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首页> 外文学位 >Microstructure Evolution during Thermal Treatment in Block Copolymer and Block Copolymer Blend Systems.
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Microstructure Evolution during Thermal Treatment in Block Copolymer and Block Copolymer Blend Systems.

机译：嵌段共聚物和嵌段共聚物共混体系中热处理过程中的微观结构演变。

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摘要

Understanding the implications of defect structures in block copolymer (BCP) based materials is critical to realize practical applications in various emerging technologies. This thesis explores the microstructure evolution during thermal treatment in amorphous lamellar BCPs and BCP blends. A novel procedure involving film casting under controlled low-pressure conditions, reconstructive electron microscopy using serial imaging, stereology as well as pattern matching and filtering was developed to evaluate the grain growth kinetics as well as the microstructure evolution during thermal annealing. With this procedure the microstructure evolution in poly(styrene-b-isoprene) (PS-PI) as well as blends with homopolystyrene and oligo-styrene functionalized gold nanoparticles at various filling fractions was examined. Particular emphasis was on the elucidation of the texture parameters including the evolution of grain size and shape, lamellar domain orientation as well as type and extent of grain boundary structures as a function of thermal annealing times (at T=120 deg C, duration of 0, 3, and 7 days, respectively). It was found in this study that, (1) grain boundary formation can be attributed to the nucleation and growth of the microphase separated grains as well as stresses that (presumably) arise during the later stages of solvent evaporation. (2) the grain growth during thermal annealing predominantly occurs through the annealing of high angle symmetric tilt grain boundaries. (3) nano-sized additives reduce grain growth rate by stabilizing the high angle grain boundary structure. This is interpreted as a consequence of selective segregation of the fillers within grain boundary regions. In addition, with the analysis of triple junction geometry, grain boundary energy was calculated as a function of grain misorientation and determined to be strongly correlated to the angle of misorientation between adjacent grains.
机译：了解基于嵌段共聚物（BCP）的材料中缺陷结构的含义对于实现各种新兴技术的实际应用至关重要。本文探讨了非晶片状BCP和BCP共混物热处理过程中的微观组织演变。开发了一种新颖的方法，包括在受控的低压条件下进行薄膜流延，使用串行成像，立体学以及模式匹配和过滤的重建电子显微镜，以评估晶粒的生长动力学以及热退火过程中的微观结构演变。通过该程序，研究了在不同填充率下，聚苯乙烯-异戊二烯（PS-PI）以及与均聚苯乙烯和低聚苯乙烯官能化的金纳米粒子共混物的微观结构演变。特别强调的是阐明织构参数，包括晶粒尺寸和形状的演变，层状畴取向以及晶界结构的类型和程度与热退火时间的关系（在T = 120℃，持续时间为0时） ，分别为3天和7天）。在这项研究中发现，（1）晶界的形成可归因于微相分离晶粒的形核和生长，以及（可能）在溶剂蒸发后期产生的应力。 （2）热退火过程中的晶粒长大主要是通过高角度对称倾斜晶界的退火而发生的。 （3）纳米级添加剂通过稳定高角度晶界结构降低了晶粒生长速率。这被解释为填料在晶界区域内选择性偏析的结果。此外，通过分析三重结的几何形状，计算出晶界能与晶粒取向差的关系，并确定与相邻晶粒之间取向差的角度密切相关。

著录项

  • 作者

    Ryu, Hyung Ju.;

  • 作者单位

    Carnegie Mellon University.;

  • 授予单位 Carnegie Mellon University.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 202 p.
  • 总页数 202
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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