Toshio Masuda

Synthesis and properties of polyacetylenes with adamantyl groups

Three disubstituted acetylenes with an adamantyl group—1-(p-adamantylphenyl)-2-chloroacetylene (ClpAdPA), 1-(p-adamantylphenyl)-1-propyne (pAdPP), and 1-(p-adamantylphenyl)-2-phenylacetylene (pAdDPA)—polymerized in good yields in the presence of MoCl5- or TaCl5-based catalysts. The highest weight-average molecular weights of poly(ClpAdPA), poly(pAdPP), and poly(pAdDPA) reached 3.6 × 105, 1.1 × 106, and 6.0 × 106, respectively. The polymers were yellow to white solids and completely soluble in toluene, chloroform, and so forth. These polymers thermally were fairly stable, and the onset temperatures of weight loss in air were over 360 °C. Poly(pAdPP) and poly(pAdDPA) provided free-standing films by solution casting, and their oxygen permeability coefficients (PO2) at 25 °C were 8.6 and 55 barrers [1 barrer = 1 × 10−10 cm3 · (STP) · cm/(cm2 · s · cm Hg)], respectively, which are relatively small compared to those of other substituted polyacetylenes.

Gas permeability and hydrocarbon solubility of poly[1‐phenyl‐2‐[p‐(triisopropylsilyl)phenyl]acetylene]

The effects of film thickness, physical aging, and methanol conditioning on the solubility and transport properties of glassy poly[1-phenyl-2-[p-(triisopropylsilyl) phenyl]acetylene] are reported at 35 °C. In general, the gas permeability coefficients are very high, and this polymer is more permeable to larger hydrocarbons (e.g., C3H8 and C4H10) than to light gases such as H2. The gas permeability and solubility coefficients are higher in as-cast, unaged films than in as-cast films aged at ambient conditions and increase to a maximum in both unaged and aged as-cast films after methanol conditioning. For example, the oxygen permeability of a 20-μm-thick as-cast film is initially 100 barrer and decreases to 40 barrer after aging for 1 week at ambient conditions. After methanol treatment, the oxygen permeabilities of unaged and aged films increase to 430 and 460 barrer, respectively. Thicker as-cast films have higher gas permeabilities than thinner as-cast films. Propane and n-butane sorption isotherms suggest significant changes in the nonequilibrium excess free volume in these glassy polymer films due to processing history. For example, the nonequilibrium excess free volume estimated from the sorption data is similar for as-cast, unaged samples and methanol-conditioned samples; it is 100% higher in methanol-conditioned films than in aged, as-cast films. The sensitivity of permeability to processing history may be due in large measure to the influence of processing history on nonequilibrium excess free volume and free volume distribution. The propane and n-butane diffusion coefficients are also sensitive to film processing history, presumably because of the dependence of diffusivity on free volume and free volume distribution.

Polymerization of diphenylacetylenes having very bulky silyl groups and polymer properties

Polymerization and polymer properties of 1-phenyl-2-[4-(triphenylsilyl)-phenyl]acetylene (pPh 3 SiDPA) and 1-phenyl-2-[4-(triisopropylsilyl)phenyl]acetylene (piPr 3 SiDPA), which have very bulky silyl groups, were examined. These monomers polymerized in good yields in the presence of TaCl 5 -based catalysts. The highest weight-average molecular weights of poly(pPh 3 SiDPA) and poly(piPr 3 SiDPA) reached about 1 × 10 6 and 4.8 × 10 6 , respectively. The polymers were yellow to orange-colored solids which were soluble in toluene, chloroform, etc., and provided free-standing films by solution casting. The onset temperatures of weight loss of poly(pPh 3 SiDPA) and poly(piPr 3 SiDPA) in TGA in air were 430 and 270°C, respectively. The oxygen permeability coefficients of poly(pPh 3 SiDPA) and poly(piPr 3 SiDPA) at 25°C were 3.8 and 20 barrers, respectively, and relatively small.

Influence of deformation and chemical structure on elementary free volumes in glassy polymers

Abstract In the scope of the mechanism of positronium formation in polymers before trapping by elementary free volumes (EFV), we demonstrate an approach to quantitative analyses of experimental results. Correspondingly, a relation between the EFV concentration and annihilation characteristics (lifetimes and intensities) is derived. We use PATFIT and CONTIN analyses of positron annihilation lifetime spectra and obtain information on some heterogeneity of the structure of glassy polymers and on the mechanism of the plastic flow of glassy material.

Synthesis, characterization, and oxygen permeability of homo- and copolymers from p-[tris(trimethylsilyl)silyl]-phenylacetylene

SummaryHomopolymerization of p-[tris(trimethylsilyl)silyl]phenylacetylene [p(Me3Si)3SiPA] by Rh catalyst provided insoluble polymer. On the other hand, copolymerization of p(Me3Si)3SiPA with p-(trimethylsilyl)phenylacetylene (pMe3SiPA) at 80:20, 50:50, and 20:80 feed ratios afforded high molecular weight copolymers (Mw > 1×106), all of which were soluble in common solvents such as toluene and chloroform. The mole ratios of p(Me3Si)3SiPA to pMe3SiPA unit in copolymers were close to those in the feeds. The oxygen permeability increased monotonously with increasing p(Me3Si)3SiPA content of copolymer in correspondence with fractional free volume; the value of the copolymer for the 80:20 feed ratio reached 770 barrers.

SYNTHESIS AND PROPERTIES OF COPOLYMERS FROM 1-[3,5-BIS(TRIMETHYLSILYL)PHENYL]-2-PHENYLACETYLENE

Copolymerization of 1-[3,5-bis(trimethylsilyl)phenyl]-2-phenylacetylene (m,m-(Me3Si)2DPA) with other diphenylacetylene derivatives and their copolymer properties were investigated. Homopolymerization of m,m-(Me3Si)2DPA by TaCl5─n-Bu4Sn (1:2) did not give the polymer due to steric hindrance. However, m,m-(Me3Si)2DPA copolymerized with diphenylacetylene (DPA), 1-phenyl-2-[p-(trimethylsilyl)phenyl]acetylene (p-Me3Si DPA), and 1-phenyl-2-[m-(trimethylsilyl)phenyl]acety-lene (m-Me3SiDPA) in the presence of TaCl5─n-Bu4Sn at various feed ratios to give copolymers in moderate yields. The formed copolymers were yellow to orange solids, which were soluble in common organic solvents such as toluene and CHCl3. The highest weight-average molecular weights (Mw) of these copolymers reached ca. 6 × 105 and tough films could be obtained by solution casting. Their onset temperatures of weight loss in air were observed around 400°C, indicating high thermal stability. The oxygen permeability coefficients at 25°C of copoly(m,m-(Me3Si)2 DPA/DPA) (feed ratio 1:1) and copoly(m,m-(Me3Si)2DPA/p-Me3SiDPA) (feed ratio 1:2) were 21 and 100 barrers, respectively, medium in magnitude among polymers from substituted acetylenes.