I dont think that this is possible without additional adhesives. I believe you mean cross-linked PDMS? Glasstransition of PDMS is at -125°C. Non-cross-linked PDMS is a liquid at RT and decomposes at ~200°C. Besides that, PDMS is very nonpolar (~21mN/m purely dispers) and PMMA is very polar (~35mN/m dispers and ~10mN/m polar). As they wont form intermolecular bonding there will be no adhesive bond between the two.

Martin Wortmann sir, thanks for your previous response.

So, you mean, that PDMS can't be cross-linked with PMMA. Can you please provide some examples of adhesives that can be used to bond/stick the two polymers without affecting their individual tensile/mechanical strength?

I am not an expert in adhesives. It's not entirely clear to me if your PDMS film is already cross-linked or if you are trying to synthesize or deposit the films on each other?... generally adhesion to PDMS is challenging, but I believe there are commercially available primers/adhesive systems.

Martin Wortmann thanks for your previous reply,

Yes, the PDMS is already crosslinked and polymerized, thus making a flexible polymer film out of it. I have a very thin PMMA polymer coating on top of a graphene sample and I want to bond the PDMS film to this PMMA layer.

Have you tried with any silane coupling agents?

Sushanta Sethi thanks for your previous reply.

3-aminopropyl triethoxysilane (3-APTES) can be used to bond PMMA-PDMS irreversibly.

Article The optimization of PDMS-PMMA bonding process using silane primer

Hey Mukesh,

There is an amazing paper describing PMMA bonding to different polymers. You can adjust the parameters to see how it will work for PDMS-PMMA bonding.

Article A new simple and fast thermally-solvent assisted method to b...

The Flexdym polymer created by Eden Tech is a great alternative PDMS. It's biocompatible, transparent, gas permeable and can be molded in just a couple of minutes. And it binds to a variety of substrates including PMMA. Here's a link: https://eden-microfluidics.com/