Polymerization of several diphenylacetylene derivatives was carried out by using TaCl5-n-Bu4Sn as catalyst. C6H5C≡CC6H4-p-OSi(CH3)2t-Bu (3a) and C6H5C≡CC6H4-m-OSi(CH3)2t-Bu (3b) provided the corresponding polymers (poly(3a), poly(3b)) with high molecular weights in good yields,Desilylation of poly(3a) and poly(3b) membranes catalyzed by trifluoroacetic acid yielded poly(diphenylacetylenes) having free hydroxyl groups [poly(4a), poly(4b)], which are the first examples of highly polar group-carrying poly(diphenylacetylenes). Poly(3a) and poly(3b) dissolved in nonpolar solvents such as toluene and chloroform, while poly(4a) and poly(4b) were insoluble in these solvents. According to TGA in air, poly-(3a) and poly(3b) were thermally fairly stable among substituted polyacetylenes, and poly(4a) and poly-(4b) displayed even higher thermal stability. The P CO2/PCH4 and PCO 2 /PN 2 permselectivity ratios of poly(4a) and poly(4b) membranes were as large as 13-46, while keeping relatively high PCO 2 values.

Diphenylacetylenes possessing fluorine atom(s) and a siloxy group (1c-i) were polymerized with TaCl 5 -n-Bu 4 Sn. Monomers 1c-f having a siloxy group at the para position of a phenyl ring produced high molecular weight polymers (2c-f) in good yields. These polymers afforded tough free-standing membranes by casting their toluene solution. Desilylation of the polymer membranes was carried out with trifluoroacetic acid to give membranes of poly(diphenylacetylenes) having fluorine atoms and hydroxyl groups (3c-f). Polymers 2c-f were soluble in various organic solvents such as toluene, CHCl 3 , and THF, while polymers 3c-f were insoluble in these solvents. All the polymers 2c-f and 3c-f exhibited high thermal stability. The gas permeability of most membranes in the present study (2d-f and 3c-f) were higher than those of the corresponding polymers without fluorine atoms (2a and 3a), indicating that incorporation of fluorine atoms into the polymers enhances gas permeability. The P CO2 /P N2 permselectivity ratios of polymers 3c-f were as large as 36-48, and the points of 3c-f in the P CO2 vs P CO2 /P N2 plot were located above Robeson's upper bound.

No abstract

Poly(diphenylacetylene)s having various silyl groups are soluble in common solvents, from whose membranes poly(diphenylacetylene) membranes can be obtained by desilylation. The oxygen permeability coefficients of the desilylated polymers are quite different from one another (120-3300 barrers) irrespective of the same polymer structure. When bulkier silyl groups are removed, the oxygen permeability increases to larger extents. Poly[1-aryl-2-p-(trimethylsilyl)phenylacetylene]s are soluble in common solvents, and afford free-standing membranes. These Si-containing polymer membranes are desilylated to give the membranes of poly[1-aryl-2-phenylacetylene]s. Both of the starting and desilylated polymers show very high thermal stability and high gas permeability. 1-Phenyl-2-p-(t-butyldimethylsiloxy)phenylacetylene polymerizes into a high-molecular-weight polymer. This polymer is soluble in common organic solvents to provide a free-standing membrane. Desilylation of this membrane yields a poly(diphenylacetylene) having free hydroxyl groups, which is the first example of a highly polar group-carrying poly(diphenylacetylene). The P CO 2 /P CH 4 and P CO 2 / P N 2 permselectivity ratios of poly(1-phenyl-2-p-hydroxylphenylacetylene) membrane are as large as 47.8 and 45.8, respectively, while keeping relatively high P CO 2 of 110 barrers. V V C

Abstractt‐Butyldimethylsilyl (t‐BDMS) and t‐butoxycarbonyl (t‐Boc) protected 3‐ and 4‐hydroxyphenylacetylene monomers were synthesized and polymerized using [(nbd)RhCl]2 (1) and [(nbd)RhBPh4] (2) catalysts. The t‐BDMS‐containing polymers [poly(3a) and poly(4a)] were obtained in good yield (45–69%) while the t‐Boc‐protected monomers polymerized in a high yield [poly(5a) and poly(6a): 80–100%]. The use of KN(SiMe3)2 as a cocatalyst in conjunction with 1 led to a dramatic increase in the molecular weight of the polymers. The acid‐catalyzed removal of the t‐BDMS group afforded the naked hydroxy‐containing polymers [poly(3b) and poly(4b)] which cannot be obtained directly by the polymerization of the corresponding monomers. The polymers containing protected OH moieties were more soluble in less polar solvents, whereas their deprotected counterparts displayed good solubility in polar protic or highly polar aprotic solvents. The attempts to accomplish the free‐standing membrane fabrication by solution casting were successful only for poly(3a) and an augmentation in the gas permeability was discerned in comparison with the unsubstituted poly(phenylacetylene) and poly(o‐methylphenylacetylene).magnified image