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Two novel types of degradable acetal-linkage-containing epoxy resins were synthesized through the addition reaction of 2,2-bis(4-hydroxycyclohexyl)propane (HBA) or 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane (HOBA) with cyclohexane dimethanol vinyl glycidyl ether (CHDMVG). The thermal decomposition temperatures (Td) of the cured HBA–CHDMVG (283 °C) and HOBA–CHDMVG (319 °C) epoxy resins indicated that they were more thermally stable than several previously reported acetal-linkage-containing epoxy resins. The Charpy impact test results demonstrated that the toughnesses of the HOBA–CHDMVG-based epoxy resin sheets and HOBA–CHDMVG-based carbon fiber-reinforced plastics (CFRPs) were higher than those of conventional bisphenol-A-based epoxy resin sheets and CFRPs. The HOBA–CHDMVG-based epoxy resin sheets were completely decomposed via hydrolysis under acidic conditions, and the hydrolysis products were soluble in a tetrahydrofuran–H2O mixed solvent. Furthermore, the carbon fibers of the HOBA–CHDMVG-based CFRPs were recovered via the decomposition of the matrix epoxy resin. In contrast, when H2O was the only solvent for the acid treatment, the HOBA–CHDMVG-based epoxy resin sheets and CFRPs did not undergo any changes. Therefore, we developed novel degradable epoxy resins, which easily decomposed in the presence of organic solvents, were stable in the absence of organic solvents and exhibited high thermal stability and remarkable toughness. Novel alcohol-derived degradable acetal-linkage-containing epoxy resins HBA–CHDMVG and HOBA–CHDMVG were synthesized. The thermal decomposition temperature of HOBA–CHDMVG was higher than 300 °C; moreover, HOBA–CHDMVG exhibited excellent Charpy impact strength. The cured HOBA–CHDMVG was completely decomposed during the hydrolysis reaction under acidic conditions, and the reaction products were soluble in a tetrahydrofuran/H2O mixed solvent. Furthermore, the carbon fibers in the carbon-fiber-reinforced plastic with a HOBA–CHDMVG matrix were recovered via the complete decomposition of HOBA–CHDMVG.

Metathesis copolymerization of 1-(p-trimethylsilyl)phenyl-1-propyne with diphenylacetylenes was achieved and the gas permeability of polymer membranes was improved by the incorporation of 20% phenylpropyne unit.

Efficient gas-separation systems comprising gas-permeable membranes are important for energy conservation in various industrial applications. Herein, high-molecular-weight copolymers (2ab and 2ac) were synthesized in good yields by the copolymerization of 1-(p-trimethylsilyl)phenyl-2-(p-trimethylsilyl)phenylacetylene (1a) with 1-phenyl-2-(p-tert-butyl)phenylacetylene (1b) and 1-phenyl-2-(p-trimethylsilyl)phenylacetylene (1c) in various monomer feed ratios using TaCl5–n-Bu4Sn. Tough membranes were obtained by solution casting. The copolymers exhibited very high gas permeabilities (PO2: 1700–3400 barrers). Desilylation of 2ac membranes decreased the gas permeability, but desilylation of 2ab membranes resulted in a significant increase in the gas permeability. The highest oxygen permeability coefficient obtained was 9300 barrers, which was comparable to that of poly(1-trimethylsilyl-1-propyne), a polymer known to have the highest gas permeability.

The metathesis polymerization of monomers containing two diphenylacetylene units [Me3SiC6H4CCC6H4CCR; R = o-SiMe3C6H4 (1a), o,o-(SiMe3)2C6H3 (1b), o,o,p-(SiMe3)3C6H2 (1c), and o-CF3C6H4 (1d)] was performed using TaCl5/n-Bu4Sn. The polymerization of 1a–c containing SiMe3 group at the ortho position of a benzene ring afforded solvent-soluble products (2a–c) without crosslinking since the reaction of one acetylene was suppressed by steric hindrance. In contrast, the polymerization of 1d containing CF3 group afforded a solvent-insoluble product (2d). Polymers 2a–c exhibited similar thermal stability with a high decomposition temperature (T0 = 380 °C). Upon excitation with 400 nm light, 2a–c exhibited emissions (530 nm) at a longer wavelength than that of poly(diphenylacetylene) without a phenylacetylene on the side group. In addition, 2b and 2c exhibited intense fluorescence. The oxygen permeability coefficients of 2a–c were 54.3, 268, and 375 barrer, respectively. Gas diffusivity and solubility increased with increasing number of SiMe3 groups in the repeating unit.

The development of highly gas-permeable membranes is required for gas separation applications. In this study, 1-(

The interfacial adhesion property of telechelic polypropylenes (PPs) imparted by the controlled thermal degradation of commercial PPs and the subsequent end group transformation was investigated to determine the potential of telechelic PP as a candidate for PP matrix resin-coupling agents for CF-reinforced PP composites. In particular, we studied the interfacial shear strength (IFSS) between telechelic PPs with terminal double bonds or terminal hydroxyl groups and CFs for the first time. The hydroxyl-terminated PP showed higher IFSS than that of commercial PPs. The hydroxyl groups of hydroxyl-terminated PP interacted with CF surfaces via hydrogen bonding, which led to higher interfacial adhesion. Furthermore, hydroxyl-terminated PP homopolymer (hPP-OH_27k) was mixed with conventional isotactic polypropylene (iPP), and used as a coupling agent. The IFSS of the iPP/hPP-OH_27k blend was comparable to that of iPP/maleic anhydride-grafted polypropylene (MAPP), which is typically used as a coupling agent of the PP matrix. The iPP/hPP-OH_27k blend showed higher crystallinity and higher tensile strength than the iPP/MAPP blend based on the DSC measurements and tensile tests. These results indicated that hPP-OH_27k functions as a novel coupling agent of the PP matrix. The interfacial adhesion between olefinic double bond- or hydroxyl-terminated telechelic polypropylenes (PPs) and carbon fibers was studied to determine the potential of the telechelic PPs as a candidate for PP matrix resin-coupling agents for carbon fiber-reinforced PP composites. The hydroxyl-terminated PP showed higher interfacial shear strength than that of commercial PP and olefinic double bond-terminated PP. The hydroxyl-terminated PP could be used as a novel coupling agent of the PP matrix.

