Radical polymerization of (trimethylsilylethynyl)styrene and thermal properties of polystyrene with ethynyl group

The radical polymerizations of 2-, 3-, and 4-(trimethylsilylethynyl)styrenes (1 a – c) and copolymerizations of 1 a – c (M₁) with styrene (M₂) have been studied. Copolymerization parameters were determined as r₁ = 1.22 and r₂ = 0.54 for 1 a, ₁ = 1.10 and r₂ = 0.90 for 1 b, and r₁ = 1.42 and r₂ = 0.38 for 1 c. The deprotection of the trimethylsilyl groups in poly[(trimethylsilylethynyl)styrene] (2 a – c) and poly[(trimethylsilylethynyl)styrene-co-styrene] (4 a – c) using (C₄H₉)₄NF smoothly proceeded to yield poly(ethynylstyrene) (3 a – c) and poly(ethynylstyrene-co-styrene) (5 a – c), respectively, which underwent curing reactions at elevated temperature to form crosslinking polystyrenes. Received: 31 March 1997/Revised: 2 June 1997/Accepted: 3 June 1997     

Synthesis of poly(succinimide-amide) by acid-catalyzed polycondensation of L-aspartic acid and aromatic aminocarboxylic acid

Summary The polycondensations of L-aspartic acid (1) with aromatic aminocarboxylic acid, 4-aminobenzoic acid (2a), 4-aminophenylacetic acid (2b), 4-aminomethylbenzoic acid (2c), 4-(4-aminophenyl)butyric acid (2d), and 4-aminocinnamic acid (2e) were carried out using phosphoric acid as a catalyst. The obtained copolymers consiting of the succinimide and amide units, poly(succinimide-co-amide) (3), were soluble in DMF and DMSO except for that with 2e. The thermal properties differed with varying the 2 unit in 3, i.e., the T_gs of 3a–c (99 ∼ 138°C) were higher than those of 3d (81 ∼ 1 01°C), the apparent difference in the T_m between 3a–d did not observed, and the T_d decreased in the order of 3a, 3c > 3d > 3b. Received: 24 February 1998/Revised version: 3 April 1998/Accepted: 13 April 1998     

Steric effect in the free radical polymerization of vinyl ethers containing electron-deficient olefin groups

Summary o-(2-Vinyloxyethoxy)benzylidenemalononitrile (3a), methyl o-(2-vinyloxyethoxy)benzylidenecyanoacetate (3b), 1,3-di-(2'-dicyanovinyl)-5-methyl-2-(2'-vinyloxyethoxy)benzene (4a), methyl 1,3-di-(2'-carbomethoxy-2'-cyanovinyl)-5-methyl-2-(2'-vinyloxyethoxy)benzene (4b), 2,3,4-tri-(2'-vinyloxyethoxy)benzylidenemalononitrile (5a), methyl 2,3,4-tri-(2'-vinyloxyethoxy)benzylidenecyanoacetate (5b), 2,4,6-tri-(2'-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl 2,4,6-tri-(2'-vinyloxyethoxy)benzylidenecyanoacetate (6b) were prepared by the condensation of o-(2-vinyloxyethoxy) benzaldehyde (1a), 2-(2'-vinyloxyethoxy)-5-methylisophthaldehyde (1b), 2,3,4-tri-(2'-vinyloxyethoxy)benzaldehyde (2a), 2,4,6-tri-(2'-vinyloxyethoxy)benzaldehyde (2b) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether compounds 3a–b and 5a–b were polymerized readily by free radical initiators to give optically transparent swelling poly(vinyl ethers) 7a–b and 9a–b. Compounds 4a–b and 6a–b did not polymerize by radical initiators due to the steric hindrance. Polymers 7a–b and 9a–b were not soluble in common organic solvents such as acetone and DMSO due to crosslinking. Polymers 7a–b and 9a–b showed a thermal stability up to 300°C in TGA thermograms. Received: 1 December 1999/Revised version: 14 February 2000/Accepted: 16 February 2000     

Synthesis and characterization of polyimides based on isopropylidene-containing bis(ether anhydride)s

