Molecular dynamics simulations are performed for two model pressure-sensitive adhesive (PSA) materials, atactic poly(n-butyl acrylate) [poly(n-BA)] and atactic poly(n-butyl acrylate-co-acrylic acid) [poly(n-BA-co-AA)] at a very low concentration in acrylic acid (one acrylic acid monomer per fifty butyl acrylate monomers plus three acrylic acids at each one of the two chain ends) in the bulk and confined between three crystalline substrates, silica (SiO2) represented as alpha-quartz, alpha-ferric oxide (alpha-Fe2O3), and metallic alpha-ferrite (alpha-Fe), over a range of temperatures. The simulations are carried out with the accurate, all-atom Dreiding force-field and provide important information for the distribution of local mass density of the two polymers at the three crystalline substrates, and their adsorption in conformations that lead to the formation of loop, train, and tail structures. By analyzing potential energy interactions between the two polymers and each one of the three substrates through their van der Waals contact area or by computing the diagonal elements of the local stress tensor in the vicinity of the substrate, we have calculated the effect of the type of substrate on the work of adhesion of the two polymers. Our calculations reveal a considerably stronger adsorption on alpha-quartz and alpha-ferric oxide compared to alpha-ferrite, which we attribute to strong attractive oxygen interactions of the two polymers with the oxygen atoms of SiO2 and Fe2O3. Detailed calculations of the local number density distribution of individual atomic species above the three substrates, of the local variation of the bond order parameter for skeletal and side group bonds or chords, of the distribution of dihedral angles, and of the histograms of chain ends support that the two PSAs adsorb on the three substrates with both their skeletal and pendant C-C and C-O groups lying practically parallel to the surface and in such a way that the C=O bond of the pendant butyl acrylate groups points toward the surface. The detailed MD simulations indicate that adding a small amount (7.1% wt. here) of acrylic acid to poly(n-BA) significantly improves its wetting characteristics on oxygen-containing substrates. This is in full support of the findings of Kisin et al. [Chem. Mater. 2007, 19, 903-907] that introducing oxygen atoms to a metallic surface or to polymer molecules increases considerably the work of adhesion.