WARNING! This idea/possibility has been moved to the talk page in Manipulated spacetimes because it is unlikely and not really predicted by the theory it is based on. See manipulated spacetimes for a more probable idea/possibility.
The Casimir effect occurs when extremely thin (a few micrometres or thinner) plates of some materials (gold leaf are typically used, but graphene may possibly be more efficient) are placed extremely close to each other (a few micrometres or less apart). The plates approach each other if they are not prevented from moving. One practical application for space travel (and better launches) are explained in manipulated spacetimes, section ideas and possibilities. The workforce should test if graphene can generate a Casimir effect and edit the result into manipulated spacetimes, section The Casimir effect under Ideas and possibilities. Some fools on wikipedia are deleting all information about the Casimir effect from their article about graphene!
One possibility to create the necessary graphene "sandwich" would be to expose carbon in zero gravity to a interference pattern of electromagnetic waves with the same wavelength as the diameter of a carbon atom, which means x-rays of a somewhat less energetic wavelength than in an ordinary x-ray scan. The constructive and destructive interference would then, due to the weightlessness, organize the carbon atoms into graphene layers spaced the width of one carbon atom apart, a perfect Casimir sandwich.