The field of functional polymers is much more diverse than that of the commonly known and successfully used “plastic” materials for all kinds of construction purposes. The development of synthetic functional macromolecular architectures from organic building blocks is very dynamic, and many fascinating biomimetic concepts are driven by possible applications in biotechnology. With the help of examples from our own research work, it is demonstrated that synthetic polymers, especially those with well-defined structures obtained from controlled polymerizations, are most versatile for the creation of a large variety of nanostructures. Ultrafiltration membranes for size-based separations of proteins and other nanoparticles can be obtained by controlled phase separation of polymer solutions. The incorporation of tailored block copolymers leads to additional functions, for instance, an ultrafiltration separation capability which can be “switched” by stimuli such as environmental conditions (e.g., pH value or temperature). The surface functionalization with grafted functional copolymers leads to materials where either the unwanted, nonspecific adsorption of proteins is very efficiently reduced (nanoscale grafted antifouling coatings), or the specific recognition of proteins can be used for fast and efficient mass separation (macroporous protein adsorbers). Beyond the described examples in membrane materials and technologies, there is a huge potential for such tailored, “smart” polymeric non-materials in sensors, microsystems, biomaterials and many other relevant fields.