Two bis(ether anhydride)s, 4,4′-[1,4-phenylenebis(isopropylidene-1,4-phenyleneoxy)]-diphthalic anhydride (IV _a) and 4,4′-[isopropylidenebis(1,4-phenylene)dioxy]diphthalic anhydride (IV _b), were prepared in three steps starting from the nucleophilic nitrodisplacement reaction of 4-nitrophthalonitrile with α,α ′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene (I _a) and 4,4′-isopropylidenediphenol (I _b) in N,N-dimethylformamide (DMF) in the presence of potassium carbonate. The bis(ether anhydride)s IV _a and IV _b were polymerized with various aromatic diamines to obtain two series of poly(ether amic acid)s VI _a–g and VII _a–g with inherent viscosities in the range of 0.30∼0.74 and 0.29∼1.01 dL/g, respectively. The poly(ether amic acid)s were converted to poly(ether imide)s VIII _a–g and IX _a–g by thermal cyclodehydration. Most of the poly(ether imide)s could afford flexible and tough films, and they showed high solubility in polar solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide, and m-cresol. The obtained poly(ether imide) films had tensile strengths of 45∼83 MPa, elongations-to-break of 6∼27%, and initial modulus of 0.6∼1.7 GPa. The T_gs of poly(ether imide)s VIII _a–g and IX _a–g were in the range of 194∼210 and 204∼243 °C, respectively. Thermogravimetric analysis (TG) showed that 10% weight loss temperatures of all the polymers were above 500 °C in both air and nitrogen atomspheres.     

Synthesis and properties of copolymers from diphenylacetylene having a hexaphenylbenzene moiety

Summary Copolymerization of diphenylacetylene having a hexaphenylbenzene group, 1-[p-(pentaphenyl)phenyl]-2-phenylacetylene (1), with a few other diphenylacetylene derivatives (i.e., diphenylacetylene, 1-phenyl-2-[p-(trimethylsilyl)phenyl] acetylene, 1-phenyl-2-[p-n-octylphenyl]acetylene, (2a–c, respectively) and properties of the formed copolymers were investigated. No polymer was obtained in homopolymerization of 1 with TaCl₅-n-Bu₄Sn catalyst owing to steric hindrance. On the other hand, copolymerization with 2a–c proceeded at various feed ratios to give copolymers in moderate yields. Copoly(1/2a) (feed ratio 25/75) was soluble in toluene and CHCl₃ and its weight-average molecular weight (M _w) was ca. 31×10⁴ and relatively high. Copoly(1/2b) and copoly(1/2c) (both feed ratios 5/95) were soluble in common organic solvents, and had a large M _w up to ca. 1×10⁶. These copolymers were yellow to orange solids. Oxidative cyclodehydrogenation of hexaphenylbenzene groups in copoly(1/2a) was attempted in order to convert them into more conjugated groups. Received: 24 January 2000/Accepted: 17 February 2000     

Gas permeation properties of poly(2,5-dialkyl-p-phenyleneethynylene) membranes

Dipropynylbenzenes with alkyl groups (CH₃C ≡ CRC₆H₂RC≡CCH₃, R=n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁, 1a–c, respectively) were polymerized with Mo(CO)₆ to afford solvent-soluble poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c). The polymers (2a–c) had high molecular weight over 3×10⁴, and gave free-standing membranes by solution casting method. According to thermogravimetric analysis (TGA), these poly(p-phenyleneethynylene)s showed high thermal stability (T₀ ≥380 °C). The densities of membranes of poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c) were 0.936–0.965, and their fractional free volume (FFV) were relatively large (ca. 0.14–0.15). The oxygen permeability coefficients (PO₂) of membranes of 2a–c were 4.88, 7.06, and 16.6 barrers, respectively.     

A new modification of silicon carbide with a rhombic lattice

Data of an x-ray structural study of single crystals of silicon carbide α-SiC(6H) and a new, previously unknown modification γ-SiC with a rhombic lattice are described. The rhombic-lattice parameters are related to the parametera of the hexagonal and cubic lattices of SiC in the following way:a _r=a _h,b _r=3a _h,c _r=3a _c. Translated from Steklo i Keramika, No. 3, pp. 19 – 22, March, 2000.     

