We consider conformational transitions of the coil to flower type that occur for polymer chains attached to a surface. We use a slit geometry to impose a confinement force on an end-grafted Gaussian chain and account for the effects of the interaction of the chain with the surfaces. In the repulsion mode, that is, when the adsorption parameter c < 0, a classical first-order escape transition is found, which is significantly modified near the critical condition (c approximate to 0). When c = 0, the surface is "invisible" and no conformational transitions takes place. In the adsorption mode (one surface remains c < 0 but the other one c > 0), a bridging transition appears when the surfaces are still far apart. In addition, we discuss positional transitions that may occur when one surface is homogeneous and near critical (c approximate to 0) and the other surface is heterogeneous, that is, having patches with different affinity for the chains. In this case it is feasible that the chain assumes flowerlike conformations without physically escaping from the confined region. An AFM with a polymer probe can be used to characterize polymer-surface interactions and corresponding surface heterogeneity.