Synthesis of chiral helical poly[p-(oligopinanylsiloxanyl)phenylacetylene]s and enantioselective permeability of their membranes

To develop better polymeric materials for optical-resolution membranes, we synthesized nine chiral phenylacetylenes containing pinanyl groups. We used them to investigate the effects of chemical structures, including the number and position of the chiral groups in the monomers, on the induction of chirality in the main chain during polymerization and on the degree of enantioselectivity in the permeation of the polymeric membranes. The monomers included six new chiral p-(oligomethylpinanylsiloxanyl)phenylacetylenes. The homopolymerizations of these nine monomers with a Rh complex produced high-molecular-weight polymers (molecular weight = 10⁵–10⁶). Of the five polymers with a chiral pinanyl group at the 1-position of each oligosiloxanyl group, all except for two polymers showed high molar ellipticity in the main-chain region in the circular dichroism spectra. This finding indicated that these polymers had a chiral helical main chain. The membranes fabricated from all the polymers synthesized in this study were high-quality, except for two polymers. All these membranes showed enantioselective permeabilities for two amino acids and an alcohol. The membranes from the polymers with a chiral helical backbone, a high content of pinanyl groups, no oligodimethylsiloxane moieties, or a combination of these showed good enantioselectivities (= 1.7–640) in permeation. We propose that the sense of the main-chain helicity determined the selectivity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4502–4517, 2004     

The synthesis of poly(phenylacetylene)s with bulky chiral silyl groups and the thermal stability of their helical conformation

The polymerization of (−)‐p‐[(tert‐butylmethylphenyl)silyl]phenylacetylene (t‐BuMePhSi*PA) and (+)‐p‐[{methyl(α‐naphthyl)phenyl}silyl]phenylacetylene (MeNpPhSi*PA) with the [(nbd)RhCl]₂ Et₃N catalyst yielded polymers with very high molecular weights over 2 × 10⁶ in high yields. The optical rotations of the formed poly(t‐BuMePhSi*PA) and poly(MeNpPhSi*PA) were as high as −356 and −150° (c = 0.11 g/dL in CHCl₃), respectively. The circular dichroism (CD) spectrum of poly(t‐BuMePhSi*PA) in CHCl₃ exhibited very large molar ellipticities ([θ]) in the UV region: [θ]_max = 9.2 × 10⁴ ° · cm² · dmol⁻¹ at 330 nm and −8.0 × 10⁴ ° · cm² · dmol⁻¹ at 370 nm. The [θ]_max values of poly(MeNpPhSi*PA) were also fairly large: [θ]_max = 7.1 × 10⁴ ° · cm² · dmol⁻¹ at 330 nm and −5.3 × 10⁴ ° · cm² · dmol⁻¹ at 370 nm. The optical rotations of poly(t‐BuMePhSi*PA) and poly(MeNpPhSi*PA), measured in tetrahydrofuran, chloroform, and toluene solutions, were hardly dependent on temperature in the range 22–65 °C. The CD effects of these polymers hardly changed in the temperature range 28–80 °C, either. These results indicate that the helical structures of these polymers are thermally appreciably stable. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 71–77, 2001     

Gas permeation properties of poly(silamine) membrane

The gas permeation characteristics of poly(silamine) membrane, which consists of alternating 3,3-dimethyl-3-silapentane and N,N′-diethylethylenediamine units in the main chain, were investigated. Though poly(silamine) shows high flexibility (glass transition temperature of −88°C), the gas permeabilities were much lower than those of other rubbery polymers such as poly(dimethylsiloxane) and natural rubber. The activation energies of diffusion in poly(silamine) were much higher than that of natural rubber. On the basis of these results, we propose a model such that the interaction between the Si atom and gas molecules (O₂ and N₂) prevents the free diffusion of the gas molecule in the poly(silamine) membrane. © 1997 John Wiley & Sons, Ltd.     

