Dear Ali,

controll over the Pi-Pi stacking in the preperation of GO or RGO is still challenging in order to get the single or few layers of graphene, in solid state. RGO has hydrophobic nature, when you disperse in aquous media you will have few no. of layers... during the process of drying these layers are restacking, resulting thicker films of graphene.

I suggest you to use any surface passivation agents such as PEG depending upon the molecular weight, you can use PEG 1500N.. these are basically polymers, hydrophilic, act like a suface binders so that you do not have much electrostatic interaction or pi-pi stacking b/w the grahene intrlayers after the exfoliation...

There are some reviews in Advanced Materials... you can see that..

Dear Ravi

Thanks for your comment but state of grahene layers in dry state doesn't matter for me, as i noted my samples couldn't redisperse in water or DMF after drying, would you please address those reviews you mentioned above

After "vaccum drying", your sample should redisperse in DMF.. try at low concentrations. Better will be using solvents like NMP or DMSO instead of DMF.

After freeze-drying, you will receive a graphene foam. It can be dispersed in water or DMF.