Synthesis of Asymmetric Star-Branched Polymers Having Two Polyacetylene Arms by Means of Living Anionic Polymerization Using 1,1-Diphenylethylene Derivatives

Two series of new 3-arm AE 2, 4-arm ABE 2, 5-arm ABCE 2, and 5-arm AD 2 E 2, 6-arm ABD 2 E 2, 7-arm ABCD 2 E 2 asymmetric star-branched polymers have been synthesized using living anionic polymers and 3,5-bis(3-(4-(1-phenylethenyl)phenyl)propoxy)benzyl bromide. The A, B, C, D, and E arms were polystyrene (A), poly(α-methylstyrene) (B), poly(4-methoxystyrene) (C), poly(4-trimethylsilylstyrene) (D), and poly(4-methylphenylvinyl sulfoxide) (E) segments. The methodology involves an addition reaction of either sec -BuLi or poly(4-trimethylsilylstyryl)lithium with two 1,1-diphenylethylene (DPE)-chain-functionalized polymers and a subsequent living anionic polymerization of 4-methylphenylvinyl sulfoxide in situ initiated with the two 1,1-diphenylalkyl anions generated by the addition reaction. Three DPE-functionalized polymers herein used were chain-end-functionalized polystyrene, in-chain-functionalized AB diblock copolymer, and core-functionalized 3-arm ABC star-branched polymer with two DPE moieties at chain end, junction between blocks, and core position, respectively. The molecular characterization results revealed a high degree of structural and compositional homogeneity in each of all the resulting asymmetric star-branched polymers. By thermal treatment of these stars at 150 °C, the two poly(4-methylphenylvinyl sulfoxide) arms introduced into each star were completely converted to polyacetylene segments as confirmed by FT-IR, elemental analysis, and TGA measurements. Thus, novel six asymmetric star-branched polymers having two polyacetylene arms could be successfully synthesized.