3/8/2007

Solvent for PDMS
Filed under: Chemistry,Engineering,General,PDMS,Technology — nobrainer @ 10:44 am

So, you’re looking for a PDMS solvent. I bet you’re having a difficult time, and mostly finding scholarly articles that you either can’t access or that don’t actually have what you’re looking for. Well I’m going to provide some summary data for a very useful paper published in 2003 by Jessamine Ng Lee, Cheolmin Park, and George M. Whitesides. In their paper, Solvent Compatibility of Poly(dimethylsiloxane)-Based Microfluidic Devices, (you may be able to access the abstract and full text versions here), they report on the efficacy of various solvents for cross-linked PDMS.

For 38 different potential solvents, they immersed their samples of cross-linked PDMS and measured the amount of swelling. Most solvents won’t dissolve PDMS. The best solvents and the measured swelling ratios are listed below, along with a few very common, but less efficacious solvents. (Below all that are the chemicals that can completely dissolve the PDMS.)


Solvent Swelling Ratio
diisopropylamine 2.13
triethylamine 1.58
pentane 1.44
xylenes 1.41
chloroform 1.39
ether 1.38
tetrahydrofuran 1.38
hexanes 1.35
trichloroethylene 1.34
n-heptane 1.34
   
toluene 1.31
benzene 1.28
acetone 1.06
ethyl alcohol (ethanol) 1.40

If you actually want to dissolve PDMS, the paper says that 3 different items will do it: dipropylamine, sulfuric acid (18.0 mol/L), and trifluoroacetic acid (13.4 mol/L). It also notes that it took 39 days for the dipropylamine to completely dissolve the PDMS. It is important to note that these processes may all take days or weeks to complete.

UPDATE [2010-03-07]: A copy of the paper I was referring to has been uploaded to Scribd.

collapse junni Says:

THANK YOU! I have been looking all over for this information. I am making microfluidic devices out of PDMS, and I am ending up with cured PDMS all over the place. However, it is discouraging that nothing will dissolve PDMS quickly.

collapse nobrainer Says:

The best advice I have is to only use items near the PDMS that you can a) clean quickly before the PDMS cures, or B) throw away.

 
 
collapse IanM Says:

What would you advise to use as a solvent to clean PDMS before it cures? (i.e. from a spinner)

 
collapse Abhinav Says:

I see that when I make a PDMS layer on a surface which was previously cleaned with acetone with the PDMS layer does not cure properly. Any ideas as to why this is happening. The surface is FR4 board

 
collapse nobrainer Says:

It has been a while since I worked with the stuff, but I don’t remember having the problem you’re having.

However, I had a problem for a while where the PDMS wasn’t curing properly. The problem turned out to be related to latex gloves. Any surface I touched with latex gloves wouldn’t allow proper PDMS curing.
I don’t know what the problem was or why it happened, but nitrile gloves never caused the same behavior.

 
collapse KA Says:

Just to confirm your observation, nobrainer, I had the same problem with latex gloves, and found out that nitrile gloves are fine. Very puzzled at that time.