Star-shaped cyclopolymers were first synthesized on the basis of living cationic cyclopolymerization of divinyl ethers bearing a variety of bulky substituents, including cyclohexene, norbornene, norbornane, cyclic acetal, and adamantane groups. All the obtained cyclopolymers exhibited a high degree of cyclization, as high as ~97%, judging from the contents of residual pendant vinyl ether double bonds in the polymers. The glass transition temperatures (Tgs) of both the linear and star-shaped cyclopolymers were in the range of 145−229 °C depending on the pendant substituents. Methacrylate-terminated end-functionalized star-shaped cyclopolymers were synthesized by the functionalized initiator-based living cationic cyclopolymerization of divinyl ethers. The subsequent cross-linked core formation occurred via the reaction of the growing tail termini, whereas the methacrylate head terminals remained intact. The obtained end-functionalized star-shaped cyclopolymers were subjected to a thermal cross-linking reaction to yield star-shaped cyclopolymer networks with film-forming ability. Controlled cationic cyclopolymerizations of divinyl ethers with cyclohexene, norbornene, norbornane, cyclic acetal, or adamantane moiety were carried out. High-molecular-weight star-shaped cyclopolymers were synthesized by the reaction of the formed living cyclopolymers with a small amount of divinyl ether crosslinking agent. Glass transition temperatures (Tg’s) of both the cyclopolymers and star-shaped cyclopolymers were as high as 145−229 oC. Methacrylate-terminated end-functionalized star-shaped cyclopolymers were synthesized by the functionalized initiator-based living cationic cyclopolymerization of divinyl ethers followed by the chain linking reactions among the formed living cyclopolymers with divinyl ether crosslinker. The obtained end-functionalized star-shaped cyclopolymers were subjected to thermal crosslinking reaction to give star-shaped cyclopolymer networks with film-forming ability.

New epoxy resins containing degradable acetal linkages were synthesized by the addition reaction of bisphenol-A (BA) and epoxy-functionalized vinyl ethers containing hydrophilic oxyethylene chains, 2-(vinyloxy)ethyl glycidyl ether (VEGE) and 2-[2-(vinyloxy)ethoxy]ethyl glycidyl ether (VEEGE). Carbon fibers were applied with the obtained degradable epoxy resin-based sizing agents (designated as BA-VEGE and BA-VEEGE) in ordinary (1.4 ~ 2.2 wt%) or excess (6.4 ~ 13.4 wt%) amounts. Interfacial adhesion between the carbon fibers applied with the degradable epoxy resin-based sizing agents and matrix resins (bisphenol-A-type epoxy resin) was evaluated by the microdroplet method. Carbon fibers with both degradable epoxy resins as a sizing agent showed improved adhesive properties compared with the desized carbon fibers. Using the degradable sizing agent-applied carbon fibers, carbon fiber-reinforced plastics (CFRPs) were prepared by laminating prepreg sheets and heating them under pressure. The tensile properties of the CFRPs with [0]50 lay-up did not depend on the structure of the sizing agents, but the tensile strength decreased as the amount of sizing agent used increased. On the other hand, the tensile properties of the CFRPs with [0/90]12S lay-up were not dependent on the structure or volume of sizing agents used. The impact toughness of the CFRPs was evaluated by the charpy impact test. When an ordinary volume of sizing agent was applied, the CFRPs with degradable epoxy resin-based sizing agents exhibited higher levels of impact strength than the commercial sizing agent-based CFRPs. However, applying an excessive volume of sizing agent to carbon fibers led to a decline in impact strength. The degradation reaction was conducted under acidic conditions by the treatment of HCl at room temperature or 70 °C. CFRPs with degradable epoxy resins as sizing agents in ordinary volumes were barely decomposed due to insufficient degradable regions in the CFRP components. However, the CFRPs applied with excess degradable sizing agents decomposed and carbon fibers were recovered. The new epoxy resins containing degradable acetal linkages were synthesized and used as sizing agents for carbon fibers. Using the degradable sizing agent-applied carbon fibers, the carbon fiber-reinforced plastics (CFRPs) were prepared via laminating prepreg sheets and heating them under pressure. The mechanical properties of the obtained CFRPs were comparable with those of the conventional CFRPs. With the treatment of acidic conditions, the CFRPs with the degradable sizing agents on carbon fiber surface were decomposed and the carbon fibers could be recovered.

