Adsorption and Pattern Recognition of Polymers at Complex Surfaces with Attractive Stripelike Motifs

We construct the complete structural phase diagram of polymer adsorption at substrates with attractive stripelike patterns in the parameter space spanned by the adsorption affinity of the stripes and temperature. Results were obtained by extensive generalized-ensemble Monte Carlo simulations of a generic model for the hybrid organic-inorganic system. By comparing with adhesion properties at homogeneous substrates, we find substantial differences in the formation of adsorbed polymer structures if translational invariance at the surface is broken by a regular pattern. Beside a more specific understanding of polymer adsorption processes, our results are potentially relevant for the design of macromolecular pattern recognition devices such as sensors.

Figure 1

Polymer near a substrate with a stripe pattern; the surface is located at $z=0$. The density plot represents the periodic surface potential. The steric wall at $z=60$ regularizes the translational entropy in the half-space $z>0$.

Figure 2

Hyperphase diagrams of structural polymer phases for homogeneous substrates (top) with ${\epsilon }_{\text{stripe}}=0$ and for substrates with the stripe pattern (bottom), where ${\epsilon }_s=1$. In $A$ ($D$) phases, polymer structures are preferably adsorbed (desorbed). The second letter indicates increasing order in these phase regions: expanded ($E$), globular ($G$), and compact ($C$); PC is short for “phase coexistence.” Temperatures $T$ are given in units of $ϵ/k_{\mathrm{B}}$.

Figure 3

Examples of typical conformations in the different structural phases for homogeneous (${\epsilon }_{\text{stripe}}=0$) and striped substrates (with ${\epsilon }_s=1$).