I spent summer time on developing two parallel paths of my research. I’ve continued studies concerning characteristics of multilayer polyelectrolyte films treated with various concentration of a genipin cross-linking agent. Moreover, I’ve also been working on thermal stability issues. Why? The answer is simple. The surface functionalization of materials intended for contact with blood by polyelectrolyte coatings will be successful, only if we have got the appropriate methodology for their manufacture on a large scale. Furthermore, polyelectrolyte coatings should have a tolerance to allow cryogenic storage and subsequent long-term application at physiological temperature, without any undesirable changes in the structure. Determination of the effect of temperature on the physico-chemical properties of coatings and potential to colonization by endothelial cells should be always a first step in studies on polymer for cardiovascular implant surface modification. Therefore, the aim of this study was to investigate changes in structure and properties of 12 bilayer porous coatings made of poly-L-lysine (PLL) and hyaluronic acid (HA) and subjected to temperature ranging from -50°C to +50°C. Herein, I determined how the post treatment chemical cross-linking of the coating may improve its thermal stability.
This month I carried out comparative analyzes of adhesive properties of silicon discs coated with thin inorganic films (DLC, TiOx, TiCN) in radial flow chamber, using concentrates of human blood erythrocytes.

I would like to look closer the influence of film thickness and annealing temperature on the obtained microstructure (particles geometry) and optical properties.

For that purpose I prepared poliched silicon wafers and microscope base glass. Those substrates were cut and cleaned with isopropanol and acetone. Next silicon wafers were passivated. Passivation is process of thermal surface oxidation realized in 850 Celsius degrees in oxygen atmosphere. After 15 minutes about 20nm thick layer of silicon dioxide occur at the surface and act as seperation layer between metal nanoparticles and semiconductor surface.

Subsequently on those substrate silver film of thickness 11,14,17 and 20 nm was sputtered. Samples with each thickness was annealed at the 200, 300 and 400 Celsius degrees for 1 hour.

For internal stress determinstion I try to apply XRD methods.

Obtained samples will be examined with SEM and AFM for microstructure description. Optical properties investigation will include diffused and specular reflectance and transmission measurements

Recently some of thin foils from KoBo extruded samples (comercial purity titanium and high purity zinc) have finally been examined in TEM and some crystal orientation microscopy have been performed on them. What was interesting is that although on SEM with EBSD, measured grain sizes are generally in micron range in TEM all types of deformed samples seems to have some nanostructures in them. This is especially visible in case of zinc where we could see 100 nm diameter grains in TEM while on EBSD average grain size was in range of 20 micrometers. Observed nanostructures can be responsible for characteristic fluctuation of misorientations inside zinc grains.
Second interesting observation is that although diffraction patterns from zinc seem to be of good quality, indexing program is unable to properly solve diffraction for zinc lattice. Our colleagues from AGH already had similar problems but in case of SAD patterns. It seems as though zinc after KoBo had different lattice parameters than the same material before the deformation.

Main studies carried out during this month:

- TEM investigations on the samples with Ti, Zr and Hf addition after annealing

- participation in the conference The 20th International Symposium on Metastable, Amorphous and Nanostructured Materials (ISMANAM 2013). During poster session I presented work with the title: „“Effect of Ti, Zr and Hf addition on microstructure and properties of rapidly solidified Al-Mn-Fe alloy”.

In July I’ve worked on my next publication, entitled :” Tin-zinc alloy electrodeposition from citrate baths”. In this paper I described in details the results obtained during the firsth and the second year of my studies, when I was studying ternary system Sn(II)-Zn(II)-Mo(VI). Currently I resigned from putting this part concerning Sn deposition in my doctoral thesis, because the system Zn(II)-Mo(VI) is the most interesting and difficult enough to write a doctoral dissertation about it. But, in my opinion the results concerning the tin-zinc alloy deposition are worth to be published.