The physical properties of the membrane will put limits on your ability to process an overmold. Care would also need to be taken to preserve the permeability of the membrane (avoid mold releases etc.) You could take a look at either casting/potting encapsulation with a suitable material as well. If you can do this within the "operational environment limits" for the membrane, you have a good chance at not changing it's properties. Of course I would highly recommend testing to verify any process chosen.
Regards,