Deposition, morphology and functional properties of layers based on DLC:Si and DLC:N on polyurethane

Abstract

DLC:Si and DLC:N (diamond-like carbons doped with Si or N) functional layers in different configurations are deposited on polyurethane (PU) for bioengineering applications using CCP (capacitively coupled plasma) discharge generated in the PE CVD (plasma-enhanced chemical vapor deposition) system. Scanning electron microscopy (SEM) observations show that the obtained single and multilayers are continuous and well adherent to the substrates, but they differ in surface morphologies. DLC:Si layers form granular-like outer surfaces, while DLC:N ones a mosaic structure of plain areas. Topography analyses by atomic force microscopy (AFM) and optical profilometry reveal that Si-doped layers are characterized by significantly higher surface roughness (Ra ca. 5 nm) in comparison to N-doped layers (Ra ca. 0.3 nm) and also higher values of profile roughness parameter Rz (up to 32 μm vs. about 13 μm). Energy-dispersive X-ray spectroscopy (EDS) analysis indicates the homogenous chemical composition of the layers. DLC:N layers, are characterized by significantly higher polar component of surface free energy (up to ca. 5.0 mJ/m2). DLC:Si layers exhibit higher values of diiodomethane contact angle (up to ca. 90°) compared with DLC:N layers (up to ca. 55°). The attenuated total reflectance Fourier transform infrared spectroscopic measurements (ATR-FTIR) of the layers reveal that the addition of silicon to the DLC structure increases the content of terminal CHn bonds (n = 1, 2, 3) as well as beneficial Si–H and Si–CHn bonds, which significantly reduce the internal stresses in the layers. Both DLC:Si and DLC:N layers exhibit no cytotoxic effects using the human osteoblast-like cell line and human keratinocytes.

Laser-patterned carbon coatings on flexible and optically transparent plastic substrates for advanced biomedical sensing and implant applications

“…Notably, the properties of DLC thin films are reported to be considerably different on polymeric substrates than on other substrates. 36 (a) Fabrication of pristine DLC coatings on F-RIE HDPE substrate by PLD. Researchers have previously tried to deposit DLC films on HDPE by vacuum pulsed sputtering.…”

“…Surfaces with significantly low wettability are promising candidates for several biomedical applications. [50][51][52] For instance, hydrophobic surfaces can show antithrombotic properties by facilitating the blood flow and reducing the shear stress between the solid and liquid interface. 36,37 They can also exhibit antimicrobial, self-cleaning, and anti-biofouling properties since the low adhesive forces and rough topographies reduce the contact area between an implant and its surroundings.…”

“…[50][51][52] For instance, hydrophobic surfaces can show antithrombotic properties by facilitating the blood flow and reducing the shear stress between the solid and liquid interface. 36,37 They can also exhibit antimicrobial, self-cleaning, and anti-biofouling properties since the low adhesive forces and rough topographies reduce the contact area between an implant and its surroundings. 53 For example, DLC-modified HDPE is utilized in coronary stents due to its antithrombotic properties.…”

Characterization and Properties of Diamond-Like Carbon Coatings

“…DLC coatings have aroused great scientific and industrial interest since the beginning of the 70s due to their very good mechanical, physical [1], tribological and anti-corrosion properties [2]. The coatings have a very smooth surface [3][4][5], high hardness [1,[3][4][5][6], low friction coefficient, high wear resistance [1,3,4,7,8], good thermal conductivity, high transparency [1,5], good chemical inertness [1,[4][5][6] and biocompatibility [1,4,7,9]. In addition, the coatings can be applied for protective purposes, e.g.…”

“…The physical and mechanical properties of the resulting (modified) surface depend on the type of substrate, method of deposition, layer thickness, applied precursors, etc. [4].…”