  A two-dimensional square-lattice model for the formation of secondary
structures in proteins, the hydrogen-bonding model, is extended to include the
effects of solvent quality. This is achieved by allowing
configuration-dependent nearest-neighbour interactions. The phase diagram is
presented, and found to have a much richer variety of phases than either the
pure hydrogen-bonding self-avoiding walk model or the standard $\Theta$-point
model.
