高分子量块共聚合物的合成及其在固态中组装成有序形态
1Department of Chemistry, 423K Chemistry Building, University of Iowa, Iowa City, Iowa 52242, USA.
Journal of the American Chemical Society
|August 10, 2007
概括
研究人员合成了高分子量块共聚合物,在没有添加剂的情况下实现了超过200nm的有序结构. 这些新的聚合物架构为自组装材料提供了新的可能性.
科学领域:
- 聚合物化学 聚合物化学
- 材料科学 材料科学 材料科学
- 纳米技术纳米技术
背景情况:
- 块共聚合物对于自组装成有序纳米结构至关重要.
- 在有序聚合物形态学中实现大域大小 (>100 nm) 通常需要添加剂.
- 控制聚合物架构是调整自组装特性的关键.
研究的目的:
- 开发一种用于高分子量块共聚物的简单合成方法.
- 研究这些新型聚合物的固态自我组装到有序形态.
- 将块共聚合物的组装行为与线性块共聚合物的组装行为进行比较.
主要方法:
- 两步合成利用环开放型转化聚合和原子转移基聚合.
- 使用确保低多聚分散性的技术对聚合物进行表征.
- 通过溶剂蒸发和热回火诱导的固态组件.
- 通过扫描电子和光学显微镜进行形态分析.
主要成果:
- 成功合成了分子重量>1,000,000 g/mol的块共聚合物.
- 形成有序形态 (球形,叶片形,圆柱形),域大小在132至258nm之间,没有添加剂.
- 组装材料对光反射的证明,可通过溶剂膨胀调节.
结论:
- 块共聚合物可以在没有添加剂的情况下在固态中实现大域有序形态.
- 这项工作扩大了能够进行固态组装的聚合物架构和分子重量的范围.
- 这些发现为创建具有可调节纳米结构的先进材料提供了一个新的平台.
相关概念视频
Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
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...
Coordination Compounds and Nomenclature
In most main group element compounds, the valence electrons of the isolated atoms combine to form chemical bonds that satisfy the octet rule. For instance, the four valence electrons of carbon overlap with electrons from four hydrogen atoms to form CH4. The one valence electron leaves sodium and adds to the seven valence electrons of chlorine to form the ionic formula unit NaCl (Figure 1a). Transition metals do not normally bond in this fashion. They primarily form coordinate covalent bonds, a...
Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Formation of Higher-order Actin Filaments
The polymerization of G-actin monomers into filamentous F-actin is a multi-step process. Once the F-actins are formed, they can bundle together in different arrangements to form higher-order networks and regulate cellular functions. Common examples include the formation of lamellipodia and filopodia at the cell's leading edge by actin reorganization in a migrating cell. The microvilli on the brush border epithelial cells are also formed through the F-actin network.
The high-order actin networks...
The high-order actin networks...
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...


