Ways to Generate Monosort Functionalized Polyolefin Surfaces

Polyolefin surfaces are characterized by their chemical inertness. To create bio-sensitive surfaces by grafting brushes, dendrimers, proteins and other biomolecules with bio-sensor properties, the presence of anchoring points at the polyolefin surface for grafting these molecules is necessary. More precisely, the existence of only one sort of functional groups in sufficient concentration at polyolefin surfaces is a precondition for chemical grafting of such bio- or polymer molecules onto these monosort groups. Several routes for introduction of monotype functional groups are based on plasma treatment. Such plasma exposure has sufficient energy to modify the inert polyolefin surfaces and introduce plasma gas-specific functional groups. However, it is well-known that plasma treatment is not selective. Therefore, special plasma processes with high selectivity in producing monotype functional groups were developed, or alternatively combinations of plasma and chemical treatments were used, or the polyolefin substrates were coated with thin layers of functional-groups bearing polymer layers produced by plasma polymerization or electrospray ionization (ESI). Grafting was preferentially performed in a wet-chemical way by nucleophilic substitution of the graft molecules onto the monotype functional groups at polyolefin surfaces. Alternatively, radical initiated graft polymerization is possible onto plasma-produced radical sites in vacuum after switching-off the plasma and immediate introduction of vapors of vinyl and acrylic monomers. However, the life-time of most plasma-produced C radicals is very short (