在玻璃成型聚乙烯矩阵中可变大小的两添加剂的扩散系数
María Del Mar Cammarata1, Mario D Contin2, R Martín Negri1
1Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires C1428EHA, Argentina.
The journal of physical chemistry. B
|December 25, 2023
概括
使用分子动力学模拟来预测聚合物添加剂扩散有助于尽量减少实验. 这项研究揭示了聚乙烯矩阵中的扩散行为,受矩阵特性和温度的影响,为增材运输提供了洞察力.
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
- 计算化学计算化学
背景情况:
- 在聚合物中添加剂的扩散对于定制复合材料特性至关重要.
- 预测附加扩散行为可以减少实验成本和时间.
研究的目的:
- 用分子动力学模拟来估计聚乙烯 (PE) 矩阵中的添加剂的自我扩散系数 (D).
- 研究PE矩阵特性和温度对增材扩散机制的影响.
主要方法:
- 微秒时间尺度分子动力学模拟利用MARTINI力场.
- 描述PE矩阵的特性,包括玻璃过渡温度 (Tg).
- 对扩散系数对添加物分子质量和温度的依赖性的分析.
主要成果:
- 扩散系数受到PE矩阵玻璃形成特性 (Tg = 256-260 K) 的显著影响.
- 在高温下观察到类似于Rouse的扩散,在PE转移稳定区域内偏离.
- 扩散系数对相似大小的添加剂的极点头不敏感.
- 温度依赖的扩散在高温下遵循阿雷尼乌斯的行为,在低温下遵循超级阿雷尼乌斯的趋势,由能量景观解释.
结论:
- 聚合物矩阵的移动性对溶液的自我扩散产生了重大影响.
- 确定了在高温下对PE中的大型添加剂进行粗粒度 (CG) 和全原子模拟之间的时间等价性.
- 这项研究为了解聚合物矩阵中的超阿雷尼乌斯扩散行为提供了一个概念框架.
更多相关视频
相关概念视频
Extraction: Partition and Distribution Coefficients
2.4K
The distribution law or Nernst's distribution law is the law that governs the distribution of a solute between two immiscible solvents. This law, also known as the partition law, states that if a solute is added to the mixture of two immiscible solvents at a constant temperature, the solute is distributed between the two solvents in such a way that the ratio of solute concentrations in the solvents remains constant at equilibrium.
For extracting a solute from an aqueous phase into an...
For extracting a solute from an aqueous phase into an...
2.4K
Factors Affecting Dissolution: Drug pKa, Lipophilicity and GI pH
1.4K
Drug absorption within the gastrointestinal (GI) tract is a complex process influenced by several critical factors, including the site pH, the drug's dissociation constant (pKa), and the drug's lipophilicity. The GI tract exhibits a pH gradient, with an acidic environment in the stomach and a more alkaline environment in the small intestine. This pH variation directly affects the ionization state of drugs.
A drug's pKa and the pH of the gastrointestinal (GI) tract play crucial roles...
A drug's pKa and the pH of the gastrointestinal (GI) tract play crucial roles...
1.4K
Factors Affecting Activity Coefficient
802
The extended Debye-Hückel equation indicates that the activity coefficient of an ion in an aqueous solution at 25°C depends on three partially interdependent properties: the ionic strength of the solution, the charge of the ion, and the ion size.
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a...
The activity coefficient value for an ion is close to one when the solution has almost zero ionic strength, i.e., when the solution shows close to ideal behavior. As the ionic strength of the solution increases from 0 to 0.1 mol/L, a...
802
Polymers: Molecular Weight Distribution
3.4K
For any given polymer, the weight average molecular weight (Mw) is higher than, if not equal to, the number average molecular weight (Mn). The only situation in which the weight average molecular weight and the number average molecular weight are equal is when a polymer consists only of chains with equal molecular weight. However, this never happens in a synthetic polymer, since it is difficult to control the polymerization process up to a molecular level with accuracy to a hundred percent.
3.4K
Passive Diffusion: Overview and Kinetics
483
Passive diffusion is a critical process that allows small lipophilic drugs to cross the cell membrane along a concentration gradient. This mechanism's efficiency depends on four primary factors: the membrane's surface area, the drug's lipid-water partition coefficient, the concentration gradient, and the membrane's thickness.
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting...
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting...
483
Diffusion
192.5K
Diffusion is the passive movement of substances down their concentration gradients—requiring no expenditure of cellular energy. Substances, such as molecules or ions, diffuse from an area of high concentration to an area of low concentration in the cytosol or across membranes. Eventually, the concentration will even out, with the substance moving randomly but causing no net change in concentration. Such a state is called dynamic equilibrium, which is essential for maintaining overall...
192.5K


