers polymerized with TaCl₅-n-Bu₄Sn to give methanol-insoluble polymers in over 60% yields. Poly(p-PhODPA) was a yellow solid completely soluble in toluene, CHCl₃, etc., and its weight-average molecular weight was about 1.0x10⁶ or higher. This polymer was thermally very stable (the onset temperature of weight loss in TGA in air was 420 °C). Its oxygen permeability coefficient (P o ₂) was 37 barrers (P o ₂/P n ₂ 2.2) and similar to that of natural rubber. In contrast, the other two polymers did not completely dissolve in any organic solvent, and their thermal stability was lower.     

Synthesis of poly(vinyl alcohol)s with narrow molecular weight distribution from poly(benzyl vinyl ether) precursors

Summary A series of poly(benzyl vinyl ether)s of low molecular weight (5000 to 15000 g mol^-1) and narrow molecular distribution ( ) have been synthesisedvia the cationic polymerisation of benzyl vinyl ether. Acetylation with acetic anhydride/tin (IV) chloride leads to poly(vinyl acetate), which can be hydrolysed to near-monodisperse water-soluble poly(vinyl alcohol) with an isotacticity of approximately 47%. This polymer was re-acetylated and its molecular weight distribution assessed to confirm that hydrolysis gives minimal chain scission.     

Synthesis of a cis-rich,living poly[(o-methylphenyl)acetylene] by use of the MoOCl4-n-Bu4Sn-EtOH catalyst

Summary Polymerization of (o-methylphenyl)acetylene (o-MePA) by MoOCl₄-n-Bu₄Sn-EtOH catalyst in toluene at 0°C provided a cis-rich living polymer; cis 77%, M _w/M _n=1.21. The polymerization at -30°C gave results similar to those for 0°C, whereas the polymer obtained at 30°C exhibited a broader molecular weight distribution (MWD) and a lower cis content. Among several organotin compounds, only n-Bu₄Sn was effective for the living polymerization of o-MePA. The bulkier the alkyl group of alcohols as the third catalyst component, the broader the MWD of the polymer, while the geometrical structure was not affected by the alcohols.     

Polymerization of o-chloro- and o-bromo-substituted phenylacetylenes and polymer properties

Summary (o-Chlorophenyl)acetylene (o-CIPA), (o-bromophenyl)acetylene (o-BrPA), and (o,o,p-trichlorophenyl)acetylene (Cl₃PA) polymerized in high yields in the presence of W and Mo catalysts. Nb and Ta catalysts were also effective in producing poly(Cl₃PA). Poly(o-CIPA) formed was soluble in such solvents as toluene and CHCl₃, and its maximum weight-average molecular weight was 3x10⁵. Though poly(o-BrPA) obtained with WCl₆-Ph₄Sn was soluble, those obtained with other catalysts were insolble in any solvent. Further, poly(Cl₃PA) was insoluble irrespective of the kind of catalyst. These polymers were dark brown solids and did not lose weight below 230°C, being more stable than poly(phenylacetylene).     

End-functionalized polymers by living cationic polymerization

Summary End-functionalized poly(isobutyl vinyl ether) (2) with a terminal amine, carboxylic acid, or ester group was prepared by quenching the HI/I₂-initiated living polymer ends with ring-substituted anilines (H₂N-C₆H₄-X, p or m; X = NH₂, COOH, COOC₂H₅). The living polymerization of isobutyl vinyl ether and the subsequent end-capping reaction were carried out at –15°C in methylene chloride. The resulting polymers exhibited a narrow molecular weight distribution and carried one terminal function (aniline residue) per chain, according to ¹H NMR structural analysis.     

