Composite materials made of electrospun polymer nanofibers coated by plasma-chemical deposited
layers: Preparation and properties

KEDROŇOVÁ, Eva^ 1,2,3; PŘÍHODA, Jiří^ 1; ZAJÍČKOVÁ, Lenka^ 2,3; HEGEMANN, Dirk^ 4; MANAKHOV, Anton
^3,5; KLÍMA, Miloš^ 2,3; KUPKA, Vojtěch^ 6; MICHLÍČEK, Miroslav^ 2,3^

^1 Department of Chemistry, Faculty of Science, Masaryk University Brno, Czech Republic

^2 Department of Physical Electronics, Faculty of Science, Masaryk University Brno, Czech Republic

^3 Plasma Technologies, CEITEC MU, Brno, Czech Republic

^4 EMPA St. Gallen, Switzerland

^5 National University of Science and Technology MISIS, Moscow, Russia

^6 Advanced Polymers and Composites, CEITEC BUT, Brno, Czech Republic

                     Electrospinning is commonly used for preparation of nanofibers from numerous
polymers. For particular application of the nanofibrous meshes there is a necessity of additional
surface treatment, in order to obtain required functional properties of resulting composite
materials. For this process, plasma chemical deposition from gas phase can be advantageous. Plasma
enhanced chemical vapor deposition (PECVD) is a versatile technique used for surface modification
and is suitable also for highly porous and temperature-sensitive materials such as electrospun
nanofibers. Several combinations of electrospun nanofibers and plasma-chemical coatings were
tested. First of all, organosilicon plasma polymers were deposited on PVA and PA6 electrospun
nanofibers from HMDSO/Ar mixtures. The organosilicon layer is supposed to increase the
hydrophobicity of the resulting nanofibrous meshes. Low pressure RF discharges with capacitive
coupling and cold RF plasma multi-jet working at atmospheric pressure were used for the depositions
and the process conditions were varied in order to get samples with different structure and
wettability. The influence of deposition conditions on chemical composition of the resulting layers
was investigated by IR spectroscopy and the XPS. The values of the WCA were strongly dependent on
both, chemical composition of deposited layers and overall surface structure. Significant variation
in microstructure of obtained composites were revealed by AFM and SEM analysis of materials
prepared by different plasma sources. The other type of investigated composited was composed of
electrospun PCL/PEG nanofibers prepared by electrospinning of the solutions containing various
ratios of PCL:PEG polymers ranging from 5:95 to 75:25. The optimization of PCL/PEG ratio, polymer
concentration and electrospinning conditions (e.g. voltage, electrodes distance) leads the changes
in substrate morphology, homogeneity and fiber thickness. The PCL:PEG ratio also influenced the
degradability and the mechanical properties of nanofibers. In order to improve the wettability of
the nanofibers a thin amine layer by means of cyclopropylamine plasma polymerization in RF
capacitively coupled discharge was deposited. The properties of the coated nanofibrous meshes were
studied by XPS, IR spectroscopy and SEM. The presence of the amine groups enhanced the adhesion and
proliferation of the cells, thus favors the properties of nanofibers for biomedical application.
The obtained results prove the high potential and variability of composite materials prepared by
plasma-coated electrospun meshes.