Degradation behavior of stereoregular cis–transoidal poly(phenylacetylene)s

The stability of poly(phenylacetylene)s in solution was systematically studied. Cis–transoidal poly(phenylacetylene) prepared with a Rh catalyst readily underwent autoxidative degradation into oligomers, whereas a W‐based polymer with a trans‐rich geometrical structure degraded slowly under similar conditions. The degradation of W‐based poly(phenylacetylene) was independent of the solvents, whereas the degradation of the cis–transoidal material strongly depended on the solvents, and very rapid degradation was observed in toluene and CHCl₃. A reduction in the degradation rate in the absence of oxygen and the appearance of carbonyl groups in an IR spectrum and aldehyde protons in a ¹H NMR spectrum of the resulting oligomers indicated the direct participation of oxygen in the degradation where light was supposed to assist the degradation by producing radicals on the main chain. The cis content of cis–transoidal poly(phenylacetylene) was unchanged during the degradation, unlike for the acid‐catalyzed decomposition, in which the cis content decreased linearly as the molecular weight decreased. Ring‐substituted poly(phenylacetylene)s degraded slowly compared with poly(phenylacetylene), regardless of the kind of substituent, which suggests that steric factors affected the degradation rate. The use of radical scavengers such as 2,2,6,6‐tetramethylpiperidine‐1‐oxyl and diphenylpicrylhydrazil suppressed the decomposition. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3130–3136, 2001     

Influence of ortho‐substituents on the synthesis and properties of poly(phenylacetylene)s

The phenylacetylene derivatives (4‐decyloxyphenyl)acetylene ( M1 ), (4‐decyloxy‐2‐methylphenyl)acetylene ( M2 ), and (4‐decyloxy‐2,6‐dimethylphenyl)acetylene ( M3 ) were polymerized by the well‐defined Schrock‐type initiator Mo[N‐2,6‐i‐Pr₂C₆H₃)(CHCMe₂Ph)[OCMe(CF₃)₂]₂ ( I1 ) and by the ill‐defined quaternary system MoOCl₄–n‐Bu₄Sn–EtOH–quinuclidine (1:1:2:1) ( I2 ). Comparison of the compatibility of the initiators with the different monomers revealed a correlation of the size of the ortho‐substituents and the polymerizability of the monomers. M1 and M2 readily polymerized employing I1 , but conversion of the sterically demanding monomer M3 remained incomplete. However, the use of I2 led to high monomer conversions and polymer yields only in case of M2 and M3 . The steric bulkiness of the ortho‐substituents also decisively affected the maximum effective conjugation length (N_eff) of the polymers and hence their absorption maximum (λ_max) as well as their solution stability as shown by UV–vis and GPC studies, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4466–4477, 2004     

Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups

Poly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′-dichlorodiphenylsulfone ( 1 ) and sodium 5,5′-sulfonylbis (2-chlorobenzenesulfonate) ( 2 ) with bisphenols ( 3 ) in the presence of potassium carbonate in N,N-dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m-cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.     

Morphological characterization of poly(phenylacetylene) nanospheres prepared by homogeneous and heterogeneous catalysis

Scanning electron microscopy characterization of the materials obtained by homogeneous and heterogeneous catalytic polymerization of phenylacetylene is described. The catalysts used are β‐dioxygenato rhodium(I) complexes. The effects of the reaction medium, presence of a cocatalyst and the type of catalysis (homogeneous or heterogeneous) on the morphology of the polymers obtained have been studied and discussed. Using a supported complex at 0 °C, nanoparticles with a diameter distribution as narrow as 30 to 70 nm were obtained. Polymer nanopowders were found to be unaffected by ageing. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and properties of sulfonated poly(arylene ether)s containing azole groups

Random and multiblock sulfonated poly(arylene ether sulfone)s (SPEs) containing various azole groups such as oxadiazole and triazole were synthesized and characterized for fuel cell application. Successful preparation of SPE membranes depended on the structure of azole groups, which affected solubility of precursors and the resulting SPEs. Although oxadiazole groups were incorporated into hydrophobic component, they were found to be hydrophilic to give higher proton conductivity. Introduction of oxadiazole groups into random SPE gave comparable proton conductivity to that of Nafion NRE at >60% relative humidity at 80 °C. Block copolymer structure further increased the proton diffusion coefficient without increasing ion exchange capacity. Hydrolytic and oxidative stability of the SPE membranes was affected by both hydrophilic and hydrophobic components. Oxadiazole groups gave negative impact on hydrolytic and mechanical stability to the SPE membranes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of hydrophilicity-controlled poly(arylene ether sulfone) copolymers with phenolphthalein-based carboxylic acid groups for separation membrane applications

