Polisiloxane layers modified by carbone nanotubes on metallic substrates


                

Project manager:

Realised by:

Grant no.:

  • 2017/25/B/ST8/02602

Start date:

  • 2018-03-05

End date:

  • 2021-03-04

1.      Objective of the study/research hypothesis

The subject of the study will be layers made of nanotubes coated by organosilicon polymer and the same material but after heat treatment - ceramization. Coating of nanotubes by organosilicon polymers and thermally treating them causes the obtainment of materials of desired specific topography for many applications, resistant to oxidative environment, of high mechanical parameters and good electrical conductivity. We expect therefore that the planed examination will lead to the obtainment of two kinds of layers (polymeric and ceramic) modified by the presence of carbon nanotubes acquiring them new desired properties. We will also indicate which parameters of carbon nanotubes and which features of the polymer have a decisive influence on the structure, phase composition, topography and other physicochemical and biological parameters of the layers.

To achieve it, the obtainment of a possibly complete description of the phenomena occurring on the interface matrix/carbon nanotubes dependent on the  parameters of nanoparticle and polymer was chosen as the main objective. We would like to prove that it is possible to obtain materials of differentiated physicochemical as well as biological parameters, including one useful for medical application, by the modification of nanotubes and precise control of the process of coatings preparation. As the final effect, it will allow conscious design of nanocomposite with properties founded in advance.

2.      Applied research methods/methodology

In the project it is planned to obtain several dozens of kinds of layers based on polysiloxanes modified by carbon nanotubes of a different shape, length of functionalization on asthenic steel and titanium. All of the layers will be deposited on the metallic surfaces by EDP and/or dip-coating method. They are composite materials. Therefore, sequential deposition and/or codeposition processes are essential to use. In the case of the obtainment of black glasses, performed layers will undergo the ceramization process in the protective atmosphere (pyrolysis). Conditions of ceramization (temperature, time, heating rate) will be selected basing on thermal analysis (DTA, DSC, DTG). Structure of all of the obtained layers will be analyzed in detail (Raman, FTIR, XPS) as well as their microstructure (SEM, TEM, AFM, confocal microscope). Characterization of the structure of the composite materials is an extremely difficult task due to the need of describing the structure of the matrix, dispersed phase of the nanometric size as well as the interface between them and between the layer and the substrate. Vibrational spectroscopy (FTIR, Raman) will allow designation with big precision of types of bonds occurring in the projected composite layers. The application of Raman microscopy and FTIR gives a chance to separate defining of the structure of the matrix and nanotubes. Microscopic examination microstructure (confocal microscope, SEM, TEM, AFM) will allow the determination of the thickness of the layer and of the state of the surface. One of the principal parameters of designed coatings is their wettability, which will be controlled basing on analysis of the shape of the droplet using goniometer equipped with a temperature chamber. In order to precise determination of mechanical parameters of the nanocomposite layers, the nanomechanical tests will be performed basing on the nanoindentation method. These examination will allow the obtainment of maps of the distribution of mechanical parameters and maps of stress distribution for the nanocomposites. All of the obtained layers must be characterized by good tightness and corrosion resistibility. Therefore, suitable corrosion tests in so-called Ringer solution will be performed. It is necessary to define bioactivity of the layers. It will be done by incubation of the materials in stimulated body fluid and control of the growth of a phosphate phase. Materials will be also evaluated for their biological properties.

All of the planned structural, microstructural, physicochemical parameter tests of the obtained materials will allow determination of principal operational parameters of the designed functional layers. Correlation between maps of conductivity distribution, mechanical properties and stress with obtained Raman maps seem to be particularly interesting.

3.      Influence of the expected results on the development of science, civilization and society

With the development of medicine the need for the materials useful for therapy and diagnostics. Despite the great progress in the field of materials for osteosynthesis in orthopedy or stomatology, the work on new solutions for the modifications of the implant surfaces, especially the ones based on steel or titanium, is continued. Our research project will lead to the formation of elementary knowledge, which will facilitate the conscious supervision of the process of the obtainment of nanocomposite coatings. It will indicate the correlation between the phenomena occurring on the interface of two phases constituting  the layer on the molecular level and its properties (such as surface topography, surface free energy, electrical conductivity, adhesion to the substrate) and, finally, the parameters important from the point of view of further applications. At the same time, the usage of polysiloxane or black glasses properties and carbon nanotubes will provide proposing a new class of materials for medical applications. From the point of view of the previously outlined reasons, the scientific description of novel materials for medical applications will have a great value for the quality of human life.