In this study, the effect of the addition of metal particles on the gelation properties of poly[1-(3,4-dimethoxyphenyl)-2-(4-trimethylsilylphenyl)acetylene] [poly(DMOTMSDPA)] and poly[1-phenyl-2-(4-trimethylsilylphenyl)acetylene] [poly(TMSDPA)] was examined. The addition of TaCl5, NbCl5, and MoCl5 to poly(DMOTMSDPA) and poly(TMSDPA) solutions afforded gels. However, the addition of Ta(OCH3)5 and Mo(OCH3)5 did not induce gelation. Lewis acids such as TaCl5, NbCl5, and MoCl5 can coordinate with the π-electrons from the polyacetylene backbone and lone pair of the methoxy groups. Mixed matrix membranes (MMMs) composed of poly(DMOTMSDPA) and these metal chlorides were fabricated by varying the amount of metal chloride. The metal chloride particles were uniformly dispersed in poly(DMOTMSDPA) because the polymer chains could interact with the metal chloride particles. The oxygen permeability of the MMMs composed of poly(DMOTMSDPA) was greater than that of pure poly(DMOTMSDPA). With the addition of 20 mol% of TaCl5, the oxygen permeability increased. In addition, the gas permeability of poly(TMSDPA) was increased by the addition of TaCl5. On the other hand, the gas selectivity values of MMMs were 1.8–3.1, suggesting that MMMs do not contain non-selective defects such as pinholes and interfacial voids in the matrix.

Imidazolium-based diphenylacetylene copolymers were developed to achieve excellent carbon dioxide/nitrogen and oxygen/nitrogen gas separation. A polymer with bromoethoxy groups (CoTMS-BrEtO) was first synthesized through copolymerization of the corresponding monomers. The polymer with pendant imidazolium bromine salts (CoTMS-IMBr) was then obtained by substitution with 1-methylimidazole. A polymer with bulky counter anions (CoTMS-IMTf2N) was also prepared by anion exchange of the Br− anions in CoTMS-IMBr with Tf2N− anions. All the membranes exhibited good thermal stabilities, and the incorporation of imidazolium salts enhanced the gas separation performance. CoTMS-IMBr exhibited good carbon dioxide/nitrogen and oxygen/nitrogen selectivities [e.g., CoTMS-IMBr(1:4) αCO2/N2 = 63, αO2/N2 = 9.2], and the oxygen separation results exceeded the Robeson 2008 upper bound values. Of the two types of imidazolium-based copolymers, CoTMS-IMTf2N exhibited the higher permeability.

Four types of diphenylacetylene monomers [Me3SiC6H4C CC6H4R; R = OCH2CH2Br (M1), CH2CH3 (M2), OCH CH2 (M3), and CH CH2 (M4)] were synthesized to facilitate the crosslinking of poly(diphenylacetylene)s via post-polymerization modification. Metathesis polymerizations of M1 and M2 using TaCl5/n-Bu4Sn afforded corresponding high-molecular-weight poly(diphenylacetylene)s (P1 and P2; Mw = 1,370,000 and 1,410,000, respectively). However, the polymerization of M3 and M4 afforded a low-molecular-weight polymer (Mw of 6290) and an insoluble product, respectively. The elimination reaction of the side groups in P1 using t-BuOK yielded poly(diphenylacetylene) with vinyl-ether side groups (P1–V). A crosslinked poly(diphenylacetylene) (C–P1–V) was subsequently synthesized via cationic polymerization of the vinyl-ether side groups of P1–V using BF3·OEt2. Another crosslinked poly(diphenylacetylene) (C–P2–Br) was synthesized via radical coupling of the side chains in P2 using N-Bromosuccinimide/benzoyl peroxide. The crosslinked poly(diphenylacetylene)s exhibited relatively low gas permeability among the poly(diphenylacetylene) derivatives, with oxygen permeability coefficients of 35 and 6.8 barrer for C–P1–V and C–P2–Br, respectively.

Achiral poly(diphenylacetylene)s (PDPAs: pMe3, pEt3, piPr3, pMe2O1, pMe2OD1, and mMe3) with different alkyl side chains at the para or meta position of the side phenyl ring were prepared to examine achiral-to-chiral transformations upon thermal annealing in a chiral solvent. All the para-substituted PDPAs showed significant circular dichroism (CD) enhancement upon annealing, whereas the meta-substituted polymer, mMe3, was inert to the same treatment. To investigate the kinetics, the asymmetric conformational change was monitored by observing the changes in the magnitude of circular polarization (gCD) or optical rotation. PDPAs with bulkier, round-shaped side groups (pEt3 and piPr3) had greater gCD values at equilibrium than pMe3 with a smaller side group. Moreover, the activation energy for the forward reaction (Eaf) was lower in the bulkier polymers than in pMe3 owing to enhanced miscibility with the chiral solvent. Similarly, the long alkyl chains of pMe2O1 and pMe2OD1 acted as internal plasticizers to ...

