Gelatin, one of the most abundant, naturally derived biomacromolecules from collagen, is widely applicable in food additives, cosmetic ingredients, drug formulation, and wound dressing based on their non-toxicity and biodegradability. In parallel, polyvinyl alcohol (PVA), a synthetic polymer, has been commonly applied as a thickening agent for coating processes in aqueous systems and a major component in healthcare products for cartilage replacements, eye lubrication, and contact lenses. In this study, a new type of mixed hydrogel nanofiber was fabricated from gelatin and polyvinyl alcohol by electrospinning under a feasible range of polymer compositions. To determine the optimal composition of gelatin and polyvinyl alcohol in nanofiber fabrication, several key physicochemical properties of mixed polymer solutions such as viscosity, surface tension, pH, and electrical conductance were thoroughly characterized by a viscometer, surface tensiometer, water analyzer, and carbon electron probe. Moreover, the molecular structures of polymeric chains within mixed hydrogel nanofibers were investigated with Fourier-transform infrared spectroscopy. The morphologies and surface elemental compositions of the mixed hydrogel nanofibers were examined by the scanning electron microscope and energy-dispersive X-ray spectroscopy, respectively. The measurement of water contact angles was performed for measuring the hydrophilicity of nanofiber surfaces. Most importantly, the potential cytotoxicity of the electrospun nanofibers was evaluated by the in vitro culture of 3T3 fibroblasts. Through our extensive study, it was found that a PVA-rich solution (a volumetric ratio of gelatin/polyvinyl alcohol <1) would be superior for the efficient production of mixed hydrogel nanofibers by electrospinning techniques. This result is due to the appropriate balance between the higher viscosity (~420–~4300 10⁻² poise) and slightly lower surface tension (~35.12–~32.68 mN/m²) of the mixed polymer solution. The regression on the viscosity data also found a good fit by the Lederer–Rougier’s model for a binary mixture. For the hydrophilicity of nanofibers, the numerical analysis estimates that the value of interfacial energy for the water contact on nanofibers is around ~−0.028 to ~−0.059 J/m².

A plasma system attached with one internal coil (for generating inductively coupled plasma) and two sputtering carbon targets was set up to deposit PP-MMA (plasma polymerized methyl methacrylate) thin films. PP-MMA was used as a model material in the present study. In the experiment, the working pressure and Ar/MMA flow ratio were varied, which resulted in the change in plasma conditions as well as the deposition rates. The optical emission spectroscopy (OES) method was applied to identify the presence of the excited species related to the fragmented monomer. In addition, the electron temperature and electron density were determined using the modified Boltzmann plot and line-ratio method, according to the measured OES spectra. The deposition rate of the PMMA film was then correlated with the determined plasma characteristics. To determine the vibrational modes of the deposited PP-MMA films, Fourier transformed infrared spectrometry (FTIR) was used. The highest deposition rate of PP-MMA could be obtained with the optimized working pressure and Ar/MMA volume ratio. This could be related to the plasma characteristics that contribute to the fragmentation of the monomer in the plasma.

TaN thin-film coatings are well known for their good mechanical properties, acceptable toughness, as well as good biocompatibility. However, the friction coefficient of these films is sometimes too high, or the hemocompatibility is poor. The purpose of this study is to reduce the friction coefficient and increase the hydrophobicity of TaN coatings by introducing carbon and fluorine into the coatings. This study has never been conducted by other researchers. Fluorine-containing tantalum carbonitride (i.e., F–TaC_xN_y) top layers were deposited on TaN/Ta interlayers by reactive sputtering with fixed nitrogen and various hexafluoroethane (C₂F₆) mass flow rates. During the deposition process, C₂F₆ gas with various mass flow rates was added. After deposition, these F–TaC_xN_y multi-layered films were then characterized using XRD, XPS, FTIR, FESEM, WDS, a nano-indenter, a water contact-angle measurement system, and a tribometer. The tribological tests were carried out in the environment with and without humidity. The surface energies of the films were examined with water contact-angle variation. According to structural analysis, TaN phase would transform to TaC_xN_y with the increase in the C₂F₆ mass flow rate, which would result in a decrease in the friction coefficient and an increase in hydrophobicity. The films’ hardness (H, increased at most by 20%), elastic modulus (E), and H/E ratio first increased then decreased, most likely due to the increase in relatively soft C–F bonding. According to the results obtained from tribotesting, it was found that an increase in carbon and fluorine contents in the films reduces the friction by more than 30%, and wear rate by more than 50%. More importantly, the effects of moisture on the friction coefficient can be minimized to almost nothing. In a water contact-angle study, the contact angle increased from 60° to 85° with the increase in C₂F₆ mass flow rates. This evidence illustrated that hemocompatibility of the TaN thin film can be significantly enhanced through the formation of Ta–C and C–F_x bonding. The chemical composition and bonding status of these films, especially the existence of C–F_x bonds, were studied by FTIR and XPS. In sum, with the increased C₂F₆ mass flow rate, the carbon and fluorine contents in the films increased, while the nitrogen content decreased. The structure, bonding status, and compositions varied accordingly. The tribological behaviors were significantly improved. Furthermore, by carrying out tribotesting in humid air and a dry argon environment, it was confirmed that the greater the fluorine content, the less sensitive the films would be to environment change. This is attributable to the induced lower surface energy and reduced adsorption to water vapor due to the increase in C–F_x bonds. The successfully fabricated and studied F–TaC_xN_y films could be applied in many areas such as artificial blood vessels, or precision components in an atmospheric or vacuum environment.

The focus of this study is aimed at generating hollow cathode discharge (HCD) plasma inside three types of polymer tubes, resulting in the activation of tube's inner surfaces. To achieve this goal, both theoretical calculation and experiments were carried out to prove the adopted methodology was feasible. By applying optical emission spectroscopy, with line ratio and modified Boltzmann's plot methods, the plasma sheath could be estimated and applied to the prediction of HCD generation. To verify whether HCD prevails in the tube, the various power input (70 ~ 260 W), tube diameter (3 ~ 7 mm), and working pressure (0.1 and 0.4 torr) were selected. Accordingly, it was confirmed that the tube diameter must be greater than twice the plasma sheath, in order to form HCD, which would then activate the surface. Ar gas was used with a capacitive-coupled RF plasma system. PET, PU, and PTFE tubes were used in this study. The tubes’ inner surfaces were characterized with XPS, and water-contact-angle (WCA) analysis. The results also show that once HCD is generated inside the tubes, these tubes’ inner surface could become hydrophilic, and the values of WCA might decrease by 40°, 45° and 70° respectively for PET, PU, and PTFE, due to the combine effects of the enhanced ion bombardment and radical oxidation. XPS studies show that, for PET and PU, C-O and, particularly, C=O bonds increase significantly. For PTFE, the C-F bonds decrease, while carbonoxygen bonds increase. Overall, the surface activation is thought to be enhanced by ion bombardment attributable eventually to hollow cathode effect (HCE).