The dual-cure thiol-ene-epoxies, or OSTE+ polymers, differ from the OSTE-polymers in that they have two separated curing steps. After the first UV-initiated step, the polymer is rubbery and can easily be deformed Hansson, Proc. IEEE MEMS 2014 San Francisco, (2014) and it has surface anchors available for surface modification. Zhou, Proc. MicroTAS 2013 Freiburg, (2013) During the second step, when all the thiols and epoxies are reacted the polymer stiffens and can bond to a wide number of substrates, including itself, via the epoxy chemistry. The advantages put forward for the OSTE+ are i) their unique ability for integration and bonding via the latent epoxy chemistry and the low built-in stresses in the thiol-enes polymers ii) their complete inertness after final cure iii) their good barrier properties Saharil, Journal of Micromechanics and Microengineering 23, 025021 (2013) and the possibility to scale up manufacturing using industrial reaction injection molding. Both stiff and rubbery versions of the OSTE+ polymers have been demonstrated, showing their potential in microsystems for valving and pumping similar to PDMS components, but with the benefit of withstanding higher pressures. The commercial version of the OSTE+ polymer, OSTEMER 322, has been shown to be compatible with many cell lines.
