Hello Maxine Yew ,

Can you desribe what you are trying to achieve? Is there a reason why the PDMS needs to be in contact with alkaline solution during the curing process?

Have you tried to accelerate the curing process? For example, you can increase the temperature to around 80 oC without drastically affecting the quality of the PDMS (it has a tendancy of becoming too stiff, even brittle), or you could try to slightly increase the curing agent content.

Jules

Hello Maxine Yew ,

You may find the following article useful, whereby benzophenone was added to act as a photoinitiator to create a photodefinable PDMS.

http://davidlu.net/b704946c.pdf

Best regards,

Marie Berthuel

Hello Jules Lloyd Hammond , thanks for the response.

I am trying to synthesize PDMS capsules with alkaline core. I have tried increasing the temperature but the capsules would rupture as they are not stable. I tried to cure them for a longer period of time, but they could not cure completely. Am guessing the alkaline core is somehow inhibiting the curing process.

Hello Marie Berthuel , thank you for the response.

Yes, I would give that a try.

Best,

Maxine

Benzophenone acts as a curing inhibitor when exposed to UV by producing radicals that poison the Pt curing agent. This is what makes it a "positive" photo-process.

I would guess that something in your alkaline solution is also poisoning the Pt curing agent. There are many elements and compounds that will poison Pt curing agents and no easy way around it other than eliminating those materials from the solution. Sulfur, Phosphorus, tin, mercury, silver, are some of the most notorious Pt poisons but there are plenty of others that may be lurking in your solution.

You could try encapsulation in some other PDMS friendly layer before coating with PDMS.