液晶棒卷块共聚合物的穿孔层结构
Kishore K Tenneti1, Xiaofang Chen, Christopher Y Li
1A. J. Drexel Nanotechnology Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104, USA.
Journal of the American Chemical Society
|November 3, 2005
概括
研究人员在棒卷液晶块共聚合物 (BCP) 中发现了新的四角形穿孔层. 这种独特的结构,观察到在聚乙烯块乙烯 (PS-b-PMPCS) (PS-bis[4-甲基]氧化碳) (PS-b-PMPCS) 中,由于BCP,转移相位边界.
科学领域:
- 聚合物科学 聚合物科学
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
背景情况:
- 棒-线圈块共聚合物 (BCP) 呈现出独特的自我组装行为.
- 液晶块共聚合物结合了聚合物链和液晶的特性.
- 了解BCP形态对于设计先进材料至关重要.
研究的目的:
- 研究新型棒卷液晶BCP的自我组装和结构特征.
- 为了识别和描述聚乙烯块-乙烯 (PS-b-PMPCS) 中穿孔层结构的形成和特征.
- 探索分子重量和组成对观察到的形态学的影响.
主要方法:
- 差分扫描热量计 (DSC) 用于热分析.
- 极化光显微镜 (PLM) 用于对结构的视觉观察.
- 微角X射线散射 (SAXS) 和广角X射线衍射 (WAXD) 用于结构分析.
- 传输电子显微镜 (TEM) 用于对形态的真实空间成像.
主要成果:
- 在PS-b-PMPCS中观察到一种新的四角孔层结构.
- 这种结构的形成取决于分子量,在低M和高M的样本中出现不同的组成.
- 穿孔对称性被确定为四角形,偏离典型的六角形包装.
- 穿孔的"发作"被可视化,显示结构形成的初始阶段.
- 与聚乙烯 (PS) 均聚合物混合,在特定组合物中诱导均四角孔.
结论:
- BCP的杆卷性质显著影响相位边界移动和由此产生的形态.
- 四角形穿孔层代表了液晶BCP中的新型结构图案.
- 组合控制,包括混合,提供了一条为高级应用量身定制BCP纳米结构的途径.
相关概念视频
Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
Characteristics and Nomenclature of Copolymers
Copolymers are the products obtained from the polymerization of multiple monomer species. So, in a polymer chain itself, there can be multiple repeating units that come from different monomers. The process of synthesizing a polymer from different monomer species is called copolymerization. When two monomers are involved, the polymer is known as a bipolymer. Polymers with three and four monomers are termed terpolymers and quaterpolymers, respectively. Figure 1 depicts the copolymerization of...
Polymer Classification: Crystallinity
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...


