We develop new polyether structures for medical and pharmaceutical purposes. A recent key development are non-immunogenic "rPEGs" that are based on isomerizing the chain structure of polyethylene glycol (PEG). Intense research efforts are dedicated to multiblock architectures and to the control and understanding of monomer gradients in copolymer architectures. This feature possesses key relevance for materials properties, but also for copolymers at the biological interface.