Poly(phenylacetylene)s Carrying Siloxy, Carbonate, and Hydroxy Groups: Synthesis and Properties

Abstract t ‐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)RhBPh 4 ] ( 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(SiMe 3 ) 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