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Synthesis, characterization and properties of model PCHE/PE block copolymers.

机译：PCHE / PE嵌段共聚物模型的合成，表征和性能。

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摘要

Hydrogenated polystyrene (also known as polycyclohexylethylene, PCHE) has many material properties superior to those of polystyrene such as improved thermal, oxidative and UV stability; much increased glass transition temperature and a twenty-four fold reduction in the stress optical coefficient. Coupled with the desirable light absorption spectrum, PCHE is a good candidate for replacing polycarbonate in many optical applications. However, PCHE hornopolymer is a brittle glass due to high entanglement molecular weight, which severely limits the effectiveness of the polymer. The overall toughness of PCHE has to be significantly enhanced before any practical usages.;Incorporating a ductile component into the PCHE in the form of linear block copolymer was chosen as the toughening strategy. Polyethylene (PE) from the hydrogenation of poly(1,4-butadiene) was selected as the soft block due to its excellent low temperature ductility and a refractive index nearly identical to that of PCHE. Model PCHE/PE block copolymers were synthesized via anionic polymerization followed by catalytic hydrogenation. Either sequential monomer addition or use of a bifunctional coupling agent was utilized in the synthesis of precursor block copolymers. Model PCHE/PE block copolymers with variety of linear chain architectures, ranging from diblock to pentablock, were synthesized and fully characterized.;The melting temperature and percent crystallinity of PE blocks were measured for the model PCHE/PE block copolymers under variety of material states: (1) multigrains versus single grain of block copolymer microstructures; (2) as-pressed versus strained-to-break. The orientation of PE stems with respect to the interfaces of block copolymer microstructure was probed using a model block copolymer with globally aligned lamellar microstructure. Changes in PE crystallites after tensile deformation were characterized.;The tensile mechanical properties were investigated for model PCHE/PE block copolymers with multigrains of microstructures. Anisotropic tensile mechanical properties were characterized for model block copolymers with a single grain of globally aligned lamellar microstructure. Morphological changes of block copolymer microstructures associated with the tensile deformation were probed. Key finding was the surprising improvements in tensile mechanical properties of the pentablock over analogous triblock copolymers, demonstrating the effect of block copolymer chain architecture.
机译：氢化聚苯乙烯（也称为聚环己基乙烯，PCHE）具有许多优于聚苯乙烯的材料特性，例如改进的热，氧化和紫外线稳定性；玻璃化转变温度大大提高，应力光学系数降低了二十四倍。结合所需的光吸收光谱，PCHE是在许多光学应用中替代聚碳酸酯的理想选择。然而，由于高缠结分子量，PCHE角质聚合物是脆性玻璃，这严重限制了聚合物的有效性。在任何实际使用之前，必须显着提高PCHE的整体韧性。;选择将韧性成分以线性嵌段共聚物的形式引入PCHE中作为增韧策略。由于其出色的低温延展性和几乎与PCHE相同的折射率，选择了将聚（1,4-丁二烯）氢化得到的聚乙烯（PE）作为软嵌段。通过阴离子聚合，然后催化氢化，合成了模型PCHE / PE嵌段共聚物。顺序添加单体或使用双官能偶联剂都用于前体嵌段共聚物的合成中。合成并充分表征了具有从二嵌段到五嵌段的各种线性链结构的模型PCHE / PE嵌段共聚物。;在各种材料状态下测量了模型PCHE / PE嵌段共聚物的PE嵌段的熔融温度和结晶度：（1）嵌段共聚物微观结构中的多晶粒与单晶粒； （2）压力大与断裂要紧。使用具有整体排列的层状微结构的模型嵌段共聚物探究了PE茎相对于嵌段共聚物微结构的界面的取向。表征了拉伸变形后PE微晶的变化。；研究了具有微细结构的模型PCHE / PE嵌段共聚物的拉伸力学性能。对具有整体取向的层状微结构的单晶粒的模型嵌段共聚物的各向异性拉伸机械性能进行了表征。探讨了与拉伸变形有关的嵌段共聚物微观结构的形态变化。关键发现是与类似的三嵌段共聚物相比，五嵌段共聚物的拉伸机械性能得到了令人惊讶的改善，证明了嵌段共聚物链结构的影响。

著录项

  • 作者

    Chu, Chin.;

  • 作者单位

    University of Minnesota.;

  • 授予单位 University of Minnesota.;
  • 学科 Chemistry Polymer.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 256 p.
  • 总页数 256
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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