Abstract

Hydrophilicity-controlled poly(arylene ether sulfone) copolymers with phenolphthalein-based carboxylic acid groups (PES-COOH-X) were synthesized via direct copolymerization by adjusting the feed molar ratio. The chemical structures of the obtained copolymers were confirmed by ¹H nuclear magnetic resonance (NMR) spectroscopy. The copolymers showed good solubility in common aprotic solvents and exhibited excellent mechanical properties. The water contact angles of the obtained copolymers could be reduced by approximately 52% from 92.1° to 44.2° with increasing content of phenolphthalein-derived monomer, 2-[bis(4-hydroxyphenyl)methyl] benzoic acid (PPH-COOH), in the feed molar ratio. A series of PES-COOH-X membranes was prepared via a conventional immersion precipitation phase inversion method. The effects of the monomer feed molar ratio on the morphology, hydrophilicity, pure water flux, and water uptake of the prepared membranes were investigated. The results showed that the pure water flux of the PES-COOH-X membranes was significantly enhanced by almost a factor of two as compared to the pristine PES membrane. From the water contact angle data, it was identified that the hydrophilicity of the membranes was increased rapidly with increasing PPH-COOH content in the membranes. These hydrophilicity-controlled poly(arylene ether sulfone) copolymers may be considered as good candidates for separation membrane materials.     

Synthesis and characterization of poly(arylene ether ketone)s bearing pendant sulfonic acid groups for proton exchange membrane materials

A bisphenol monomer (2,5‐dimethoxy)phenylhydroquinone was prepared and further polymerized to obtain poly(arylene ether ketone) copolymers containing methoxy groups. After demethylation and sulfobutylation, a series of novel poly(arylene ether ketone)s bearing pendant sulfonic acid group (SPAEKs) with different sulfonation content were obtained. The chemical structures of all the copolymers were analyzed by ¹H NMR and ¹³C NMR spectra. Flexible and tough membranes with reasonably good mechanical properties were prepared. The resulting side‐chain‐type SPAEK membranes showed good dimensional stability, and their water uptake and swelling ratio were lower than those of conventional main‐chain‐type SPAEK membranes with similar ion exchange capacity. Proton conductivities of these side‐chain‐type sulfonated copolymers were higher than 0.01 S/cm and increased gradually with increasing temperature. Their methanol permeability values were in the range of 1.97 × 10^?7–5.81 × 10^?7 cm²/s, which were much lower than that of Nafion 117. A combination of suitable proton conductivities, low water uptake, low swelling ratio, and high methanol resistance for these side‐chain‐type SPAEK films indicated that they may be good candidate material for proton exchange membrane in fuel cell applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of photoreactive poly(ether ether ketone)s containing alkyl groups

Poly(ether ether ketone)s containing alkyl groups were prepared by nucleophilic substitution reaction of alkyl-substituted difluoro diaryl ethers with hydroquinone or by electrophilic substitution reaction of alkyl-substituted diaryl ether with 4,4′-oxydibenzoic acid in PPMA. Polycondensations proceeded smoothly and produced polymers having inherent viscosities up to 0.5-–1.6 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, and chloroform at room temperature. Thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight loses of the polymers were observed in the range above 450°C in nitrogen atmosphere. The glass transition temperatures of the polymers ranged from 128 to 146°C. Furthermore, Polymer 3b functioned as a photosensitive resist of negative type for UV radiation. The resist had a sensitivity of 42 mJ/cm² and a contrast of 2.5, when it was postbaked at 100°C for 10 min, followed by development with THF/acetone at room temperature. © 1996 John Wiley & Sons, Inc.     

Synthesis and properties of poly(silylenephenylenevinylene)s

Polymerization of o-, m-, and p-(dimethylsilyl)phenylacetylene by chloroplatinic acid-catalyzed hydrosilylation gave the corresponding poly(dimethylsilylenephenylenevinylene)s. The monomer reactivity and polymer structure were very much dependent upon the substituent position. Interesting optical behavior and thermal properties were observed which suggested the polymers to be useful as preceramic materials. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2263–2273, 1999     

Synthesis and properties of a poly(diphenylacetylene) containing carbazolyl groups

1-(p-N-Carbazolylphenyl)-2-phenylacetylene (p-CzDPA) was polymerized by TaCl₅–co-catalyst systems (cocatalysts: n-Bu₁Sn, Et₃SiH, and 9BBN) to produce acetone-insoluble polymers in about 60-70% yields. Poly(p-CzDPA) was a yellowish-orange solid, most part of which was soluble in toluene, chloroform, etc., and its weight-average molecular weights were around 4×10⁵. This polymer formed a tough film by solution casting, and was thermally very stable (the onset temperature of weight loss in TGA in air 470°C). The oxygen per-meability coefficient of the polymer at 25°C was lower than two barrers. The present polymer showed photoconductivity and redox activity. © 1995 John Wiley & Sons, Inc.     