Recyclable carbon fiber-reinforced plastics (CFRPs) with controlled degradability and stability were developed by adding bisphenol A (BA)-type epoxy resins containing acid-degradable acetal linkages (BA-CHDMVG) to the matrix resins of CFRPs. BA-CHDMVG was synthesized by the reaction of the hydroxyl groups of BA with vinyl ether containing a glycidyl group (cyclohexane dimethanol vinyl glycidyl ether (CHDMVG)) and added to conventional BA-type epoxy resins (jER828 and jER1001). The acetal linkage-containing CFRPs (BA-CHDMVG-based CFRPs) were prepared using a mixture of these epoxy resins as the matrix. The obtained CFRPs exhibited almost the same tensile and thermal properties as those of the conventional BA-based CFRP (BA-based CFRP). One of the BA-CHDMVG-based CFRPs, (BA-CHDMVG)40-(jER1001)60-based CFRP (content in the matrix resin: BA-CHDMVG, 40 wt%; jER1001, 60 wt%), underwent smooth degradation through hydrolysis of the acetal linkages incorporated into the matrix resin upon treatment with 0.1 mol l−1 hydrochloric acid in a tetrahydrofuran (THF)/water (9/1 v/v) mixed solvent for 24 h at room temperature to produce strands of carbon fibers. On the other hand, there was no change in the appearance of the same BA-CHDMVG-based CFRP board upon acid treatment in water with no organic solvent. To determine their stability against aqueous acid, the BA-CHDMVG-based CFRP boards were immersed in 0.1 mol l−1 aqueous acetic acid solution at room temperature for 30 days and then subjected to tensile testing. The BA-CHDMVG-based CFRPs after the acid treatment exhibited almost the same tensile properties as those of the BA-CHDMVG-based CFRPs before the acid treatment. These results indicate that the BA-CHDMVG-based CFRPs are stable toward acid in the normal living environment, such as acid rain. Recyclable carbon fiber-reinforced plastics (CFRPs) with controlled degradability and stability were developed by using acid-degradable acetal linkage-containing epoxy resin (BA-CHDMVG). The obtained BA-CHDMVG-based CFRPs exhibited almost the same tensile and thermal properties as those of the conventional BA-based CFRPs and underwent smooth degradation through hydrolysis with the treatment of hydrochloric acid in a tetrahydrofuran (THF)/water (9/1) mixed solvent. On the other hand, in the absence of organic solvents, the BA-CHDMVG-based CFRPs have sufficient stability toward acid in the normal living environment.

Substitution of thiourea to poly(diphenylacetylene) having 2-bromoethoxy groups (2a) gave an sulfonium-containing poly(diphenylacetylene) [3a (Br − )]. The counteranions of 3a (Br − ) could be exchanged using CF3COOK and (CF3SO2)2NLi, and the polymers 3a (TFAc − ) and 3a (Tf 2 N − ) were obtained. Polymer 3a (Br − ) was hydrolyzed with NaOHaq to afford the polymer 4a possessing mercapto groups. The CO2 permeability coefficients (\(P_{{{\text{CO}}_{ 2} }}\)) and the separation factor (\(P_{{{\text{CO}}_{ 2} }} /P_{{{\text{N}}_{ 2} }}\)) of 3a (Br − ) were 15 barrers and 16, respectively. The selectivity was low compared to the analogous polymer, poly(diphenylacetylene) having imidazolium salts (\(P_{{{\text{CO}}_{ 2} }} /P_{{{\text{N}}_{ 2} }} = 4 4\)), because 3a (Br − ) interacted strongly with CO2, and the diffusion of CO2 was suppressed. The \(P_{{{\text{CO}}_{ 2} }}\) and \(P_{{{\text{CO}}_{ 2} }} /P_{{{\text{N}}_{ 2} }}\) of 3a (TFAc − ) were 43 barrers and 24, respectively, and those of 3a (Tf 2 N − ) were 52 barrers and 26, respectively. Both permeability and selectivity increased as the counteranion became bulkier. The mercapto group containing poly(diphenylacetylene) (4a) showed a relatively high CO2 permeability (\(P_{{{\text{CO}}_{ 2} }} = 1 30\) barrers).

Polydiphenylacetylene (PDPA) derivaitves consisting of different central atoms of C, Si, and Ge in the pendent group were comparatively investigated in normal, swollen, and acid-treated states. The...

Living cationic copolymerization of vinyl ethers having oxyethylene side chains (MOEO3VE and MOEO4VE) with vinyl ethers having thermal-crosslinkable groups (VEEM and VEEA) provided the random-like copolymers [poly (MOEO3VE-VEEM), poly (MOEO4VE-VEEM), poly (MOEO3VE-VEEA), and poly (MOEO4VE-VEEA)]. The obtained copolymer compositions were almost the same as those of the feed ratios, and the copolymers with various composition ratios were synthesized ([MOEO3VE or MOEO4VE]/[VEEM or VEEA] = 2:1, 4:1, 6:1, 10:1, and 14:1). All the copolymers are sticky liquid before crosslinking, but the relatively tough porous Teflon film-based composite membranes were obtained by thermal crosslinking via mathacrylate groups or acrylate groups. All the membranes showed high CO2 permselectivity (PCO2/PN2 = 40–51) due to the high CO2 solubility selectivity (SCO2/SN2 = 44–61). The CO2 permeability increased as the composition ratios of VEEM and VEEA decreased because the gas diffusivity enhanced by the decrement of crosslinking points. Given the same composition ratio, the increased oxyethylene side chain length is beneficial in enhancing CO2 permeability. The effects of crosslinkable groups on gas permeability were not observed. Poly (MOEO4VE-VEEM) and poly (MOEO4VE-VEEA) showed the excellent performance for CO2 separation (PCO2 = 440 and 460 barrer, PCO2/PN2 = 51).

Diphenylacetylenes having various silyl groups [PhCCC6H4-R; R = p-SiMe3 (TMSDPA), p-SiEt3 (TESDPA), p-SiMe2-n-C8H17 (DMOSDPA), and p-SiPh3 (TPSDPA)] were copolymerized with diphenylacetylene having a tert-butyl group (PhCCC6H4-tertBu; TBDPA) using a TaCl5–n-Bu4Sn catalyst in various monomer feed ratios to provide high-molecular-weight copolymers in high yields. The free-standing membranes were fabricated by solution-casting, except poly(TPSDPA-co-TBDPA). Interestingly, the gas permeability of poly(TMSDPA-co-TBDPA) was higher than those of the homopolymers, poly(TMSDPA) and poly(TBDPA). The permeability of the copolymers became lower as the silyl groups became bulkier. The desilylation of membranes was carried out using a mixture of trifluoroacetic acid/hexane. When bulkier silyl groups were removed, the oxygen permeability increased to larger extents. The oxygen permeability coefficients of the copolymers and desilylated copolymers increased with increasing composition ratio of TBDPA. The gas diffusivity and gas solubility were also increased upon desilylation.

