Mister Junk Pile - 2-8-2011 at 19:32
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.
Mister Junk Pile - 3-8-2011 at 15:34
Damn, this stuff is boring, eh?