62 - Polskie Stowarzyszenie Biomateriałów

4
SCHEME 2. Chemical structure of poly(ester-ether-ester) terpolymer.
In our work we focused on polyester–type condensation
copolymers with poly(butylene terephthalate) as hard
segment and two components of soft segments: dilinoleic
acid (dimer) and poly(ethylene glycol) (SCHEME 2).
The nanoreinforcement concept was realized through adding
hydroxyapatite nanoparticles (FIG. 1) to produce highly
elastomeric and strong materials.
FIG. 1. TEM picture of nanosized hydroxyapa-
The chemical structure of the neat PBT/DLA/PEG 1000
terpolymer containing 45 wt% hard segments (PBT),
19 wt% soft segments DLA, and 36 wt% soft segments PEG 1000
and its nanocomposites was studied using Fourier transform
attenuated total reflection infrared spectroscopy (ATR-FTIR).
IR spectra for the neat PBT/DLA/PEG 1000 terpolymer (FIG.
2) revealed the presence of characteristic peaks confi rming
expected chemical structure of polymers. Peak at
1712 cm -1 was assigned to ν(C=O) stretching, characteristic
of dimer acids. The bands at 2929 and 2856 cm -1 correspond
to ν(C-H) stretching, and its high intensity reflected
high amount of the aliphatic ester segments. A peak at
3500 cm -1 was attributed to the ν(O-H) end groups stretching.
The bands at 1150 cm -1 corresponded to ν(C-O-C)
stretching. This refl ects presence of ether segments of
PEG 1000 . ATR-FTIR spectra of hybrid materials did not reveal
any changes (therefore they are not presented in a paper)
as compared to the neat terpolymer indicating the lack
of changes of polymer chemical structure upon addition
of ceramic powder into polymer matrix.
Fracture surface of materials containing HAP and
without HAP were observed with SEM. PBT/DLA/PEG 1000
terpolymer at concentration of 45 wt% hard segments is an
FIG. 2. ATR-FTIR spectra of PBT/DLA/PEG 1000
terpolymers with and without VE.
elastomeric material and SEM pictures showed fl at fracture
surface for neat terpolymers (FIGS. 3a,b). PBT/DLA/PEG 1000
synthesized in presence of VE showed more elastic fi brils
after fracture during tensile testing (FIG. 3b) as compared
to polymer without thermal stabilizer (more fl at and brittle
fracture surface, FIG. 3a). Formation of organic/inorganic
composites during in situ polycondensation reaction in presence
of HAP of grains size of 300–500 nm resulted in good
dispersion of ceramic particles within polymer matrix (FIGS.
3c–f). Thin fi brils binding ceramic particles with polymer
matrix were observed at fracture surfaces (FIGS. 3c,d) for
PBT/DLA/PEG 1000 sample containing HAP I (non-calcined),
without VE. Addition of VE to the system appeared in formation
of agglomerates (~1 μm). An opposite behaviour was
observed for PBT/DLA/PEG 1000 sample containing HAP III
(sintered), where more fi brils binding ceramic particles with
polymer matrix were observed for system containing thermal
stabilizer (FIG. 3f).