Karen Carreon You'll need an intermediate coupling layer on the 316 stainless steel (rostfrei is one of the few German words I know!). I'd look for an epoxy primer or silane material to do this or perhaps a plasma etch. The surface will need to be scrupulously pre-cleaned before treatment. Some experimentation or literature search would be necessary, I think. There are plenty of stainless steel primers listed. Just search on 'stainless primer' and you'll come up with a bunch. Then visit your local hardware store (if you can in this Corona-regime).

BTW, because of the Montreal Protocol, I would try to find an alternative to chloroform. It's also an excellent liver and kidney poison...

Dear Dr. Karen Carreon, I suggest you to have a look at the similar question present on RG at:

https://www.researchgate.net/post/How_can_one_perform_spin_coating_of_glass_with_a_polylactide-chloroform_solution

Very interesting the answer of Dr.Tim Desmet: What is the molecular weight of your PLA ? In order to have good film-forming properties this should be sufficiently high ! Secondly, cleaning overnight in piranha, as suggested by Brian, rinsing with water and silanization in toluene is the common procedure to change surface free energy of glass substrates. Do you spincoat on glass-cover slips ? Sometimes good cleaning with desinfectol would also work for these, for other glass substrates the piranha + silanization pre-treatment is best. Furthermore, use relatively low concentrations in chloroform, not more than 3 w%. Alternatively, you could try to work from THF instead of chloroform, it takes longer to dissolve the polymer however.

Good work and best regards, Pierluigi Traverso

Dear Karen,

Please be aware of that coatings on a glass substrate and on a steel substrate are different due to the surface energy of the substrates although there are some similar processing steps. The surface of a stainless steel is normally much rougher than the surface of a glass. Secondly, the spin-coating on a stainless steel is not easy as on a glass substrate due to the thickness of the substrates too. What is the thickness of your stainless steel substrate?

I would recommend a deep coatinh method to coat your PLA solutions on your stainless steel. There is a protocol from the publication that you could follow

https://link.springer.com/chapter/10.1007/978-3-540-92841-6_330

I don't think it is easy to get homogenous films on stainless steel since myself tried various coatings on different substrates including stainless steel. The dip-coating is one of the best techniques you could apply for your application.

Alternatively, there is a simple way to use bar-coating or spray coating. In a research laboratory level, you can use a very simple tool to gain reasonably uniform films.

Hope it helps.