Recyclable helical poly(phenylacetylene)‐supported catalyst for asymmetric aldol reaction in aqueous media

A novel one‐handed helical poly(phenylacetylene) bearing L‐hydroxyproline pendants (poly(PA‐P)) was synthesized as an eco‐friendly polymer‐supported catalyst for asymmetric reactions. The helical poly(PA‐P) catalyzed the asymmetric aldol reactions of cyclohexanone with p‐nitrobenzaldehyde, and showed good recyclability and higher enantiomeric excess (ee) in aqueous medias than that in organic medias. The one‐handed helicity of poly(PA‐P) was clearly affected by the water content in the aqueous media. The helical poly(PA‐P) showed the higher enantioselectivity (ee = 99%) than its monomer PA‐P (ee = 54%) in THF/H₂O (H₂O vol % = 25.0 vol %). After the one‐handed helical structure of poly(PA‐P) was destroyed by grinding treatment, the ee of the reaction clearly decreased from 99 to 49%. These indicate that the one‐handed helical structure of poly(PA‐P) played an important role in the high enantioselectivity of the asymmetric aldol reactions in the aqueous media. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1024–1031     

Synthesis and properties of various poly(diarylacetylenes) containing siloxy and hydroxy groups

Diarylacetylene monomers ( 1b ? f) containing siloxy and either naphthyl, fluorenyl, or biphenyl groups were polymerized with TaCl₅–n‐Bu₄Sn catalyst, and 1b , 1c , and 1f provided high molecular weight polymers. Free‐standing membranes of polymers 2b , 2c , and 2f were fabricated by casting from toluene solution. Desilylation of these polymer membranes was carried out with trifluoroacetic acid to afford poly (diarylacetylenes) membranes having hydroxy groups ( 3b and 3c ). According to thermogravimetric analysis (TGA), both siloxy‐containing and hydroxy‐containing polymers exhibited high thermal stability, and the onset temperatures of weight loss in air were ～370 °C and ～430 °C, respectively. The CO₂ permeability coefficients of these membranes were in the range of 65–640 barrers. The points of 3b and 3c in the PCO₂ versus PCO₂/PCH₄ plot were located above Robeson's upper bound. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4487–4495, 2007     

Gas transport in surface grafted polypropylene films with poly(acrylic acid) chains

This work describes the grafting reaction of poly(acrylic acid) (PA) onto the surface of polypropylene (PP) films carried out with ultraviolet radiation, using benzophenone as photoinitiator and water as solvent. By increasing the reaction time, graft percentages of 3.5, 6.5, 12.9, 19.8, 29.4, and 36.0% were obtained. Micrographs of the modified films show that grafting exclusively occurs on the PP films surface. The values of the permeability coefficient of oxygen, nitrogen, carbon dioxide, carbon monoxide, argon, methane, ethane, ethylene, and propane across the grafted films undergo a sharp drop. The interpretation of the permeation results suggest that radicals created in the tertiary carbons of the grafted chains by effect of UV light or by chain transfer reactions may highly crosslink the PA grafted layer. A rigid layer involving both strong hydrogen bonding and chains crosslinking is formed at grafting percentages of 3.5% that strongly hinders gas permeation across that layer. Destruction of hydrogen bonding by partially replacing protons of acrylic acid residues by sodium/silver cations increases the permeability of the surface grafted films. Finally, the films permselectivity is hardly affected by the grafted layer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2421–2431, 2007     

Trimethylsilyl-group containing polyphenylacetylenes for oxygen and ethanol permselective membranes

