The nanotexturing of microstructured polystyrene surfaces through CF4 plasma chemical fluorination is presented in this study. It is demonstrated that the parameters of a surface micropore-generation process, together with the setup of subsequent plasma-chemical modifications, allows for the creation of a long-term (weeks) surface-stable micro- and nanotexture with high hydrophobicity (water contact angle >150°). Surface micropores were generated initially via the time-sequenced dosing of mixed solvents onto a polystyrene surface (Petri dish) in a spin-coater. In the second step, tetrafluoromethane (CF4) plasma fluorination was used for the generation of a specific surface nanotexture and the modulation of the surface chemical composition. Experimental results of microscopic, goniometric, and spectroscopic measurements have shown that a single combination of phase separation methods and plasma processes enables the facile preparation of a wide spectrum of hierarchically structured surfaces differing in their wetting properties and application potentials.
The pseudo 3D hierarchical structure mimicking in vivo microenvironment was prepared by phase separation on tissue culture plastic. For surface treatment, time-sequenced dosing of the solvent mixture with various concentrations of polymer component was used. The experiments showed that hierarchically structured surfaces with macro, meso and micro pores can be prepared with multi-step phase separation processes. Changes in polystyrene surface topography were characterized by atomic force microscopy, scanning electron microscopy and contact profilometry. The cell proliferation and changes in cell morphology were tested on the prepared structured surfaces. Four types of cell lines were used for the determination of impact of the 3D architecture on the cell behavior, namely the mouse embryonic fibroblast, human lung carcinoma, primary human keratinocyte and mouse embryonic stem cells. The increase of proliferation of embryonic stem cells and mouse fibroblasts was the most remarkable. Moreover, the embryonic stem cells express different morphology when cultured on the structured surface. The acquired findings expand the current state of knowledge in the field of cell behavior on structured surfaces and bring new technological procedures leading to their preparation without the use of problematic temporary templates or additives.
In this paper, methods of fouling prevention and cleaning of the molds from vulcanized rubber residues are presented. The surface free energy of mold surfaces has been measured and the mold release agents were compared by measuring the force needed for the release of the form. The efficiency of sodium hydroxide solvent currently used for mold cleaning in industrial practice is compared with an acid-based solvent. The effect of the acid on the mold surface is monitored as well. The relative mass loss and the change in the surface roughness parameters Sa and Sz were evaluated during the corrosion testing in the acid at various temperatures. The mold wear during a year of use in the company, and a year of continuous acid exposure was then extrapolated for steel and stainless-steel molds. Nitric acid was significantly more effective than NaOH in dissolving rubber with full dissolution occurring after 3 h at 80 °C when stirred, losing 33 % of its initial mass, while NaOH lost only 0.3 % after 24 h. Stainless steel proved very resistant to acid corrosion at 50 °C with a calculated loss of 0.003 cm of thickness per year of submersion, while 1.7131 steel would lose 0.264 cm of thickness.
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