Extremely high gas-permeable polymers were synthesized via the metathesis copolymerization of 1-(3,4-difluorophenyl)-2-(4-trimethylsilylphenyl)acetylene (FS) and 1-(3,4-dichlorophenyl)-2-(4-trimethylsilylphenyl)acetylene (CS). The PO2 values of the copolymers (PFCS) were determined to be 5,600–14,000 barrer. It was found that desilylation remarkably enhanced the gas permeability, with the obtained desilylated membranes (DPFC) exhibiting ultrahigh oxygen permeabilities of 8,300–25,100 barrer, which are the highest among existing polymer materials. The effects of physical aging on the PO2 values of PFCS and DPFC were fairly small, thereby indicating their good stabilities.

Gas separation using separation membranes is highly advantageous as they consume less energy and are environmentally friendly and inexpensive. Substituted poly(diarylacetylene)s are potential materials for gas-separation membrane owing to the excellent permeation performance. Herein, 1-β-naphthyl-2-(4-trimethylsilyl)phenylacetylene (NS) was copolymerized with 1-phenyl-2-(4-tert-butyl)phenylacetylene (TB) and 1-(4-trimethylsilyl)phenyl-2-(4-trimethylsilyl)phenylacetylene (BS) with the TaCl5/n-Bu4Sn catalyst, which afforded high-molecular weight copolymers [poly(NS-TB) and poly(NS-BS)]. The poly(NS-TB) and poly(NS-BS) membranes showed high oxygen permeability (PO2: 3600–6500 barrers). Desilylation of poly(NS-TB) and poly(NS-BS) was carried out using a CF3COOH/hexane mixture to obtain the corresponding desilylated membranes [Dpoly(NS-TB) and Dpoly(NS-BS)]. Desilylation significantly enhanced the gas permeability. The PO2 values of Dpoly(NS-TB) were extremely large (10800–12100 barrers), owing to the large fractional free volume (ca. 0.40). All the membranes maintained a fairly high gas permeability after 150 days of aging. The study results may help in designing better gas separation membranes.

The ABA-type triblock copolymers consisting of poly(2-adamantyl vinyl ether) [poly(2-AdVE)] as outer hard segments and poly(vinyl ether) having polar oxyethylene side chains [poly(MOEO1VE), poly(MOEO2VE), poly(MOEO3VE), or poly(MOEO4VE)] as inner soft segments were synthesized by sequential living cationic polymerization. The triblock copolymer compositions were similar to those of the feed ratios, and [2-AdVE]/[MOEOnVE]/[2-AdVE] ratios of copolymers were all approximately 150/700/150. The obtained triblock copolymers formed microphase-separated structure, and the free-standing membranes were obtained by solution-casting. The CO2 permeability coefficient (PCO2) of triblock copolymer, poly(2-AdVE)-b-poly(MOEO1VE)-b-poly(2-AdVE), was 113 barrer, which is much larger than that of poly(AdVE) [PCO2 = 25.2 barrer]. The permeability increased with increasing the content of the oxyethylene units in the triblock copolymers because the flexibility of the oxyethylene chains enhances gas diffusion in the polymer matrix. The triblock copolymers exhibited high CO2 permselectivity due to the good affinity of oxyethylene units to CO2, and their PCO2/PN2 were as large as 43.2–57.4.

A conformation-variable conjugated polyelectrolyte responding to oppositely charged biomolecules was examined as an imaging agent for the detection of latent fingerprints (LFPs). Sulfonated poly(diphenylacetylene) (SPDPA) produces high-resolution fluorescence (FL) LFP images by simple wetting of the target objects with the polymer solution without any additional treatment. SPDPA readily interacts with LFP sweat components (especially amino acids) via electrostatic interactions, leading to significantly enhanced FL images in a "turn-on" mode. The FL emission enhancement was examined in a model reaction between SPDPA and an amino acid standard. Visualization with SPDPA is effective on various surfaces, including both rough (paper) and smooth (glass and plastic) ones. Moreover, SPDPA readily interacts with extremely thin sweat LFPs, especially on smooth glass surfaces.

Diphenylacetylenes possessing both an n -octyloxy group and a substituent groups (H: 1a , phenyl: 1b , naphthyl: 1c , anthryl: 1d , biphenyl: 1e ) were polymerized using TaCl 5 / n -Bu 4 Sn. Diarylacetylenes having bulky aromatic groups such as α-naphthyl and 9-anthryl cannot afford high-molecular-weight polymer, but the present monomers polymerized to afford relatively high-molecular-weight polymers ( M n = 222,000–596,000) because they have a phenyl spacer between bulky aromatic group and reactive part of C≡C. The solubility of 2a - c and 2e exhibited good solubility in relatively low polar solvents because of long alkyl groups. The emission maxima of 2b - e were all 512 nm, which was longer than that of 2a . No difference of emission maximum among 2b - e were observed in solution. However, the emission maxima in film of 2b , 2c , 2d , and 2e were 530, 526, 524, and 542 nm, respectively. Compared to the emission in solution, that of 2b and 2e in film exhibited large shifts while that of 2c and 2d exhibited smaller shifts. This is because the bulky aromatic groups of naphthyl and anthryl hardly took coplanar structures owing to the steric hindrance.

