短链 perfluoroalkyl carboxylic 酸和水溶液中的分子相互作用
Chris J Benmore1,2, Yuqin Wang3,4, Seth B Darling3,4
1X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont,IL 60439, USA.
概括
在水中以纳米级聚合物的形式的短链和多基物质 (PFAS). 这些结构涉及环绕 PFAS 集群的联水链,相互作用随着 PFAS 链长度的增加而增加.
科学领域:
- 环境化学环境化学
- 材料科学 材料科学 材料科学
- 物理化学 物理化学
背景情况:
- 短链多基和多基物质 (PFAS) 是令人担忧的环境污染物.
- 了解 PFAS 在水溶液中的分子相互作用对于评估它们的环境命运和影响至关重要.
- 之前的研究已经强调了PFAS在水系统中所带来的挑战.
研究的目的:
- 描述短链PFAS (CF3[CF2]nCOOH,n=1,2,3) 在水溶液中的分子相互作用.
- 为了研究由这些PFAS形成的原子和纳米长度尺度结构.
- 阐明PFAS链长度在聚合行为中的作用.
主要方法:
- 高能小和广角X射线散射 (SAXS/WAXS) 的测量.
- 短链PFAS的水溶液在10%的分子度下.
- 用于建模实验数据的经验潜力结构改进 (EPSR).
主要成果:
- 氧-氧对分布函数表明,酸氧和具有较长 PFAS 链的水分子之间的协调增加 (3.2 对于 n=1 到 4.1 对于 n=3).
- 萨克斯数据显示,长链PFAS的明显峰值 (Q1~0.2 Å−1,Q2~1.2 Å−1),随着链条的缩短而下降.
- 纳米尺度聚合被观察到为联水链的更密集的通道 (约. 20个分子) 周围的PFAS集群.
结论:
- 短链PFAS的分子相互作用和纳米级聚合高度依赖于它们的链条长度.
- 观察到的聚合结构表明PFAS分子与水之间存在复杂的相互作用.
- 这些发现为PFAS在水性环境中的行为提供了基本的见解.
相关概念视频
01:31Physical Properties of Carboxylic Acids
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Carboxylic acids with lower molecular weight exhibit a sharp and unpleasant odor. They also have higher boiling and melting points than analogous compounds, such as aldehydes, ketones, and alcohols.
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01:19Physical Properties of Carboxylic Acid Derivatives
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Among the carboxylic acid derivatives, the boiling points of acid chlorides and esters are very similar and are the lowest in the series. Acid anhydrides have slightly higher boiling...
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01:01Acid Halides to Carboxylic Acids: Hydrolysis
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Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
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01:41Reactions of Carboxylic Acids: Introduction
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01:20Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Overview
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The Fischer esterification reaction was developed by the German chemist Emil Fischer in 1895. It is a condensation reaction between carboxylic acids and alcohols in an acidic medium to give esters and water.
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01:13Carboxylic Acids to Esters: Acid-Catalyzed (Fischer) Esterification Mechanism
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Carboxylic acids react with alcohols to yield esters via an acid-catalyzed condensation reaction called Fischer esterification. This is a nucleophilic acyl substitution reaction that proceeds via a tetrahedral intermediate, where a water molecule is eliminated as the leaving group.
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