Synthesis and crystallization behavior study of syndiotactic polystyrene‐g‐isotactic polypropylene (sPS‐g‐iPP) graft copolymers
Synthesis and crystallization behavior study of syndiotactic polystyrene‐g‐isotactic polypropylene (sPS‐g‐iPP) graft copolymers
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DOI：
10.1002/pola.24706
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发表时间：
2011-06
期刊：
影响因子：
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通讯作者：
Huahua Huang;H. Niu;Jin‐Yong Dong
中科院分区：
文献类型：
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作者：
Huahua Huang;H. Niu;Jin‐Yong Dong
仅基于配位聚合机理，通过两步催化反应合成了具有间规聚苯乙烯主链和等规聚丙烯侧链的新型立构规整接枝共聚物（sPS-g-iPP）。首先，由苯乙烯衍生物、1,2-双(4-乙烯基苯基)乙烷和氢组成的链转移配合物在rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2和MAO介导的丙烯聚合中引发链转移反应，得到带有末端苯乙烯基的iPP大分子单体(iPP-t-St)。然后不同分子量的iPP-t-St大分子单体在典型的单茂钛催化剂(CpTiCl3/MAO)上在不同条件下进行间规苯乙烯聚合，生成不同结构的sPS-g-iPP接枝共聚物。通过有效的纯化过程，获得了结构明确的 sPS-g-iPP 共聚物，然后对其进行差示扫描量热法 (DSC) 和偏光光学显微照片 (POM) 研究。接枝共聚物通常具有双熔融温度和结晶温度，这分别归因于 sPS 主链和 iPP 接枝。然而，研究表明，这两个片段表现出与 sPS 均聚物和前体 iPP-t-St 大分子单体截然不同的熔融和结晶行为。因此，与各自的组分相比，接枝共聚物表现出许多独特的结晶形态。 © 2011 Wiley periodicals, Inc. J Polym Sci Part A：Polym Chem，2011。
Based on coordination polymerization mechanism only, novel stereoregular graft copolymers with syndiotactic polystyrene main chain and isotactic polypropylene side chain (sPS-g-iPP) were synthesized via two steps of catalytic reactions. First, a chain transfer reaction was initiated by a chain transfer complex composed of a styrene derivative, 1,2-bis(4-vinylphenyl)ethane, and hydrogen in propylene polymerization mediated by rac-Me2Si[2-Me-4-Ph(Ind)]2ZrCl2 and MAO, which gave iPP macromonomer bearing a terminal styryl group (iPP-t-St). Then the iPP-t-St macromonomers of varied molecular mass were engaged in syndiospecific styrene polymerization over a typical mono-titanocene catalyst (CpTiCl3/MAO) under different conditions to produce sPS-g-iPP graft copolymers of varied structure. With an effective purification process, well-defined sPS-g-iPP copolymers were obtained, which were then subjected to differential scanning calorimetry (DSC) and polarized optical micrograph (POM) studies. The graft copolymers were generally found with dual melting and crystallization temperatures, which were ascribable respectively to the sPS backbone and iPP graft. However, it was revealed that the two segments displayed largely different melting and crystallization behaviors than sPS homopolymer and the precursory iPP-t-St macromonomer. Consequently, the graft copolymer exhibited much distinctive crystalline morphologies when compared with their individual components. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.