Sulfonated poly(diphenylacetylene) (SPDPA) is used as an anionic conjugated polyelectrolyte to examine stoichiometric electrostatic self-assembly with homologous cationic surfactants (octadecyl)X(methyl)Y ammonium bromides (OXMYABs) having different numbers of long hydrophobic tails. The SPDPA–OXMYAB complexes formed show significantly increased water contact angle and enhanced fluorescence (FL) emissions compared with the pristine SPDPA. The complexes exist in a gum state at room temperature owing to the plasticizer effect of the hydrophobic tails, hence they are very soft and highly stretchable. The hydrophobicity, softness, and FL quantum efficiency of the SPDPA–OXMYAB complexes increase as the number of hydrophobic tails increases. SPDPA adsorbs uniformly onto filter papers to produce fluorescent papers. The SPDPA-adsorbed papers have many unique applications, including FL image writing, fingerprinting, stamping, and inkjet printing using the surfactant solutions as an ink to reveal high-resolution FL images. In particular, multideposit inkjet-printing using SPDPA and OXMYAB solutions as inks produces water-resistant, embedded figures in paper currency.

Diphenylacetylenes containing electron-donating groups ( O- n -C 8 H 17 : 1A , OCH 3 : 1B , SCH 3 : 1C ) and electron-withdrawing groups ( COOCH 3 : 1a , COCH 3 : 1b , CF 3 : 1c , CN: 1d ) were polymerized using TaCl 5 / n -Bu 4 Sn. The polymerization of diphenylacetylenes possessing both an n -octyloxy group and an electron-withdrawing group ( 1Aa , 1Ab , 1Ac ) was also examined in the same conditions. Electron-donating group-containing monomers ( 1A – C ) polymerized to afford relatively high-molecular-weight polymers ( M n = 240,000–622,000). Ester-containing monomers ( 1a and 1Aa ) also polymerized to give polymers with high molecular weights, while the polymerization of acetyl- and trifluoromethyl-containing monomers ( 1b , 1c , 1Ab , 1Ac ) gave low-molecular-weight polymers. Cyano-containing monomer ( 1d ) did not polymerize because cyano groups deactivated tantalum catalysts. Polymers having electron-donating groups ( 2A–C ) emitted green-colored lights, and the emission maxima were around 505 nm. Ester-containing polymers 2a and 2Aa showed yellow-colored emissions, and the emission maxima were 520 nm. These polymers showed emission red-shifts between the solution and cast film.

1-(p-Trimethylsilyl)phenyl-2-(p-trimethylsilyl)phenylacetylene (1a) was copolymerized with 1-phenyl-2-(4-tert-butyldimethylsiloxy)phenylacetylene (1b) in various monomer feed ratios with TaCl5-n-Bu4Sn as a catalyst to give high-molecular-weight copolymers (2 ab) in good yields. Membranes of 2 ab exhibited very high gas permeability. Especially, with the monomer feed ratio of 1a:1b = 2:1, the PCO2 and PO2 values reached 8500 and 2700 barrers, respectively. Decomposition of the siloxy groups of 2 ab with n-Bu4N+F− provided diphenylacetylene copolymers containing both silyl and hydroxy groups (3 ab). Membranes of 3 ab showed lower gas permeability and higher gas permselectivity than 2 ab. Moreover, desilylation of 2 ab using trifluoroacetic acid afforded membranes with only hydroxy groups (4 ab), which showed even lower gas permeability and higher gas permselectivity than 3 ab (PCO2/PN2 and PO2/PN2 = 48–74 and 6.8–12, respectively). The data points for 4 ab in the PO2 versus PO2/PN2 plot were located obviously above the 2008 Robeson upper bound.

Diphenylacetylene monomers bearing a methylol group protected by a t-butyldiphenylsilyl group [tBuPh2SiOCH2C6H4C CC6H4R; R = SiMe3 (1a) and R = SiMe2nC18H37 (1b)] were synthesized and then polymerized with TaCl5/n-Bu4Sn to afford the corresponding poly(diphenylacetylene)s 2a and 2b, respectively. The molecular weights of 2a and 2b were high (i.e., Mw = 1,020,000 and 1,560,000, respectively), and free-standing membranes were obtained by solution casting. The deprotection of membranes of 2a and 2b using n-Bu4N+F− afforded poly(diphenylacetylene)s bearing methylol and silyl groups (3a and 3b). On the other hand, treatment of membranes of 2a and 2b with trifluoroacetic acid led to deprotection and desilylation, producing poly(diphenylacetylene)s bearing trifluoroacetate moieties (4a and 4b, respectively), and then treatment with methanol afforded poly(diphenylacetylene)s bearing only methylol groups (5a and 5b). The carbon dioxide permeability coefficients (PCO2) of membranes of 2a and 2b were 99 and 78 Barrer, respectively. Deprotection led to the increment of CO2 permeability without the decline of the CO2 permselectivity. Poly(diphenylacetylene)s bearing methylol and silyl groups (3a and 3b) exhibited high permeability (PCO2 = 2000 and 120 Barrer, respectively), but not high permselectivity (PCO2/PN2 = 17 and 16, respectively). Methylol-group-containing poly(diphenylacetylene) without silyl groups 5b exhibited the best CO2 permeation property, i.e., high CO2 permeability and high permselectivity (PCO2 = 220 Barrer, PCO2/PN2 = 32).

