A method for the fabrication of ordered periodic nanostructures on polymeric surfaces, such nanostructures having a mound-like shape of uniformly spaced and sized protrusions of 5controlled spacing and size by means of plasma processing, which method comprises the following steps: (i) provision of a homogeneous organic polymer such as poly(methyl methacrylate) (PMMA), or Poly Ethylene Terepthalate, or Poly Ether Ether Ketone (PEEK), or Poly Styrene, or Poly Ethylene, or Cyclic Olefin Copolymer, or inorganic polymer such as Poly Dimethyl Siloxane (PDMS), or acrylic Silicon Containing polymers such as ORMOCERTM, such polymer being in the form of a plate or a film; (ii) exposure of the polymer to an etching plasma such as oxygen or sulphur hexafluoride (SF 6) or a mixture of oxygen (O 2) and sulphur hexafluoride (SF 6), or mixtures of etching gases with inert gases such as any Noble gas Ar, or He, or Ne, or Xe.; (iii) provision that the plasma reactor wall material, and/or dome, and/or electrode, and/or an intentionally inserted and biased target electrode -the target being metal or oxide, are covered with etchable materials which do not create etch inhibitors as sputtered material, optionally where such etchable wall materials may be polymeric materials; (iv) applying a bias voltage 0-100 V to the polymer sample and/or target; (v) maintaining during the plasma treatment, the electrode temperature in the range of 20 to 70 degrees Celsius below the glass transition temperature Tg of the polymer, and optionally from 30 to 60 degrees Celsius below the glass transition temperature Tg of the polymer; in which method, in the periodic nanostructures - the inverse of the Full-Width-Half-Maximum (FWHM) of the Fast-Fourier-Transform is at least equal to the wavelength of the periodic structures and preferably larger than twice 30the wavelength; - the mound-like surface of uniformly spaced and sized protrusions comprise protrusions with a height in excess of 20 nm, preferably in excess of 50 nm, and more preferably in excess of 100 nm and - the average width - of the protrusions of the nanostructures is in the range of from 10 to 400 nm, preferably 20 to 150 nm, and more preferably 20 to 100 nm. (i) provision of a homogeneous organic polymer such as poly(methyl methacrylate) (PMMA), or Poly Ethylene Terepthalate, or Poly Ether Ether Ketone (PEEK), or Poly Styrene, or Poly Ethylene, or Cyclic Olefin Copolymer, or inorganic polymer such as Poly Dimethyl Siloxane (PDMS), or acrylic Silicon Containing polymers such as ORMOCERTM, such polymer being in the form of a plate or a film; (ii) exposure of the polymer to an etching plasma such as oxygen or sulphur hexafluoride (SF 6) or a mixture of oxygen (O 2) and sulphur hexafluoride (SF 6), or mixtures of etching gases with inert gases such as any Noble gas Ar, or He, or Ne, or Xe.; (iii) provision that the plasma reactor wall material, and/or dome, and/or electrode, and/or an intentionally inserted and biased target electrode -the target being metal or oxide, are covered with etchable materials which do not create etch inhibitors as sputtered material, optionally where such etchable wall materials may be polymeric materials; (iv) applying a bias voltage 0-100 V to the polymer sample and/or target; (v) maintaining during the plasma treatment, the electrode temperature in the range of 20 to 70 degrees Celsius below the glass transition temperature Tg of the polymer, and optionally from 30 to 60 degrees Celsius below the glass transition temperature Tg of the polymer; - the inverse of the Full-Width-Half-Maximum (FWHM) of the Fast-Fourier-Transform is at least equal to the wavelength of the periodic structures and preferably larger than twice 30the wavelength; - the mound-like surface of uniformly spaced and sized protrusions comprise protrusions with a height in excess of 20 nm, preferably in excess of 50 nm, and more preferably in excess of 100 nm and - the average width - of the protrusions of the nanostructures is in the range of from 10 to 400 nm, preferably 20 to 150 nm, and more preferably 20 to 100 nm.