It depends on different factors:

1. The type of polymer you use for the study whether thermosetting polymer or thermoplastic.

2. The nature of study that you want to conduct like (a) Dynamics of phase separation, (b) crystallization and spherulitic growth (c) simple morphology.

If it is simple morphology take the sample and do the study in reflectance mode. Since graphene is black, it is difficult to do the transmittance mode.

Hi Ehssan

Please elaborate your query.

In my opinion POM is used to check surface feature in Polymer Composite area. In case of your Polymer-GO nanocomposite it is hard to see  any specific feature (particularly nano). It is beyond the limit of POM to see nano scale features. The only possibility is to see the surface of Polymer+GO.

Two ways: Microtomy preferably cryo-microtomy or direct solvent casting of your Poly/GO on microscopy slides.. 

Low concentration and well dispersed GO/Polymer composite thin film should show good transmittance..

Thank you for your answers, actually I tried to prepare it with different methods and I will try to take your suggestion my account. 

Thanks Shymaa, but I think that is away from my question and I have already done some of these. So, I wanna a different aim.