Hiroaki Kouzai

Polymerization and polymer properties of diarylacetylenes

Abstract The polymerization of three diarylacetylenes, namely 1-( p -benzylphenyl)-2-phenylacetylene ( p -BzDPA), 1-( p -phenylphenyl)-2-phenylacetylene and 1-(β-naphthyl)-2-phenylacetylene, was examined. These monomers polymerized in good yields with TaCl 5 -cocatalyst systems. Poly( p -BzDPA) was soluble in various organic solvents and had high molecular weights of 6 × 10 5 −9 × 10 5 according to gel permeation chromatography. In contrast, the other two polymers were insoluble in all solvents. All these polymers had fairly good thermal stability in air (their onset temperatures of weight loss in air were 330–450°C). The oxygen permeability coefficient of poly( p -BzDPA) at 25°C was 18 barrers, which was close to that of natural rubber (23 barrers).

Synthesis and properties of poly(diphenylacetylenes) having ether linkages

SummaryPolymerization of 1-phenyl-2-(p-phenoxyphenyl)acetylene (p-PhODPA), 1-phenyl-2-(p-methoxyphenyl)acetylene, and 1-phenyl-2-(p-n-butoxyphenyl)acetylene was examined. These monomers polymerized with TaCl5-n-Bu4Sn to give methanol-insoluble polymers in over 60% yields. Poly(p-PhODPA) was a yellow solid completely soluble in toluene, CHCl3, etc., and its weight-average molecular weight was about 1.0x106 or higher. This polymer was thermally very stable (the onset temperature of weight loss in TGA in air was 420 °C). Its oxygen permeability coefficient (Po2) was 37 barrers (Po2/Pn2 2.2) and similar to that of natural rubber. In contrast, the other two polymers did not completely dissolve in any organic solvent, and their thermal stability was lower.

Polymerization and polymer properties of (2-methyl-5-tert-butylphenyl)acetylene: steric effects of the ring substituents

Summary(2-Methyl-5-tert-butylphenyl)acetylene (2Me5tBuPA) polymerized in the presence of MoCl5-n-Bu4Sn catalyst in 1,4-dioxane to give a high molecular weight polymer

Synthesis and properties of poly (diphenylacetylenes) having aliphatic para‐substituents

(\overline M _w {\text{ }}8x10^5 )

Chain transfer reaction to terminal olefins in the polymerization of 1‐phenyl‐1‐propyne with Nb and Ta catalysts

. Not only MoCl5- but also WCl6-based catalysts were effective. The polymer obtained was a dark brown solid, soluble in organic solvents such as toluene and CHCl3, and formed a freestanding film by solution casting. The onset temperature of weight loss of the polymer in air was 260 °C. Its oxygen permeability coefficient was 43 barrers, which is twice that of natural rubber. Differences from the results (usually lower molecular weight, not film-forming, and thermally less stable) of both poly(phenylacetylene) and poly[o-methylphenyl)acetylene] are attributable to the synergistic steric effect of the o-methyl and m-tert-butyl groups.

Chain transfer reaction in the polymerization of substituted acetylenes. II. Chain transfer reaction to trimethylvinylsilane in the polymerization of disubstituted acetylenes by MoCl5–n‐Bu4Sn

Trimethylvinylsilane works as an effective chain transfer agent in the polymerisation of various substituted acetylenes by Mo and W catalysts, which enables the control of polymer molecular weight and verifies the metal-carbene mediated polymerisation mechanism.