PS-b-PIにおけるDGとHEXの間の新しい表軸的相移行
Hae-Woong Park1, Jueun Jung, Taihyun Chang
1Department of Chemistry and Polymer Research Institute, Pohang University of Science and Technology, Pohang, 790-784, Korea.
Journal of the American Chemical Society
|December 17, 2008
まとめ
研究者は,高度なイメージングを使用してブロックコポリマーにおける相移行を研究した. 彼らは,ダブル・ジロイドが薄膜で六角形に詰め込まれたシリンダーに移行するための新しい経路を発見しました.
科学分野:
- マテリアルサイエンス 材料科学
- ポリマーサイエンスの科学
- ナノテクノロジー ナノテクノロジー
背景:
- ブロックコポリマーは,自己組み立てにより,秩序あるナノ構造を形成します.
- 薄膜形態の制御は,デバイスアプリケーションにおいて極めて重要です.
研究 の 目的:
- 二重回転管 (DG) から六角パックシリンダー (HEX) 段階への表軸相移行を調査する.
- ポリスチレン-b-ポリイソプレン二重ブロック共ポリマーの薄膜における移行経路を特徴付けるために.
主な方法:
- 牧草発生小角X線散射 (GISAXS) について.
- トランスミッション電子顕微鏡 (TEM).
- 直接3Dイメージングのための伝送電子マイクロトモグラフィー (TEMT).
主要な成果:
- DGとHEXの相場を3Dで直接観測することができました.
- DGからHEXへの新たな表頭軸の移行経路が特定されました.
- 薄膜におけるドメインの良好な指向は,観測を容易にした.
結論:
- TEMTは,共存するナノフェーズの前例のない3D視覚化を提供します.
- 特定された表軸変異経路は,誘導的自己組み立てに関する新しい洞察を提供します.
- これらの移行を理解することは,高度なナノ構造材料を製造するための鍵です.
関連する概念動画
Thermal Sigmatropic Reactions: Overview
Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in 1,5-hexadiene, referred to as...
Hybridization of Atomic Orbitals II
sp3d and sp3d 2 Hybridization
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as annulenes. In...
π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
π Molecular Orbitals of 1,3-Butadiene
Conjugated dienes have lower heats of hydrogenation than cumulated and isolated dienes, making them more stable. The enhanced stabilization of conjugated systems can be understood from their π molecular orbitals.
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...


