Surface modification of substrates

A smart material comprising:

• a substrate defining a surface wherein the substrate is formed from a substrate material;
• a cross-linked polymeric anchoring layer bonded directly to the substrate material at the substrate surface, wherein the anchoring layer comprises polymers having a molecular weight of at least about 2000 bound directly to the substrate material at the substrate surface at multiple points along each polymer and cross-linked at multiple points along the length of each polymer, wherein the anchoring layer has a graft density on the substrate surface of at least about 0.3 chains per square nanometer;
• a first material grafted to the anchoring layer;
• and
• a second material grafted to the anchoring layer, wherein the first material and the second material display a response different from one another upon application of a known stimulus.