Synthesis and characterization of poly(meth)acrylates containing tricyanocyclopropane ring for piezoelectric applications

Summary p-(2,2,3-Tricyano-3-carbomethoxycyclopropyl)phenoxyethyl acrylate (5a) and p-(2,2,3-tricyano-3-carbomethoxycyclopropyl)phynoxyethyl methacrylate (5b) were prepared by the reactions of bromomalononitrile with methyl p-(2-acryloyloxyethoxy)benzylidene-cyanoacetate (4a) and methyl p-(2-methacryloyloxyethoxy)benzylidenecyanoacetate (4b), respectively. Monomers 5a and 5b were polymerized with free-radical initiators to obtain the polymers with multicyanocyclopropane functionalities in the pendant group. The resulting polymers 6a and 6b were soluble in acetone and the inherent viscosities were in the range of 0.20–0.25 dL/g. Solution-cast films showed T _g values in the range of 130–150°C and piezoelectric coeffcients (d₃₁) of the poled films were 1.5–1.6 pC/N, which are acceptable for piezoelectric device applications. Received: 28 April 2000/Accepted: 26 June 2000     

Synthesis of poly(ethyl vinyl ethers) containing two dipolar electronic systems and their properties

Summary 5-Nitro-2-(2′-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 5-nitro-2-(2′-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3-nitro-4-(2′-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3-nitro-4-(2′-vinyloxyethoxy)benzylidenecyanoacetate (4b) were prepared by the condensation of 5-nitro-2-(2′-vinyloxyethoxy)benzaldehyde (1) and 3-nitro-4-(2′-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Vinyl ether monomers 2a-b and 4a-b were polymerized with boron trifluoride etherate as a cationic initiator to yield poly(vinyl ethers) 5-6 having nitrooxybenzylidenemalononitrile and nitrooxycyanocinnamate, which is effective chromophore for second-order nonlinear optical applications. Polymers 5-6 were soluble in common organic solvents such as acetone and DMSO. T _g values of the resulting polymer were in the range of 70–81°C. Electrooptic coefficient (r₃₃) of the poled polymer films were in the range of 19–27 pm/V, which was improved by introducing of nitro group. Polymers 5–6 showed a thermal stability up to 300°C in TGA thermograms, which is acceptable for NLO device applications. Received: 24 November 1998/Revised version: 19 January 1999/Accepted: 29 January 1999     

Cyclodextrins in polymer synthesis: Influence of methylated β-cyclodextrin as host on the free radical copolymerization reactivity ratios of hydrophobic acrylates as guest monomers in aqueous medium

Summary Methylated (β-cyclodextrin (me-β-CD) was used to complex the hydrophobic monomers n-butyl acrylate (1), n-hexyl acrylate (2) and cyclohexyl acrylate (3) yielding the corresponding water soluble host/guest complexes 1a–3a. The complexes were copolymerized in water by free radical mechanism and the reactivity ratios were determined by measuring the monomer consumption by HPLC. The following reactivity ratios were found: copolymerization of 1a and 2a: r₁= 1.01 ± 0.01; r₂= 1.04 ± 0.01; copolymerization of 3a and 2a: r₁= 0.74; r₂= 1.28; copolymerization of 3a and 1a: r₁= 0.75 ± 0.04; r₂= 1.13 ± 0.01. In contrast to that, the copolymerization of the uncomplexed monomers 1–3 in organic medium (DMF/H₂O) leads to nearly ideal statistical copolymers in all cases. Received: 28 November 2000/Accepted: 12 January 2001     

Synthesis and gas permeability of poly(<Emphasis Type="Italic">p</Emphasis>-phenyleneethynylene)s having bulky alkoxy or alkyl groups

