  The recent discovery of fractional quantum Hall states in graphene raises the
question of whether the physics of graphene and its bilayer offers any
advantages over GaAs-based materials in exploring strongly-correlated states of
two-dimensional electrons. Here we propose a method to continuously tune the
effective electron interactions in graphene and its bilayer by the dielectric
environment of the sample. Using this method, the charge gaps of prominent FQH
states, including \nu=1/3 or \nu=5/2 states, can be increased several times, or
reduced all the way to zero. The tunability of the interactions can be used to
realize and stabilize various strongly correlated phases in the FQH regime, and
to explore the transitions between them.
