Polymer brushes are used as a toolbox to build up coatings by using the buttom-up principle to create the desired surface function. The used building blocks are functional linear block or comb polymers which ensure at one hand the chemical coupling to the surface and at the other hand the desired function. Such coatings can be composed by one or several different polymers to realize switching (i.e. adaption to changing environmental conditions or active switching of surface properties), to serve as optical sensor or bioactive substrate by incorporating nanoparticles or biomolecules into the layer. It is shown how multifunctionality can be used to improve easy-to clean or antifouling properties of different technical surfaces.