Dipropynylbenzene with branched alkoxy and alkyl groups [CH₃C≡CRC₆H₂RC≡CCH₃, R = 2-methylpropoxy (1a), 3-methylbutoxy (1b), 4-methylpentoxy (1c), cyclohexylmethoxy (1d), 2-ethylhexoxy (1e), 2-octoxy (1f), 2-ethylhexyl (1g), and 2-octyl (1h)] were polymerized with Mo(CO)₆ in the presence of 4-(trifluoromethyl)phenyl to afford poly(2,5-di(alkoxy or alkyl)-p-phenyleneethynylene)s (2a–h). Polymer 2a was insoluble in any solvents, but the other polymers (2b–h) were soluble in common organic solvents. The polymers with relatively long side chains (2e–h) had high molecular weight over 1.6 × 10⁴ and gave free-standing membranes by solution-casting method. The densities of membranes of 2e–h were 0.914–0.998, and their fractional-free volume values were relatively large (0.094–0.158). The oxygen permeability coefficients of membranes of 2e–h were 18.4, 12.7, 4.85, and 19.3 barrers, respectively. It was found that poly(p-phenyleneethynylene) with 2-octyl side groups, which have the branch at the nearest position from main chain, exhibited the highest gas permeability.     

Synthesis and characterization of poly(aryl ether ketone)s with fluorinated phenyl in the side chain

New bisphenol monomers, (4-fluorophenyl)hydroquinone (3b) and (3,4-difluoro phenyl)hydroquinone (3c), were synthesized in a two-step synthesis. Poly(aryl ether ketone)s (PAEKs) (4a–c) were derived from these fluorinated bisphenols and nonfluorinated bisphenol—phenylhydroquinone (3a) with 4,4′-diflourobenzophenone via a nucleophilic aromatic substitution polycondensation. The obtained polymers had inherent viscosities of 0.50–0.92 dL/g. Thermal analysis showed that the obtained PAEKs had excellent thermal properties, the glass transition temperatures ranged from 148 to 160 °C, and the temperatures at 5% weight loss (Td₅) were above 527 °C and the temperatures at 10% weight loss (Td₁₀) were above 544 °C in nitrogen. All the polymers showed excellent solubility and could dissolve in common organic solvents, such as DMSO, NMP, DMF, etc. So the films of them were easily cast from their solutions, which possessed good mechanical properties, with tensile strengths of 95.2–104.0 MPa, Young’s moduli of 2.68–3.06 GPa, and elongation at break of 15–32%. Furthermore, the prepared PAEKs displayed low dielectric constants (2.75–2.95 at 1 MHz) and hydrophobic character (contact angles for water: 83.9^o–98.4^o).     

Synthesis and surface properties of chemodegradable anionic surfactants: Diastereomeric (2-n-alkyl-1,3-dioxan-5-yl) sulfates with monovalent counter-ions

Sodium, potassium and ammonium cis- and trans-(2-n-alkyl-1,3-dioxan-5-yl) sulfates 6–8 (alkyl: n-C₉H₁₉, 6a–8a, and n-C₁₁H₂₃, 6b–8b) were synthesized in a reaction of aliphatic aldehydes 1a,b with glycerol 2 followed by separation in high yields of individual geometric isomers of cis-and trans-2-n-alkyl-5-hydroxy-1,3-dioxanes, cis-3a,b and trans-3a,b, followed by sulfation with sulfur trioxide-pyridine complex, and finally neutralization with NaOH, KOH, and NH₄OH, respectively. Physical data of the compounds and some surface properties of 2-n-nonyl derivatives, such as critical micelle concentration (CMC), effectiveness of aqueous surface tension reduction (Π_CMC), surface excess concentration Γ_CMC, and the surface area demand per molecule (A_CMC), were determined. It was shown that the surface activity of these compounds is influenced both by their geometric structure and by the monovalent counter-ion.     

Synthesis of poly(<Emphasis Type="Italic">p</Emphasis>-phenyleneethynylene)s bearing oligo-ethylene glycols and their gas permeation properties

1,4-Diiodobenzenes bearing oligo-ethylene glycols [IRC₆H₂IR, R = OCH₂CH₂OCH₃ (1a), O(CH₂CH₂O)₂CH₃ (1b), O(CH₂CH₂O)₃CH₃ (1c)] were polymerized with 1,4-diethynylbenzene in the presence of Pd/Cu catalyst to afford poly(p-phenyleneethynylene)s bearing oligo-ethylene glycols (2a–c), respectively. Polymer 2a was insoluble in any solvents, but the other polymers (2b, 2c) were soluble in CHCl₃. The weight-average molecular weights of 2b and 2c were 5.4 × 10⁴ and 9.6 × 10⁴, respectively, and they gave free-standing membranes by solution-casting method. The densities of membranes of 2b and 2c were 1.26 and 1.22 g/cm³, respectively, and their carbon dioxide permeability coefficients were 12.9 and 13.5 barrers, respectively. The CO₂/N₂ separation factor of membrane of 2b was as large as 33.7. Membrane of 3b, which contains triethylene glycols, exhibited higher CO₂ permselectivity, and the CO₂/N₂ separation factor was 50.0.     

