Sciencemadness Discussion Board

Etching PTFE for subsequent bonding

Quince - 4-10-2005 at 23:15

There are a number of commercial sodium-based etchants. What I'm wondering is if there's any way to DIY using OTC stuff.

[Edited on 5-10-2005 by Quince]

bio2 - 6-10-2005 at 21:39

Maybe NaOEt from NaOH & EtOH.

vulture - 7-10-2005 at 02:05

Hmm, apparently some solvents can "bloat" teflon, that is the gaps between the polymer strands are widened. I wonder if this could provide any means for bonding something to it.

Nerro - 7-10-2005 at 06:15

Quote:
Originally posted by bio2
Maybe NaOEt from NaOH & EtOH.
To my knowledge NaEtO is made by letting Na(s) react with absolute-EtOH(l) and not by letting EtOH and NaOH react. (NaEtO is a stronger base than NaOH so the reaction you propoese would not work in water)

countrychemist - 7-10-2005 at 07:31

NaEtO can be made by NaOH(s) + EtOH(l) I would of course use lab grade 190 proof for this though. I make KMeO on a regular basis by KOH + MeOH. It's fairly simple to make. Maybe KEtO may be a better choice..KOH dissolves in these solvents much better than NaOH

mick - 7-10-2005 at 11:22

I am interested in making alcoxides with base plus alcohol
I have made NaOEt by dissolving Na in EtOH with H2 evoled. NaOH dissolves in EtOH, MeOH etc with no H2. I always though it was through the alcohol solvating the OH part which solubilises the Na. Depending on the concentrations you could have all sorts of complexes but I did not think that you would make the ethoxide.
mick

countrychemist - 7-10-2005 at 11:28

The Methoxide or Ethoxide that I make is fairly simple....I use it as a catalyst for the transesterification of tryglycerides to make fatty acid methyl or ethyl esters (biodiesel). I know that I've never had a problem with it.

biodiesel link --> www.journeytoforever.org

CD-ROM-LAUFWERK - 7-10-2005 at 12:02

i thought a moderator say this, but this is only organic chemistry, isnt it? ;)

Eclectic - 7-10-2005 at 14:22

I'm fairly sure that the commercial etchant is an adduct of sodium and naphthaline in toluene. Lithium from a lithium batery would probably work. Another method is high voltage corona discharge.

Quince - 8-10-2005 at 05:04

Quote:
Originally posted by vulture
Signature:
"Every gun that is made, every warship launched, every rocket fired, signifies in the final sense a theft from those who hunger and are not fed, those who are cold and are not clothed."
President Dwight D. Eisenhower

Yeah, but feeding and clothing people is boring. I'd rather be firing rockets.



In any case, people are hungry and cold because there are too many of them. More rockets = less people.

[Edited on 8-10-2005 by Quince]

vulture - 8-10-2005 at 07:55

What the? Let's keep this on topic, shall we? Before I start massively deleting posts.

Quince - 8-10-2005 at 18:16

Sorry. Of course that was a joke. But I figured that given the fact that mick already threadjacked here with his "I am interested in making alcoxides with base plus alcohol", we had completely gotten off-topic anyway...

In any case, I mixed ethanol that I had gotten by vigreux distillation from 151 proof rum with sodium lye, and dipped the teflon for a while, and nothing happened...

bio2 - 8-10-2005 at 23:07

........In any case, I mixed ethanol that I had gotten by vigreux distillation from 151 proof rum with sodium lye, and dipped the teflon for a while, and nothing happened... ............

Unfortunately it's not quite that simple, lol.

The dupont website has different teflon etchant formulas that led me to believe that sodium ethoxide or methoxide might work.
Methanol is easy to get in dry form as well.

Quince - 9-10-2005 at 00:22

Nothing's dry here. The closest is 99% isopropanol. From burning test, my ethanol seems above 95%.

[Edited on 9-10-2005 by Quince]

Eclectic - 9-10-2005 at 07:47

Naphthaline in toluene with alkali metal.
Blue charge transfer complex. Strips fluorine from PTFE surface.

Quince - 9-10-2005 at 15:51

OK, but where to get the alkali metal?

Eclectic - 9-10-2005 at 16:38

http://www.erowid.org/archive/rhodium/chemistry/lithium.batt...

Quince - 9-10-2005 at 18:22

So I just mix it with toluene and naphthalene?

Eclectic - 10-10-2005 at 04:59

I'd try putting some of the Li foil in a solution of 10% naphthaline in toluene.
If you get a dark blue solution, that should do it. Keep tightly closed or make just before use in very small amounts.
I've never done this, so be carefull.
I'd use sodium, since I have some. Li might not be reactive enough.