Dear all,
I need to cure the PDMS @ RT (or even better at a lower temperature) since biological reactant have been encapsulated into the PDMS. Do you know how long does it take to cure the PDMS @ RT?
Thank you for your help!
Valerio
Hi Sung-Joon Cho,
Thank you for your time! Is there any mathematical relationship between curing temperature and curing time?
Than you for your help!
At ambient room temperature, you'll have to wait at least 48 hours in order not to get frustrating results.
At 75°C, I remember, I went fine with less than 5 hours curing time.
However, I'd always refer to the manufacturer's manual. For Sylgard184, it's here: http://www.dowcorning.com/DataFiles/090276fe80190b08.pdf Note that curing agent amount is key to determine final elastic strength and/or curing time.
I just played around and plotted ln(1/curing time) over 1/absolute temp (Kind of a messy Arrhenius plot). Within my linear model, I could reproduce a hypothetical 3.8 hrs curing time @ 75°C, which matches quite nice w/ the 5 hrs described above.
as sylgard:
At room temperature (20℃) ~ 48 hrs At 100℃ ~ 35 mins At 125℃ ~ 20 mins (plastic containers begin to melt higher than this temp) At 150 ℃ ~ 10 mins
be careful, as baking temperature increases, the young module of pdms also increase as Nicolas Liem said baking at 60-80°C for 3 to 4 hr is optimum
Sometimes the cured PDMS remains sticky after 48 hours. I usually keep it at room temperature (25 ℃ ) for initial 12 hour and then for 12 hours at 60 ℃ . Very nice sheets are obtained with thickness upto 3mm..Well cured!! The temperature equal to 60 ℃ is not high enough to destroy your encapsulated biological samples, what I feel.
There are many variables affecting the curing of PDMS (elastomers) @ 25c.
Assuming the curing is via hydrosilylation, platinum type and amount, inhibitor level, crosslinker reactivity to name a few. Uninhibited elastomers will cure in seconds at room temperature or will remain uncured for months with a tuned platinum inhibitor combination.
This attachment gives specific information about SYLGARD 184 PDMS. Curing times for different temperatures as well as room temperature are given. I have tried a few of these temperatures and corresponding curing times in the past and got fully cured PDMS.
https://www.dow.com/content/dam/dcc/documents/en-us/productdatasheet/11/11-31/11-3184-sylgard-184-elastomer.pdf?iframe=true
If RT means 25 C, 48 hrs. If 20 C, wait 72 hrs. More info here: researchmicrostamps.com/resources
Mixing ratio is10:1 with a thickness 6 mm, 70C for 4 hours, works for me pretty good.
The mixing ratio is10:1 with a thickness of 3 mm, 90 C for 2 hours. It works.
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