Nafion的酸性

Nafion的酸性

我们时不时收到有关Nafion® pH值的问题。不幸的是,pH值不能被应用到Nafion上。 
pH值的定义是,“溶液的酸度或碱度;最初,现在仍然经常表示为溶液中每升相当于克的氢离子浓度负对数。”数学上pH值=  -log [H+]。

pH值的概念假定材料可溶于水(溶液)。 Nafion不溶于水。因此,它没有一个pH值。高纯度水(蒸馏水,去离子)有一个pH值= 7。这相当于一个中立的溶液,pH值= 1为非常酸性(高浓度的氢离子)和pH值= 14是非常碱性(低浓度的氢离子)。如果Nafion在水中浸泡,按此理论,水的pH值将保持不变。实际上发生的事情是水确实变成酸性,但不是因为Nafion在水里增加了H+ 。水由H20分子组成,H +离子和- OH基。Nafion吸收了 – OH基并在水中释放很多的H+导致pH值下降。 

这个问题的简单答案因此是Nafion的pH值为7。这是一个过于简单化,但希望解决对于Nafion的关注问题。我们重申,Nafion是无毒的,当与人体接触不会导致烧伤,实际上是在过去几年作为心脏起搏器电极尖端已被植入人体,以稳定心跳速率。

这种混淆,可能是与酸性一词相关。由于Nafion没有pH值,它本身不是酸性。In Lewis acid-base terms, this means that Nafion can very readily accept a free electron. This makes Nafion electrically conductive. It also makes Nafion able to stimulate certain types of chemical reactions that require removal of an electron in order to initiate the electron.

Nafion is a copolymer of two monomeric subunits: tetrafluoroethylene (Teflon®) and perfluoro-3,6-dioxa-4-methyl-7-octene sulfonic acid. The Teflon serves as a backbone, with the other monomer attached at regular intervals along the length of the Teflon chain. The other monomer ends in a sulfonic acid group. If this sulfonic acid were able to be released and dissolve into solution, it would be a strong acid. However, Nafion is extremely resistant to chemical attack (corrosion-resistant) and the sulfonic acid cannot be broken from the Nafion, even by very strong chemical reactions. While firmly bound within the Nafion matrix, the sulfonic acid is harmless.

This is very similar to many other plastics. Many plastics contain cyanide or other poisonous chemical groups. Once polymerized into solid plastic, however, these potentially hazardous groups are permanently bound, and are no longer harmful.

我们时不时收到有关Nafion® pH值的问题。不幸的是,pH值不能被应用到Nafion上。 
pH值的定义是,“溶液的酸度或碱度;最初,现在仍然经常表示为溶液中每升相当于克的氢离子浓度负对数。”数学上pH值=  -log [H+]。 


pH值的概念假定材料可溶于水(溶液)。 Nafion不溶于水。因此,它没有一个pH值。高纯度水(蒸馏水,去离子)有一个pH值= 7。这相当于一个中立的溶液,pH值= 1为非常酸性(高浓度的氢离子)和pH值= 14是非常碱性(低浓度的氢离子)。如果Nafion在水中浸泡,按此理论,水的pH值将保持不变。实际上发生的事情是水确实变成酸性,但不是因为Nafion在水里增加了H+ 。水由H20分子组成,H +离子和- OH基。Nafion吸收了 – OH基并在水中释放很多的H+导致pH值下降。 


这个问题的简单答案因此是Nafion的pH值为7。这是一个过于简单化,但希望解决对于Nafion的关注问题。我们重申,Nafion是无毒的,当与人体接触不会导致烧伤,实际上是在过去几年作为心脏起搏器电极尖端已被植入人体,以稳定心跳速率。


这种混淆,可能是与酸性一词相关。由于Nafion没有pH值,它本身不是酸性。相反Nafifion中保留的化合物,请使用下面的下拉菜单获取信息。