Using an interface displacement model derived from a microscopic density fu
nctional theory we investigate thin liquid-like wetting layers adsorbed on
flat substrates with an embedded chemical heterogeneity forming a stripe. F
or a wide range of effective interface potentials we find first-order phase
transitions as well as continuous changes between lateral interfacial conf
igurations bound to and repelled from the stripe area. We determine phase d
iagrams and discuss the conditions under which these morphological changes
arise.