Influence of solvent and molecular weight on thickness and surface topography of spin-coated polymer films

The influence of polymer molecular weight, molecular weight distribution, and polymer-solvent interactions on the thickness and topography of spin-coated polymer films was examined. For films prepared from dilute solutions, highly volatile solvents or fair or “poor” solvents for the polymer adversely affect film surfaces causing nonuniformities (waves) to appear. However, if the concentration of these solutions is increased to approximately the concentration at which entanglements are formed, nearly uniform films are produced even if the solvent employed is highly volatile, such as dichloromethane. When toluene is employed as the solvent, which has a relatively low volatility and therefore forms nearly flat film surfaces, films prepared from dilute solution were found to have thicknesses, h, proportional to η Ω^?0.49 for polystyrene and η Ω^?0.49 for poly(methylmethacrylate) where η_o is the zero-shear rate solution viscosity and Ω is the rotational speed at which the films were prepared. These results suggest that the exponents associated with η_o and Ω may be nearly independent of the type of polymer used as long as flat films are produced. Finally, the molecular weight parameter most important in controlling final film thickness for films made from dilute solutions is M_v, the viscosity-average molecular weight.     

Polymerization of propiolic acid and its derivatives catalysed by MoCl5

The polymerization of propiolic acid by group VI and VIII transition metal catalysts was investigated. MoCl₅, which was the most active among the catalysts examined, provided poly (propiolic acid) in over 80% yields under favourable conditions. The polymer formed was a water-soluble tawny powder, and its molecular weight was low ($\text{η}{}_{\mathrm{<mtext>sp</mtext>}}\text{C}\text{0.04–0.05}\text{dl g}{}^{\mathrm{?1}}$). The polymer structure,

was confirmed by the i.r. and ¹³C n.m.r. spectra and elemental composition. Some derivatives of propiolic acid (methyl propiolate, acetylenedicarboxylic acid, and phenylpropiolic acid) also produced coloured powdery polymers in the presence of MoCl₅-based catalysts.     

Synthesis and gas permeability of ester substituted poly(p-phenylene)s

Polymerizations of various ester substituted 2,5-dichlorobenzoates [substituent: linear alkyl groups (1a-f), branched alkyl groups (1g-l), cyclohexyl groups (1m-o), phenyl groups (1p-r), and oxyethylene units (1s-v)] were investigated with Ni-catalyzed/Zn-mediated system in 1-methyl-2-pyrrolidone (NMP) at 80 °C. Most of monomers bearing linear and branched alkyl groups successfully polymerized to give relatively high-molecular-weight polymers (M_n = 10,000-20,800). However, the molecular weight of the polymer having eicocyl groups was low because of steric hindrance of long alkyl chain. The polymerizations of cyclohexyl 2,5-dichlorobenzoate and phenyl 2,5-dichlorobenzoate produced low-molecular-weight polymers, while the polymerizations of monomers with alkyl cyclohexyl and alkyl phenyl groups proceeded to afford polymers with relatively high-molecular-weights. The polymers possessing oxyethylene units were obtained, but the molecular weights were low when the oxyethylene chains were long. The gas permeability of membranes of poly(p-phenylene)s with alkyl chains increased as increasing the length of alkyl chain. The membranes of poly(p-phenylene)s with phenyl groups and oxyethylene units exhibited high densities and relatively low gas permeability. However, the CO₂/N₂ separation factor of membrane of poly(p-phenylene) having oxyethylene units was as large as 73.6.     

Synthesis and characterization of poly(1,8-diethynylnaphthalene)

Summary The cyclopolymerization of 1,8-diethynylnaphthalene(DEN) and its copolymerization with diethyl dipropargylmalonate(DEDPM) were carried out by various transition metal catalysts. MoCl₅-based catalyst was found to be very effective and gave almost a quantitative polymer yield. The resulting dark-brown homopolymer(PDEN) was partially soluble in chloroform, tetrahydrofuran, and dimethyl sulfoxide, whereas copolymer (1:1) with number avaerage molecular weight of 2.1x10⁴ by GPC showed good solubility in those solvents. The structure of the polymers was analysed by IR, NMR, and UV-VIS spectroscopies. From the spectral and solubility data, it is proposed that cyclized products with the conjugated system are formed. Room temperature conductivities of the I₂-doped homo and copolymer were found to be about 7.5x10^-3 and 5.1x10^-3 S/cm, respectively.     

