液晶のロッドコイルブロックコポリマーの孔のある層構造
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
まとめ
研究者らは,ロッドコイル液晶ブロックコポリマー (BCP) の新型四角形孔のある層を発見した. この独特の構造は,ポリ・スチレン・ブロック・2,5-ビス[4-メトキシフェニル]オキシカルボニル) スチレン (PS-b-PMPCS) で観察され,BCPにより相境界が変化します.
科学分野:
- ポリマーサイエンスの科学
- マテリアルサイエンス 材料科学
- クリスタログラフィーです.
背景:
- 棒コイルブロックコポリマー (BCP) は,ユニークな自己組み立て行動を示します.
- 液晶ブロックコポリマーは,ポリマーチェーンと液晶の両方の性質を組み合わせています.
- BCPの形態を理解することは,高度な材料の設計に不可欠です.
研究 の 目的:
- 新しい棒コイル液晶BCPの自己組み立てと構造特性を調査する.
- ポリ・スタイレン・ブロック・2,5-ビス[4-メトキシフェニル]オキシカルボニル) スタイレン (PS-b-PMPCS) での穿孔層構造の形成を特定し,特徴づけること.
- 分子重量と組成が観察された形態学に及ぼす影響を調査する.
主な方法:
- 熱分析のための微分スキャニング熱計 (DSC).
- 構造物の視覚観察のための偏光顕微鏡 (PLM)
- 構造分析のための小角X線散射 (SAXS) と広角X線散射 (WAXD).
- モルフォロジーのリアルスペースイメージングのための伝送電子顕微鏡 (TEM).
主要な成果:
- PS-b-PMPCS.で新しい四角形の穴開いた層構造が観察されました.
- この構造の形成は分子量に依存しており,低M (w) 量と高M (w) 量で異なる組成で現れる.
- 穿孔対称性は四角形として特定され,典型的な六角形包装から逸脱しました.
- 穿孔の"発症"が視覚化され,構造形成の初期段階が示されました.
- ポリスチレン (PS) ホモポリマーとの混合は,特定の組成で均一な四角孔を誘導した.
結論:
- BCPのロッドコイル性質は,相境界のシフトとその結果生じる形態学に大きな影響を与える.
- テトラゴナルの孔のある層は,液晶BCPにおける新しい構造モチーフを表しています.
- 混合を含む組成制御は,BCPナノ構造を高度なアプリケーションに合わせるための経路を提供します.
関連する概念動画
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,...