Disubstituted p-dibromobenzenes having alkoxy groups polymerized to give relatively high molecular weight polymers (M n=14 700–49 600) in good yields. Polymers exhibited high thermal stability, and the decomposition temperatures were higher than 350 °C. From the differential scanning calorimetry thermograms, polymers showed melting of crystallites or glass transitions. The free-standing membranes could be prepared by the hot-press method. The membrane possessing hexyl side chains exhibited relatively high gas permeability, and the oxygen permeability coefficient was 25.6 barrer, higher than those previously reported for poly(p-phenylene)s having ester substituents.

The combination of living/controlled cationic cyclopolymerization and crosslinking polymerization of bifunctional vinyl ethers (divinyl ethers) was applied to the synthesis of core-crosslinked star-shaped polymers with rigid cyclized arms. Cyclopolymerization of 4,4-bis(vinyloxymethyl)cyclohexene (1), a divinyl ether with a cyclohexene group, was investigated with the hydrogen chloride/zinc chloride (HCl/ZnCl2) initiating system in toluene at 0 °C. The reaction proceeded quantitatively to give soluble poly(1)s in organic solvents. The content of the unreacted vinyl groups in the produced polymers was less than ∼3 mol%, and therefore, the degree of cyclization of the polymers was determined to be ∼97%. The number-average molecular weight (Mn) of the polymers increased in direct proportion to monomer conversion and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that living cyclopolymerization of 1 occurred. The chain linking reactions among the formed living cyclopolymers with 1,4-bis(vinyloxy)cyclohexane (3) as a crosslinker in toluene at 0 °C produced core-crosslinked star-shaped cyclopoly(1)s [star-poly(1)s] in high yield (100%). Dihydroxylation of the cyclohexene double bonds of star-poly(1) gave hydrophilic water-soluble star-shaped polymers with rigid arm structure [star-poly(1)-OH] with thermo-responsive function in water. Tgs of star-poly(1) and star-poly(1)-OH were 135 °C and 216 °C, respectively; these values are very high as vinyl ether-based star-shaped polymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1094–1102

When aqueous conjugated-polyelectrolyte colloidal solutions containing an adequate amount of surfactant with an appropriate hydrophile-lipophile balance were sprayed onto latent fingerprints (LFPs), the polymer nanoparticles were readily transferred to the LFPs to reveal highly distinguishable fluorescent images, while the LFPs themselves remained intact.

Poly(diphenylacetylene) [PDPA] derivatives were nitrated using a mixture of nitric acid and sulfuric acid. Nitration of poly[1-( p -trimethylsilyl)phenyl-2-phenylacetylene] ( 1a ) proceeded, and the nitro groups were substituted to trimethylsilyl groups on benzene rings. The degree of nitration (DN) increased with reaction time, and it reached 0.41 for 3.0 h. Fluorine-containing PDPA ( 1b and 1c ) showed less reactivity for nitration, and the DNs were only 0.18 and 0.06, respectively, under the same conditions. Nitration of PDPAs having n -butyl and t -butyl groups ( 1d and 1e ) afforded the nitrated PDPAs, whose DN were 0.20 and 0.14, respectively. Reduction of nitro groups on PDPAs proceeded quantitatively to produce the corresponding PDPAs possessing amino groups ( 3a - e ). Aminated PDPAs exhibited high CO 2 permselectivity compared to the corresponding non-aminated PDPAs. The CO 2 permeability coefficients of aminated PDPAs ( 3a - d ) were lower than those of the corresponding polymers ( 1a - d ) because the polymer chain packing was strengthened by the intermolecular interaction between polar amino groups, but t -butyl group-containing aminated PDPA ( 3e ) showed high CO 2 permeability than 1e because the chain packing was weakened by the steric repulsion of bulky t -butyl groups.

Diphenylacetylenes having a diisopropylphenoxysilyl, 2-bromoethoxy, trimethylsilyl and t-butyl groups (p-PhOSi(i-Pr)2C6H4C≡CC6H4-p-SiMe3 (1a), p-(BrCH2CH2O)C6H4C≡CC6H4-p-SiMe3 (1b), PhC≡CC6H4-p-SiMe3 (1c), PhC≡CC6H4-p-t-Bu (1d)) were polymerized to provide the corresponding poly(diphenylacetylene)s (2a–d). Treatment of the membrane of 2a with n-Bu4N+F− gave silanol-functionalized poly(diphenylacetylene) (3a). Fourier transform-infrared spectroscopy spectrum of 3a revealed that some silanol groups were consumed and the polymer was crosslinked via siloxane bond. The membrane of 3a exhibited very high gas permeability irrespective of the presence of polar silanol groups. Substitution of 1-methylimidazole to the membrane of 2b afforded an imidazolium salt-containing poly(diphenylacetylene) (3b (Br−)). Counteranions of 3b (Br−) could be exchanged by the treatment of the membrane with CF3COOK and (CF3SO2)2NLi, and membranes of 3b (TFAc−) and 3b (Tf2N−) were obtained. Introduction of 1-methylimidazole remarkably increased the selectivity (PCO2/PN2=31–44). The PCO2 values of 3b (Br−), 3b (TFAc−) and 3b (Tf2N−) were 11, 23 and 53 barrers, respectively, indicating that the CO2 permeability increased as the counteranion became bulkier. Polymers 2c and 2d were sulfonated using acetyl sulfate to give sulfonated poly(diphenylacetylene)s (3c and 3d). Polymer 3c exhibited high CO2 permselectivity, and the PCO2/PN2 was as large as 54. Polymer 3d with t-butyl groups showed relatively large PCO2 of 180 barrers and PCO2/PN2 of 30. Partially crosslinked poly(diphenylacetylene) (3a) bearing silanol groups were synthesized by the treatment of the membrane of 2a with n-Bu4N+F−. Imidazolium salt-containing poly(diphenylacetylene) (3b (Br−)) was obtained by the substitution of 1-methylimidazole to the membrane of 2b. Sulfonation of 2c gave a sulfonated poly(diphenylacetylene) (3c). The membrane of 3a was found to exhibit high gas permeability irrespective of the presence of the polar silanol groups in the polymer. Introduction of 1-methylimidazole into the membrane remarkably increased the CO2/N2 selectivity (PCO2/PN2=31–44). The sulfonated polymer 3c exhibited high CO2 permselectivity, and the PCO2/PN2 was as large as 54.