Polymerization of substituted acetylenes by (mesitylene)M(CO)3 (M=W,Mo)

Summary Phenylacetylene could be polymerized by (mesitylene)W(CO)₃ in CCl₄ to give a polymer with 12,000 in ca. 80% yield. UV irradiation was unnecessary unlike the W(CO)₆–CCl₄-h catalyst. The present polymerization did not proceed in toluene. The (mesitylene)W(CO)₃ catalyst afforded high molecular weight polymers from phenylacetylenes bearing bulky substituents (e.g., Me₃Si and CF₃) at the ortho position. The Mo counterpart, (mesitylene)Mo(CO)₃, catalyzed the polymerization of 1-chloro-2-phenylacetylene and 1-chloro-1-octyne to provide high molecular weight polymers . Catalytic amounts of Lewis acids accelerated the polymerization of phenylacetylene by (mesitylene)W(CO)₃, but decreased the polymer molecular weight; this polymerization proceeded not only in CCl₄ but also in toluene.     

Polymer Complexes. XLIII. EPR, Spectra, and Stereochemical Versatility of Novel Copper(II)Polymer Complexes

Copper(II) polymer complexes of empirical formula [Cu(ligand)₂X₂] (where X = Cl, Br, I, NO₃, and SO₄) and [Cu(ligand)(CH₃COO)₂] have been prepared with poly(3-phenylacrylidine semicarbazone). All the polymer complexes prepared have been characterized by elemental analysis, magnetic moment, conductance, IR, electronic, ¹H-NMR, and electronic paramagnetic resonance spectral studies. The polymer complexes [Cu(ligand)₂X₂] and [Cu(ligand) (CH₃COO)₂] may have tetragonal symmetry while the [Cu(ligand)₂( SO₄)₂] may be five-coordinate trigonal bipyramidal in structure. All complexes exhibit normal magnetic moments corresponding to one unpaired electron except [Cu(ligand)(CH₃COO)₂] which shows a subnormal magnetic moment. EPR spectra of the polymer complexes have been studied with a view to assigning their stereochemistries. Various EPR parameters have been calculated. The g, A, G values for all the polymer complexes are consistent with a tetragonal 1–5 and trigonal bipyramidal 6 stereochemistry in the Cu(II) polymer complexes of homopolymer.     

Synthesis and characterization of new side chain liquid crystalline polymers based on poly(dipropargylamine) main chain

Summary A new thermotropic side-chain liquid crystalline polymers based on poly (dipropargylamine) backbone were prepared by metathesis polymerization with transition metal catalysts. It was found that the MoCl₅-EtAlCl₂ catalyst system were very effective for the cyclopolymerization of presently investigated monomers. Resulting polymers were soluble in common organic solvents such as THF, chloroform, etc. The number-average molecular weight ( ) values of the polymers were in the range of 6.49x10³–11.6x10³, relative to polystyrene standard by GPC. Thermal properties of the monomers and the polymers synthesized were examined by differential scanning calorimetry (DSC) and cross-polarized optical microscopy. Both monomer and polymer displayed enantiotropic liquid crystallinity showing the reversible phase transition.     

Synthesis of poly(tetrahydrofuran-b-ε-caprolactone) macromonomer via the Sml2-induced transformation

Summary A novel well-defined macromonomer consisting of different types of monomers in polymerization mechanisms was synthesized for the first time through the SmI₂-induced transformation. The macromonomer, -methacryloylpoly-(tetrahydrofuran-b--caprolactone), was prepared by the reaction of methacryloyl chloride with living poly(tetrahydrofuran-b--caprolactone) [poly(THF-b-CL)] which was obtained by the two-electron reduction of the cationic growing center of poly(THF) by samarium iodide (SmI₂) followed by the polymerization of CL. ¹H NMR analysis indicated the quantitative introduction of the methacryloyl group onto the polymer end. The molecular weight distribution of the macromonomer was relatively narrow, and the unit ratio of THF to CL could be controlled by both polymerization time of THF and the amount of CL, resulting from the living nature of both CL- and THF-polymerizations. Radical copolymerization of the produced macromonomers with methyl methacrylate in the presence of AIBN resulted in a polymethacrylate backbone grafted with poly(THF-b-CL) block copolymers.     

