Barbieri Thesis - BioMedical Materials program (BMM)

Chapter 7 – Polymer mole ecular weight annd
instructive co omposites
equivalencce,
while the patterns of th he two compoosites
displaye ed all the poly ymers and
apatite bannds
demonstrating
that the apatite particcles
were succ cessfully intro oduced into
the polymeers
(Figure 1bb).
After burning
the polymeers
out, only apatite was le eft and the
composition
of the two composites could c be determined
(Table 2), resulting close c to the
expected contents of 50%wt. In particular,
no significant differences
in the initial
apatite/polyymer
contentt
between ML M and MH were observ ved (p>0.73). Scanning
electron microscopy
(SEEM)
images of
loose granules
demonstra ated similar nano–rough
surface toppographies
for
both compo osites with expposed
acicula ar–shaped apa atite nano–
particles thhat
might be the main resp ponsible for thhe
rough topo ographies (Fig gure 2a,c).
Homogeneeous
cores, with no la arge apatite agglomerate es, were observed
in
backscatteered
scanningg
electron (B BSEM) imagees
of the cro oss–sectioned d granules
(Figures 2b,d).
Alkali treeatment
affec cted the compposites
surfac ce, resulting in
a partial
removal off
the polymer
and exposu ure of apatitee
particles (Figure
2b,d). In the two
materials, the exposed apatite layers s had similar average thick kness (p>0.28 8) and they
surroundedd
the granulees
covering similar perceentage
perime eters (p>0.8) (Table 3)
indicating tthat
alkali treaatment
had sim milar effect on the two materials.
Figure 1. (aa)
XRD and (b) FTIR spectra for f apatite, the ttwo
polymers (P PDL–H and PDL L–L) and the
composites tthereof
(MH and ML). Polymers have amorphouss
component as demonstrated by
their broad
XRD patternss.
From the commposite
XRD spe ectra it can be sseen
that apatite was introduced into the two
polymers. Thhese
results aree
confirmed by the FTIR specctra,
showing th hat vibrational bands b of the
composites innclude
those of aapatite
and of the e two polymers. (cc)
TEM image of f apatite particles s. PDL–H and
PDL–L indiccate
high and low
molecular weight w poly(D,L– –lactide) respect tively; MH and ML indicate
composites pprepared
with high
and low molecu ular weight polymmer
respectively. TEM scale bar is s 200 nm.
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