Synthesis of block copolymers containing 1-chloro-2-phenylacetylene, 2-nonyne, and (p-n-butyl-o,o,m,m-tetrafluorophenyl)acetylene through sequential living polymerization by MoOCl4-based catalysts

Block copolymerization of 1-chloro-2-phenylacetylene (ClPA), 2-nonyne, and (p-n-butyl-o,o,m,m-tetrafluorophenyl)acetylene (p-BuF4PA) as novel comonomers through the sequential addition process was studied by use of MoOCl4-based living polymerization catalysts. The acetylenes that are known to undergo living polymerization and block copolymerization, i.e. 1-chloro-1-octyne (ClOc), [o-(trimethylsilyl)phenyl]acetylene (o-Me3SiPA), and [o-(trifluoromethyl)phenyl]acetylene (o-CF3PA) were employed as conventional comonomers. When ClPA was used in combinations with these conventional comonomers, diblock copolymers with narrow molecular weight distribution were selectively formed in the presence of MoOCl4-n-Bu4Sn-EtOH irrespective of the order of monomer addition. On the other hand, 2-nonyne and p-BuF4PA selectively produced block copolymers with the conventional comonomers only when the comonomers were supplied in suitable addition orders. Several diblock copolymers with higher molecular weight were obtained by using either MoOCl4-Et3Al-EtOH or MoOCl4-n-BuLi catalyst, which is due to their lower initiation efficiencies. Use of MoOCl4-n-Bu4Sn-EtOH enabled the preparation of ABA-type triblock copolymers composed of ClPA and ClOc. ABC-type triblock copolymers were produced using MoOCl4-n-Bu4Sn-EtOH from o-Me3SiPA, o-CF3PA, and p-BuF4PA.