Inorganic Surface Nanostructuring by Atmospheric Pressure Plasma-Induced Graft Polymerization

Abstract

Surface graft polymerization of 1-vinyl-2-pyrrolidone onto a silicon surface was accomplished by atmospheric pressure (AP) hydrogen plasma surface activation followed by graft polymerization in both N-methyl-2-pyrrolidone (NMP) and in an NMP/water solvent mixture. The formation of initiation sites was controlled by the plasma exposure period, radio frequency (rf) power, and adsorbed surface water. The surface number density of active sites was critically dependent on the presence of adsorbed surface water with a maximum observed at approximately a monolayer surface water coverage. The surface topology and morphology of the grafted polymer layer depended on the solvent mixture composition, initial monomer concentration, reaction temperature, and reaction time. Grafted polymer surfaces prepared in pure NMP resulted in a polymer feature spacing of as low as 5-10 nm (average feature diameter of about 17 nm), an rms surface roughness range of 0.18-0.72 nm, and a maximum grafted polymer layer thickness of 5.5 nm. Graft polymerization in an NMP/water solvent mixture, however, resulted in polymer feature sizes that increased up to a maximum average feature diameter of about 90 nm at [NMP] = 60% (v/v) with polymer feature spacing in the range of 10-50 nm. The surface topology of the polymer-modified silicon surfaces grafted in an NMP/water solvent mixture exhibited a bimodal feature height distribution. In constrast, graft polymerization in pure NMP resulted in a narrow feature height distribution of smaller-diameter surface features with smaller surface spacing. The results demonstrated that, with the present approach, the topology of the grafted polymer surface was tunable by adjusting the NMP/water ratio. The present surface graft polymerization method, which is carried out under AP conditions, is particularly advantageous for polymer surface structuring via radical polymerization and can, in principle, be scaled to large surfaces.

Efficient and facile one pot carboxylation of multiwalled carbon nanotubes by using oxidation with ozone under mild conditions

“…8). The data can be fitted to values close to those of graphite and more specifically, to those reported in the literature for CNTs [8,9,31].…”

“…Different techniques, such as chemical treatments using high concentration acids [2,3], sheathing, wrapping or grafting the CNTs with polymer chains [4][5][6][7] and functionalization in plasma conditions [8][9][10] have been used to improve functionalities of CNT surfaces.…”

Surface Modification of Hydrophobic PMMA Intraocular Lens by the Immobilization of Hydroxyethyl Methacrylate for Improving Application in Ophthalmology

“…Among these approaches, plasma-induced graft polymerization is an attractive way for modifying the surface chemistry and morphology of polymeric materials at low temperatures [7][8][9][10]. Chemically reactive species generated in non-thermal plasmas are favorable for both the initiation and propagation of chemical reactions and hence highly efficient surface chemistry modification [11].…”

Plasma engineered surfaces for orthopedic devices

“…The grafted polymer, covalently bound to the substrate, introduces new material properties while maintaining the physical integrity of the native surface. [16] In polymer grafting, synthesized polymers are directly grafted to the surface, whereas in graft polymerization, monomers are surface grafted and subsequently polymerized. [16,17] Both processes have been accomplished by chemical, photochemical, plasmainduced, and enzymatic grafting methods.…”

“…[16] In polymer grafting, synthesized polymers are directly grafted to the surface, whereas in graft polymerization, monomers are surface grafted and subsequently polymerized. [16,17] Both processes have been accomplished by chemical, photochemical, plasmainduced, and enzymatic grafting methods. [5,18,19] The chemical, photochemical, and radiation-based techniques can be time intensive, and often the graft polymerization or polymer grafting is difficult to achieve uniformly due to the limited availability of surface hydroxyl groups or anchoring sites.…”