Syntheses, Structures, and Luminescent Properties of Two Novel Coordination Polymers with Mixed Ligands

Two novel metal–organic coordination polymers {[Pb₂(MIP)₂(BDC)₂]·H₂O} _n 1 and [Cd(MIP)(NDC)] _n 2 [MIP = 2-(3-methoxyphenyl)-1H-imidazo [4,5-f] [1, 10] phenanthroline, BDC = terephthalic acid, NDC = naphthalene-1,4-dicarboxylic acid] were obtained from hydrothermal reaction and characterized by elemental analysis, thermogravimetric (TG) analysis, infrared spectrum (IR) and single-crystal X-ray diffraction. The coordination polymers crystallize in triclinic, space group P-1 with a = 1.0335(2), b = 1.4224(3), c = 1.8156(4) nm, β = 106.088(3)° for complex 1 and the complex 2 crystallizes in monoclinic, space group P2(1)/n with a = 1.2562(8), b = 1.4800(9), c = 1.3723(8) nm, β = 97.257(1)°, respectively. The metal ions Pb(II) are located in [:PbN2O4] pentagonal bipyramidal geometry in complex 1. The metal ions Cd(II) in complex 2 act as distorted octahedral geometry, being surrounded by four carboxylate oxygen atoms from three NDC ligands and two donor nitrogen atoms from one MIP molecule. Moreover, there are hydrogen bonds in the two complexes, and it is noteworthy that the existence of hydrogen bonds and π–π interactions reinforce the structural stability of the title complexes, which have been proved by TG analysis. The luminescent properties for the ligand MIP, NDC and complex 2 are also discussed in detail.     

Synthesis and characterization of new optically active poly(amide-imide)s containing 1,3,4-oxadiazole moiety in the main chain

Six new optically active poly(amide-imide)s were synthesized by poly condensation reaction of 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (8) with six chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenylphosphite (TPP), calcium chloride (CaCl₂), and pyridine. Chiral N,N′-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic)-bis-l-amino acids (3a–f) were obtained by the reaction of bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with two equimolar of l-alanine (2a), l-valine (2b), l-leucine (2c), l-isoleucine (2d), l-phenyl alanine (2e), and l-2-aminobutyric acid (2f) in acetic acid. The poly condensation reaction produced a series of novel poly(amide-imide)s (9a–f) in high yield and with inherent viscosities between 0.30 and 0.52 dL/g. The resulting polymers were characterized by elemental analysis, viscosity measurement, solubility testing, thermo-gravimetric analysis (TGA), ¹H-NMR, and FT-IR techniques.     

Microwave Dielectric Properties of (Mg1−xNix)2TiO4 (x=0.02–0.1) Ceramics

Low-loss ceramics in the system (Mg_1−xNi_x)₂TiO₄ (x=0.02–0.1) have been prepared using the conventional solid-state ceramic route. The formation of (Mg_1−xNi_x)₂TiO₄ (x=0.02–0.1) solid solutions was confirmed by the EDX analysis and the lattice parameters measured, which linearly varied from Mg₂TiO₄ (a=b=c=8.4410 Å) to (Mg_0.9Ni_0.1)₂TiO₄ (a=b=c=8.4335 Å). The X-ray diffraction analysis also confirmed the coexistence of a cubic-structured (Mg_1−xNi_x)₂TiO₄ and an ilmenite-structured second phase (Mg_1−xNi_x)TiO₃. By increasing x, not only could the Q×f of the (Mg_1−xNi_x)₂TiO₄ solid solution be considerably increased from 150,000 GHz at x=0 to a maximum 238,000 GHz at x=0.05, the highest ɛ_r∼16.43 could also be obtained simultaneously. This was mainly due to the uniform grain morphology and the highest density of the specimen. A good combination of microwave dielectric properties (ɛ_r∼16.43, Q×f∼238,000 GHz at 9.8 GHz, and τ_f∼−55 ppm/°C) can be achieved for a specimen using (Mg_0.95Ni_0.05)₂TiO₄ sintered at 1400°C for 4 h.     

