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Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Theoretical Explanations for the Differences in Surface Energies and Hydrophobicities of PE and PTFE?

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Mister Junk Pile

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posted on 2-8-2011 at 19:32

Theoretical Explanations for the Differences in Surface Energies and Hydrophobicities of PE and PTFE?

If this is not appropriate for this section, I apologize. I won't be hurt if it's moved.

So, I am preparing a report on the subject of surface energies and hydrophobicities of polymers when I came to the realization that I don't know for certain exactly why polytetrafluoroethylene (PTFE) has a lower surface energy and is usually more hydrophobic than polyethylene (PE) given similar surface roughness between the two.

Of course I have a rough idea: fluorine is more electronegative than hydrogen and there is thus less van der Waals interactions between H2O, H3O+ and OH- at the surface; but what are the details of this? When the more negatively charged O of H2O comes into contact with F of PTFE, it is strongly repelled. But why does the more positively charged H of H2O being attracted by the F not "cancel out" this effect? Because O is so much larger and therefore repulsion is more likely? Also, how much of a role does the greater reactivity of C-H to C- and H+ in water play in this? Is it one of the determining factors?

Hmmmmm... I guess I just simply don't understand at this level and I'm a little embarrassed because of it.

Also, any references would, of course, be greatly appreciated. I looked through a few books: Polymers at Surfaces and Interfaces by Richard A. L. Jones and Polymer Surfaces: From Physics to Technology by Fabio Garbassi to no avail. Also, Google searching didn't turn up much of anything either.

"If the freedom of religion, guaranteed to us by law in theory, can ever rise in practice under the overbearing inquisition of public opinion, then and only then will truth prevail over fanaticism." -Thomas Jefferson

Mister Junk Pile

Hazard to Self

Posts: 70
Registered: 2-7-2010
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Mood: No Mood

posted on 3-8-2011 at 15:34

Damn, this stuff is boring, eh?

Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Theoretical Explanations for the Differences in Surface Energies and Hydrophobicities of PE and PTFE?