Well‐defined Syndiotactic Polystyrene‐b‐Atactic Polystyrene Stereoblock Polymers

Abstract

New well-defined syndiotactic polystyrene-atactic polystyrene (sPS-b-aPS) stereoblock polymers were synthesized in a two-step process using a combination of "pseudo-living" Ziegler-Natta and atom transfer radical polymerizations. Under specific conditions, the one-pot termination with N-bromosuccinimide of syndioselective styrene polymerization catalyzed by Cp*Ti(CH(2) Ph)(3) /B(C(6) F(5) )(3) /Al(n-Oct)(3) (1:1:1) provided sPS-Br polymers almost perfectly (97%) end-capped with bromine atoms. These sPS-Br were used as macroinitiators in the ATRP of styrene affording sPS-b-aPS with a broad range of compositions. Characterizations by (1) H and (13) C NMR spectroscopy, HT-GPC and DSC confirmed the formation and identity of the new materials. Preliminary studies on the crystallization behavior under both isothermal and non-isothermal conditions showed that these sPS-b-aPS stereoblock polymers crystallize faster than the corresponding blends made of sPS and aPS with a similar composition; this effect is amplified at high contents (80%) of aPS in the stereoblock materials.

Synthesis and characterization of soft-hard stereoblock polybutadiene with Fe(2-EHA)3 /Al(i -Bu)3 /DEP catalyst system

“…The signals located at 4.8-5.1 ppm were assigned to the vinyl methylene protons of the 1,2-unit and whose intensity increased with the increment of monomer feed ratio in the polymerization. Furthermore, the sequence structure and stereoisomerism of polymer were analyzed by 13 C NMR spectra (Figure 3). [30][31][32][33] The peaks around 115 and 144 ppm were assigned to the vinyl methylene and methane carbons of 1,2 unit, respectively.…”

“…Matyjaszewski and coworkers synthesized isotactic‐ b ‐atactic poly( N , N ‐dimethylacrylamide) through atom‐transfer radical polymerization (ATRP) by the addition of Lewis acids in polymerization process . Carpentier and coworkers reported the synthesis of well‐defined syndiotactic polystyrene‐ b ‐atactic polystyrene stereoblock polymers in a two‐step process by the combination of “pseudo‐living” Ziegler‐Natta polymerization and ATRP …”

“…[10][11][12] Carpentier and coworkers reported the synthesis of well-defined syndiotactic polystyrene-b-atactic polystyrene ster-eoblock polymers in a two-step process by the combination of "pseudo-living" Ziegler-Natta polymerization and ATRP. 13 Polybutadiene (PBD) is one of the most important polymers whose properties mainly depend on their microstructures of cis21,4, trans21,4, and 1,2 isomers. Syndiotactic 1,2-PBD (s-1,2-PBD), a typical thermoplastic elastomer, is widely used as films, tubes, and hoses as well as reinforcing agents for rubbers endowing the materials with high elastic modulus, high strength, abrasive resistance, and long durability.…”

Recent progress in synthesis of stereoblock copolymers

“…Cui课题组 [39,40] Matyjaszewsi课题组 [41,42] Carpentier课题组 [43] 报道了一种合成间同-无规 两嵌段聚苯乙烯的方法, 首先采用"准活性"催化体 系 Cp*Ti(CH 2 Ph) 3 /B(C 6 F 5 ) 3 /Al(n-Oct) 3 催 化 苯 乙 烯 聚 合得到间同聚苯乙烯, 并对其进行溴化反应, 再以此 大 分 子 引 发 剂 引 发 苯 乙 烯 的 原 子 转 移 自 由 基 聚 合 (ATRP), 从而得到间同-无规两嵌段聚苯乙烯, 并与 间同聚苯乙烯和无规聚苯乙烯的混合物的结晶行为 进行了比较, 发现嵌段共聚物的结晶速度更快.…”

Syndiotactic Polystyrene‐block‐Poly(methyl methacrylate) Copolymer via Click Chemistry

“…Syndiotactic‐polystyrene‐ block ‐atactic‐polystyrene (sPS‐ b ‐aPS) copolymers were recently synthesized by Carpentier and co‐workers12 using end‐capped sPS as macroinitiator in ATRP of styrene.…”