Carbosilane Metallodendrimers with Cyclopentadienyldichlorotitanium(IV) End Groups

Dendritic polyols of the second and third generation 2G-OH₈ (1), 2G-OH₁₆ (2), and 3G-OH₁₆ (3) were prepared by hydroboration/oxidation of allyl-terminated carbosilane dendrimers and used as supports for the immobilization of cyclopentadienyltrichlorotitanium(IV) complexes via alcoholysis. The reaction of 1–3 with CpTiCl₃ gave metallodendrimers 2G-(OTiCpCl₂)₈ (4a), 2G-(OTiCpCl₂)₁₆ (5a), and 3G-(OTiCpCl₂)₁₆ (6a), respectively, whereas the reaction of 1 and 3 with CpSi^FTiCl₃ (CpSi^F = C₅H₄SiMe₂CH₂CH₂C₈F₁₇) yielded peripherally fluorinated metallodendrimers 2G-(OTiCpSi^FCl₂)₈ (4b) and 3G-(OTiCpSi^FCl₂)₁₆ (6b). All metallodendrimers were characterized by multinuclear NMR spectroscopy. The suggested structures were supported by comparison with model 1-propoxycomplexes 10a,b. To identify side products of the alcoholysis reaction, hydrolytic behavior of the starting trichloro complexes was studied both in solid state and in solution. The main products of hydrolysis in solution were identified as μ-oxocomplexes 8a,b whereas hydrolysis in solid state yielded mainly hydroxycomplexes 7a,b.     

Structures of the (4S, 14S)-4, 14-Dimethyl-3,6,9,12,15-pentaoxa-21-azabicyclo[15.3.1] heneicosa-1(21) 17,19-Triene-2,16-dione Complexes of R-and S-α-(1-Naphthyl)ethylammonium Perchlorate

Crystal data for the more stable (R) and less stable (S) 1:1 macrocycle-cation complexes are as follows: R cation: M_r = 625.08, orthorhombic P2₁2₁2₁, a = 8.47(1), b = 11.78(1), c = 31.19(6) A, V = 3112.0(123) ų, Z = 4, D_x = 1.333 kg m⁻³, λ(Mo Kα) = 0.71073 μ = 1.90 cm⁻¹, F(000) = 1320, T = 295 K, R = 0.17 for 1680 reflections. S Cation: M_r = 625.08, monoclinic, P2₁, a = 8.654(2), b = 11.954(3), c = 15.130(4) Å, β = 97.39(2)°, V = 1552.2(12) ų, Z = 2, D_x = 1.337 kg m⁻³, λ(Mo Kα) = 0.71073, μ = 1.91 cm⁻¹, F(000) = 660, T = 295K, R = 0.081 for 2751 unique reflections. Crystals of the complexes were prepared by the authors. The greater thermodynamic stability of the R cation complex is consistent with the observation that this cation experiences less steric interaction with the methyl substituent of the ligand than does the S cation.     

Synthesis and Gas Permeability of Novel Poly(diphenylacetylenes) Having Polyethylene Glycol Moieties

4-Trimethylsilyldiphenylacetylenes with methyl group or bromine atom (Me₃SiC₆H₄C≡CC₆H₄R, R = m-CH₃, p-CH₃, m-Br, p-Br, 1a–d, respectively) were polymerized with TaCl₅/ n-Bu₄Sn to afford poly(diphenylacetylene) derivatives (2a–d). The polymers (2a–d) had high molecular weight over 5×10⁵, and gave free-standing membranes by solution casting method. Chlorination of the obtained poly[1-(3-methylphenyl)-2-(4-trimethylsilyl)phenylacetylene] was carried out by using sulfuryl chloride, and then substitution of polyethylene glycol was performed to give poly(diphenylacetylene) possessing polyethylene glycol moieties. Its carbon dioxide permeability (P_{CO 2}) and permselectivity (P_{CO 2}/P_{N 2}) were 2,970 barrers and 9.0, respectively.