Described herein are methods for chemical modification of nitrocellulose to generate lyophobic properties which are useful in propellant compositions. Such methods include the steps of: a) dissolving neat nitrocellulose in an organic solvent; b) adding a silyl based isocyanate and a catalyst to the solution; (d) stirring the solution in a moisture free environment; e) hydrolyzing the solution by exposing said solution to moisture; and (e) adding fluorinated oxysilane. The modified nitrocellulose retains its energetic properties while exhibiting high water and organic solvent phobicity, effectively functioning as a barrier to migration or diffusion of liquid components in propellant compositions.