Chemistry Reference
In-Depth Information
ABSTRACT
The specific features of novel blends on the basis of copolymers 3-hy-
droxybutyrate with hydroxyl valerate (95:5 mol %) (PHBV) and seg-
mented polyetherurethane (SPEU) have been investigated. The samples
with different content (100/0, 60/40, 40/60, 50/50, and 0/100 wt.%) are ex-
plored by structural (WAXS, FTIR), thermo physical (DSC) and dynam-
ic (probe ESR nano analysis, H-D isotopic exchange) methods at about
physiological (40 °C) and elevated (70 °C) temperatures after treatment by
water or heavy water. It was shown that for the first 5 h during water ex-
position at 40 °C the individual polymers (PHB and SPEU) and the blends
kept structural stability that was confirmed by ESR time correlation data
for the probe TEMPO and stable crystallinity (WAXS, DSC). Dependence
of H-D exchange rate on the blend content has minimum at PHB/SPEU
ratio 60/40. At 70 °C the water-temperature effect leads to enhanced mo-
lecular mobility of TEMPO in all systems besides the individual PHB. In
accordance with DSC data in this case the crystallinity and melting points
of PHBV are decreased. The descriptions of PHBV-SPEU system using
a combination of structural and dynamic features gives a more complete
assessment of its structural evolution at relatively short-term times, which
precede its hydrolytic decomposition.
2.1 INTRODUCTION
The new biodegradable blends based on the combination of synthetic and
natural polymers are alternative option for the use of individual polymers.
As a result of composite production it is expected the emergence of es-
sentially new exploitation characteristics, which are not inherent to the
original polymer components. Biodegradable systems are widely used in
innovative technologies for the drug delivery, in tissue engineering, and
prosthetic vascular stenting, in a contemporary design of environmentally
friendly barrier materials in packaging [1-3]. When creating such sys-
tems, segmented polyetherurethanes (conventional SPEU on the basis of
multifunctional isocyanates) may be of particular interest. Because of the
unique combination between mechanical properties and biocompatibility,
they are widely and successfully applied in various fields of biomedicine
as constructional and functional materials [4, 5]. However, the low rate
of SPEU biodegradation, which is a positive factor in the case of a long-
