有限聚合物链的静电相关自由能量
1Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA. jdhorne@stanford.edu.
Soft matter
|September 1, 2025
概括
有限分子大小显著影响多电解质溶液,引入静电相关自由能量 (ECF) 终端效应. 这一发现完善了不同分子量聚合物的热力学建模.
科学领域:
- 物理化学
- 聚合物科学
- 热力学
背景情况:
- 静电相关自由能量 (ECF) 对于模拟多电解质溶液热力学至关重要.
- 之前的估计主要使用爱德华兹近似,
- 对于有限分子大小效应的无限链近似的局限性尚未完全理解.
研究的目的:
- 研究有限分子大小对多电解质溶液的静电相关自由能量 (ECF) 的影响.
- 为ECF导出新的闭式表达式,以考虑分子大小.
- 分析有限尺寸对热力学属性的影响,如相图和表面张力.
主要方法:
- 在多电解质溶液中的静电相互作用的理论分析.
- 自由能量贡献的推导,区分局部终端效应和长波长贡献.
- 开发用于卷状和棒状多电解质的封闭式表达式.
主要成果:
- 对ECF的主要有限分子大小贡献是N-1级,这是链末的局部效应,独立于碎形维度.
- 波长较长的贡献较弱,扩展为N^{-3/d) ln N.
- 用于各种多电解质构成和离子条件的自由能量得出了新的表达式.
结论:
- 有限的分子大小为ECF带来了以前被低估的重要贡献,特别是链末端.
- 衍生的闭式表达式为多电解质提供了更准确的热力学模型.
- 终端效应明显影响宏观性质,例如相位行为,表面张力和分区.
相关概念视频
Potential Due to a Polarized Object
470
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
470
Coulomb's Law
10.0K
Experiments with electric charges have shown that if two objects each have an electric charge, they exert an electric force on each other. The magnitude of the force is linearly proportional to the net charge on each object and inversely proportional to the square of the distance between them. The direction of the force vector is along the imaginary line joining the two objects and is dictated by the signs of the charges involved.
Newton's third law applies to the Coulomb force — the...
Newton's third law applies to the Coulomb force — the...
10.0K
Induced Electric Dipoles
4.4K
A permanent electric dipole orients itself along an external electric field. This rotation can be quantified by defining the potential energy because the external torque does work in rotating it. Then, the potential energy is minimum at the parallel configuration and maximum at the antiparallel configuration. While the former is a stable equilibrium, the latter is an unstable equilibrium.
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...
4.4K
Electrostatic Boundary Conditions in Dielectrics
1.4K
When an electric field passes from one homogeneous medium to another, crossing the boundary between the two mediums imparts a discontinuity in the electric field. This results in electrostatic boundary conditions that depend on the type of mediums the field propagates through.
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's...
Consider a case where both the mediums across a boundary are two different dielectric materials. Recall that the electric field and electric displacement are proportional and related through the material's...
1.4K
Van der Waals Interactions
66.3K
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.
66.3K
Intermolecular Forces
61.0K
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen...
61.0K