Phenylacetylenes having one or two trimethylsilyl groups at their benzene ring were synthesized, and polymerized by [Rh(cyclooctadiene) (PPh₃)₂]PF₆, [Rh(norbornadiene)Cl]₂, or WCl₆ to afford high molecular-weight polymers in high yields. These poly(phenylacetylene)s were soluble in many kinds of solvents and were fabricated to tough membranes by the solvent casting method. The oxygen permselectivities of these membranes were very good. The oxygen permeability coefficients (P_o2) and oxygen separation factors (α = P_o2/P_N2) of poly[2,4-(o,p)-bis(trimethylsilyl)phenylacetylene] [poly ( o-1-p-1 )] and poly[(4(p)-trimethylsilyl)phenylacetylene] [poly( p-1 )] membranes were 4.73 × 10^?8 cc(STP) cm/cm² s cmHg and 2.65, and 1.52 × 10^?8 cc(STP) cm/cm² s cmHg and 3.39, respectively. In the case of poly( o-1-p-1 ), P_o2 was comparable to that of polydimethylsiloxane (PDMS) and α was higher than that of PDMS. However, the P_o2 value reduced to 48% of its initial value in about 1 year. In the case of poly( p-1 ), the P_o2 value did not change in about 1 year. Ethanol permeated preferentially through these membranes (α^EtOH > 1) in pervaporation of aqueous ethanol solution, whereas poly(phenylacetylene) [poly( PhA )] showed water permselectivity (α^EtOH < 1). These favorable effects of trimethylsilyl groups on the oxygen and ethanol permselectivities were discussed on the basis of comparison with those of poly( PhA ), other poly(substituted phenyl-acetylene)s, and trimethylsilyl-group containing polystyrenes. © 1994 John Wiley & Sons, Inc.     

Self-Crosslinkable poly(arylene ether)s containing pendent phenylenetriazene groups

Self-crosslinkable poly(arylene ether)s 6 , and 8 , containing pendent triazene groups were prepared by nucleophilic substitution reaction of poly(arylene ether)s 5 , and 7 , respectively, with 1-[4-(4-hydroxyphenoxy)phenylene]triazenes, 4 , in the presence of potassium carbonate in N,N-dimethylacetamide. A series of triazenes 4 containing various substituents have been synthesized. Self-crosslinkable polymer 6e containing phenyl-substituted triazene pendants can be crosslinked at 215°C, which is about 40°C lower than the glass transition temperature of the virgin base polymer 5 . The degree of crosslinking can be tailored by varying the concentration of the pendent phenylenetriazene groups in the polymer. After curing, the flexible polymer films (ca. 10 μm thick) exhibit high gel contents, increased glass transition temperatures, improved resistance to organic solvents, and little change in dielectric constant and thermal stability. These self-crosslinkable poly(arylene ether)s are potential candidates for electronic applications. © 1994 John Wiley & Sons, Inc.     

Synthesis and characterization of poly(amide sulfonamide)s (PASAs)

New diamino monomers IIa – IIg were synthesized in a two-step reaction sequence starting from p-acetamidobenzenesulfonyl chloride. Solution polymerization of these monomers in DMAC with terephthaloyl or isophthaloyl chloride resulted in the formation of a series of 14 poly(amide sulfonamide)s (PASAs) in excellent yield (> 95%). The polymers have in-trinsic viscosities of 0.32–1.11 dL g^?1. Except for polymers IIIa ? p and IIId - p , all other PASAs were readily soluble in aprotic polar solvents including DMAC, DMF, and DMSO. Thermogravimetric analyses of the polymers showed moderate thermal stability with 10% weight loss being recorded in the range of 325–408°C. In addition, these polymers exhibit moderate chemical stabilities toward alkali, acidic, and chromic acid solution. © 1995 John Wiley & Sons, Inc.     

Synthesis and properties of sulfonated poly(arylene ether) containing tetraphenylmethane moieties for proton‐exchange membrane

A novel sulfonated poly(arylene ether) containing tetraphenylmethane moieties was successfully synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place only at the para position on the pendant phenyl rings because of the specially designed parent polymer. The sulfonation degree can be easily controlled by using different ratios of sulfonation agent to polymer repeating unit. The position and degree of sulfonation were characterized by ¹H NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N′‐dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton's reagent test revealed that the membrane exhibited superior stability to oxidation. The proton conductivities of the films were determined to be equivalent with Nafion® 117 under same conditions. The new polymer with sulfonic acid function on pendent phenyl rings can be potentially used as a proton‐exchange membrane for polymer electrolyte membrane fuel cell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6411–6418, 2005