Evaluation of the Impact of Parylene C Deposition Method on the Functional Properties of Fabrics.

The article presents the results of research on the impact of the use of an original, innovative method of deposition of Parylene C on the functional properties of fabrics with various potential applications (e.g., thermal and chemical protective clothing, packaging, covers and others). Verification of the effects of the method used was based on interdisciplinary research taking into account the impact of coating fabrics on changes in their structure (micro-CT), surface properties (contact angle), barrier properties (water and chemical liquid wetting), electrostatic properties (charge decay), biophysical properties describing heat and mass transfer (by the Alambeta system and thermal imaging) and flammable properties. Four fabrics made of synthetic organic fibres (meta-aramid, para-aramid) and natural inorganic fibres (basalt) were selected for testing. Given the complex structure of textile substrates, the results confirmed that the two assumed thicknesses of the Parylene C coating were consistent with the actual measurements. The findings indicated that the coatings significantly reduced water and acid absorption in the fabrics compared to unmodified ones. Thermal insulation property tests revealed that coated fabrics exhibited higher thermal conductivity than unmodified fabrics. Additionally, the presence of Parylene C on aramid fabrics resulted in a modest increase in their ignition resistance.

Application of parylene for surface (polymer) enhanced laser desorption/ionization of synthetic polymers.

RATIONALE: Synthetic polymers of molecular masses up to a few kDa can be analyzed without the use of any matrix by direct laser desorption/ionization mass spectrometry (LDI-MS). In this technique, the surface of the sample plate plays a crucial role, and many attempts have been made to understand the influence of the surface on the ease of desorption. Since this technique requires no tedious sample pretreatment, it is a promising method for the rapid characterization of various synthetic polymers. METHODS: Parylene (poly(p-xylylenes), PPX) was tested as a surface support for studying the molecular masses of biocompatible polymers: poly(ethylene glycol) (PEG), poly(L-lactide) (PLLA), and poly(methyl methacrylate) (PMMA). The average molecular masses of the polymers were: PEG (600.0 Da and 3.5 kDa), PMMA (2.0 kDa), and PLLA (2.8 kDa). RESULTS: LDI mass spectra of polymers deposited on parylene were enhanced by a factor of two over those obtained directly from the gold target plate. CONCLUSIONS: Modification of the surface of the target plate by the addition of a PPX layer extended the functionality of LDI-TOF MS, especially for the analysis of low-mass compounds. The LDI analysis using the PPX-coated target plate provided details of polymers including: end-group, composition, monomer unit, and molecular mass distribution. The average molecular weights of four tested polymers on the gold target plate and the PPX support were unchanged, indicating that sample degradation was not occurring despite the high energy of the laser beam. The LDI investigations showed that the PPX support boosted ion yields by a factor of two compared with the gold target plate.

High-performance single crystal organic field-effect transistors based on two dithiophene-tetrathiafulvalene (DT-TTF) polymorphs.

Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on two different polymorphs of dithiophene-tetrathiafulvalene, which were investigated by confocal Raman spectroscopy and X-ray diffraction, are reported. OFET devices prepared using different configurations show that both polymorphs exhibited excellent device performance, although the -phase revealed charge carrier mobility between two and ten times higher in accordance to the closer stacking of the molecules.

Interaction of parylene C with biological objects.

The aim of the present work was to examine the interactions of parylene C with such selected biological objects as: blood plasma proteins, platelets, endothelial cells, and bacterial biofilm produced by E. coli cells. The results obtained strongly support the thesis that parylene C is a material worth considering for biomedical use. Parylene C coating on polished medical steel significantly reduces platelet adhesion to this surface. On the other hand, in the case of the surface of machined medical steel coated with parylene C, the number of adhered platelets is significantly higher. This also means that surface texture of substrate material is very well reproduced by parylene C coating and is an important factor facilitating the platelet adhesion. Adsorption of plasma proteins at parylene C surface is very effective, and this finding confirms a notion that cell interaction with surfaces is mediated by the adsorbed proteins. In the light of the above, a high susceptibility of parylene C surface to bacterial colonization is easy to explain. The results showing reduced proliferation and changes in endothelial cell gene expression should also be seriously analysed when parylene C is considered for the use in contact with blood vessels.