The present invention provides for compositions of hyaluronic acid cross-linked with at least one other hydrophobic polymer to form a copolymer gel. The preferred composition is a formulation containing hyaluronic acid or its derivatives and a silicone base polymer with a functional group capable of reacting with the preferred cross-linker. The silicon may also be a group capable of undergoing further polymerization, or a silicone moiety adding to the hydrophobic nature of the gel. The product can be used alone or contain various other substances or covalently bound substances for numerous useful applications including cosmetic, medical, and drug delivery applications. The present invention also provides processes for preparing them.