Cationic polymerization of 2-adamantyl vinyl ether (2-vinyloxytricyclo[3.3.1.13,7]decane; 2-AdVE) and copolymerization of 2-AdVE with n-butyl vinyl ether (NBVE), 2-methoxyethyl vinyl ether (MOVE), or 2-(2-vinyloxyethoxy)ethyl acrylate (VEEA), vinyl ethers containing a flexible chain or a polymerizable group, were performed to obtain poly(vinyl ether) plastics for optical use. With the living cationic initiating systems such as isobutyl vinyl ether–acetic acid adduct/ethylaluminum sesquichloride (IBEA/Et1.5AlCl1.5) or the hydrogen chloride/zinc chloride (HCl/ZnCl2), all the obtained copolymers had unimodal and relatively narrow molecular weight distributions (polydispersity ratio: M w/M n = ~1.5 at high conversion) throughout the copolymerizations. These results indicate that the copolymerizations of 2-AdVE with the three comonomers led to the statistical copolymers without contamination of homopolymers. With BF3OEt2 as an initiator, homopolymer of 2-AdVE and poly(2-AdVE)-based polymers, poly(2-AdVE-stat-NBVE), poly(2-AdVE-stat-MOVE), and poly(2-AdVE-stat-VEEA), were produced with high-molecular weights (M n = 31,800–116,000) in toluene at −30 °C in quantitative yield within 10 min. They have excellent thermal stability owing to their high glass transition and thermal decomposition temperatures. The transparency (86–91 %) and refractive index (1.52–1.53) of the molded polymers are similar to those of conventional optical plastics such as poly(methyl methacrylate) (PMMA) and polycarbonate (PC), whereas their specific gravity (1.09–1.12) and water absorption (0.06–0.17 %) are significantly lower than those of PMMA and PC. In addition, the Abbe number of poly(2-AdVE), poly(2-AdVE-stat-NBVE), and poly(2-AdVE-stat-MOVE) exceeded 60 and was higher than those of PMMA and PC, indicating that the poly(2-AdVE)-based plastics are very suitable for optical lens.

Diphenylacetylene having a trimethylsilyl group and two methoxy groups [ p -(CH 3 ) 3 SiC 6 H 4 C CC 6 H 4 - m,p -(OCH 3 ) 2 ( 1a )] polymerized with TaCl 5 / n -Bu 4 Sn catalyst to provide a high-molecular-weight polymer ( 2a ). In contrast, monomers without trimethylsilyl group ( 1b ) and having two t -butyldimethylsiloxy groups ( 1c ) hardly polymerized because of poor solubility of the produced polymer 2b and steric hindrance of 1c . Polymer 3a with high molecular weight was obtained by desilylation of 2a using CF 3 COOH. Membranes having p,m -dihydroxyphenyl groups to certain degrees ( 4a : 40%; 4b 90%) were synthesized by cleavage of methoxy groups in the membrane of 3a using AlCl 3 . Membrane 4a showed high CO 2 permselectivity, while membrane 5a was too brittle. Polymers 2a and 3a totally dissolved in CHCl 3 and THF, and their solutions turned into gels upon addition of metal chlorides such as TaCl 5 , AlCl 3 , etc. The gels returned to solutions by adding a small amount of methanol. This indicates that 2a and 3a form non-covalent intermolecular bonds through metal–ligand interaction.

Cationic copolymerizations of vinyl ether monomers having a triethylene glycol segment [2-(2-(2-methoxyethoxy)ethoxy)ethyl vinyl ether (TEGMVE)] with vinyl ether monomer having a methacrylate unit [2-(2-vinyloxyethoxy)ethyl methacrylate: VEEM] were performed to obtain crosslinkable copolymers [poly(TEGMVE-VEEM)] with different composition rates. Methacrylate groups in poly(TEGMVE-VEEM)s partially reacted to give crosslinked polymer membranes. The free-standing membranes of poly(TEGMVE-VEEM)s obtained at monomer feed ratios of 6:1, 10:1, and 14:1 were too brittle, while their composite membranes with PTFE sheet were tough enough to measure gas permeability. All the membranes of poly(TEGMVE-VEEM) showed high CO 2 /N 2 selectivity ( P CO 2 / P N 2 = 35–54) because of their high CO 2 solubility selectivity ( S CO 2 / S N 2 = 38–61). The gas permeability increased as the composition ratio of VEEM decreased, and the composite membrane of poly(TEGMVE-VEEM)(14:1) showed the highest CO 2 permeability ( P CO 2 = 410 barrers) among the present polymer membranes.