Functionally substituted tetramethylcyclopentadienes: Synthesis of 1-(p-hydroxyphenyl)-2,3,4,5-tetramethylcyclopentadiene and its use in the synthesis of an organometallic polymer

Reaction of 2,3,4,5-tetramethylcyclopent-2-enone (1) withp-LiC₆H₄OC-Me₂OMe, followed by treatment with aqueous acid afforded 1-(p-hydroxyphenyl)-2,3,4,5-tetramethylcyclopentadiene (2). This new ligand was then used in the synthesis of the functionally substituted organomolybdenum reagent (⁵-C₅Me₄-p-C₆H₅OH)Mo(CO)₂(NO) (3). Treatment of a preformed 1/1 styrene/maleic anhydride copolymer ( ) with 5 mol% 3 led to chemical incorporation of the organometallic species into the polymer. The final product contained 3 mol% of the organometallic moiety.     

The role of hindered Lewis bases on the catalyst performance of TiCl3 for propylene polymerization

Summary The effect of AlEt₃ modified by tributylamine (TBA), 1,4-diazabicyclo [2.2.2]octan (DO), 2,2,6,6-tetramethylpiperidine (TMPip), 2,6-dibutyl-4-methylphenol (BHT) and 2-tert-butyl-4-metoxyphenol (TBMP) on the propylene polymerization was studied using a catalyst based on TiCl₃ modified with di-n-butyl ether as internal base. The influence of these hindered Lewis bases on the isotacticity, catalyst activity, molecular weight ( n) and molecular weight distribution (MWD) was investigated. It was verified that the Lewis bases modified the percentage of mm triad whereas no significant effect on I.I. was found.     

The performance of porous and gauze electrodes in electrolysis with parabolic velocity distribution

An approximate numerical method for the estimation of the velocity exponent in (small-scale) flow-through porous and gauze electrodes is presented. The method can also be employed to determine if a plug-flow or a parabolic-flow model offers a more reliable representation of the experimental behaviour of the electrode.Nomenclature a cross sectional area of the electrode - B integration parameter (Equations 7 and 8) - c exit active ion concentration, its mean measured value in the case of parabolic flow,c _o its inlet value;c _m its mean value; its mean calculated value in the case of parabolic flow;c ^* dimensionless concentration, equal toc/c _o; mean dimensionless concentration, equal to /c _o - F Faraday's constant - i _L mean limiting current density (geometric-area base) - j proportionality factor (Equation 1) - k _m mass transport coefficient, its mean value - L length of the electrode - n number of electrons involved in the electrode reaction - N ionic flux - r radial coordinate - R _E geometric radius - R limiting degree of conversion - s specific surface area of the electrode (surface per volume) - u linear solution velocity; u_o its maximum (centreline) value; its mean value (=u_o/2) - v volumetric flow rate; its mean value - x transform variable forz - z dimensionless radial distance - velocity exponent for mass transport (Equation 1)     

Synthesis and properties of a new side chain liquid crystalline polymer by methathesis polymerization

Summary Novel liquid crystalline monomer, 4-methoxybiphenyloxy-(N,N-dipropargyl)undecane amide, subjected to metathesis reaction with transition metal catalyst systems. It was found that the MoCl₅-EtAlCl₂ catalyst system was very effective for the cyclopolymerization of the monomer. Resulting polymers exhibited good solubility in common organic solvents such as THF, chloroform, etc. The number-average molecular weight (Mn) values of the polymers were in the range of 0.98x10⁴–1.4x10⁴, relative to polystyrene standard by GPC.Thermal properties of the monomer and the polymer synthesized were examined by differential scanning calorimetry (DSC) and cross-polarized optical microscopy. The polymer exhibited the enanfiotropic liquid crystallinity and smectic mesophase.