Biomedical Engineering Reference
In-Depth Information
Figure 6.6
A schematic drawing of the relation between self-organization
(directional deposition of HA on collagen) and interfacial
interaction in biocomposites. Direction of interaction between
HA and collagen is restricted by covalent bond between COO
and Ca(2) to maintain regular coordination number of 7.
Reprinted from Ref. [747] with permission.
FTIR spectroscopy seems to be the major tool to study a possible
chemical bonding among the phases in calcium orthophosphate-
based biocomposites and hybrid biomaterials [276, 310, 345,
353, 355, 462, 513, 600, 616, 629, 635, 638, 641, 644, 653, 664,
673, 678, 709, 753, 802, 803, 847, 882, 1133-1136]. For example,
the characteristic bands at 2918, 2850 and 1472 cm
−1
for the
hydrocarbon backbone of PE appeared to have zero shift in an
HA/PE biocomposite. However, in the case of polyamide, several
FTIR bands indicated that the polar groups shifted apparently: the
bands at 3304, 1273 and 692 cm
−1
derived from stretching of N-H,
stretching of C-N-H and vibrating of N-H moved to 3306, 1275
and 690 cm
, respectively, in the HA/polyamide biocomposites.
Furthermore, both stretching (3568 cm
−1
−1
−1
) and vibrating (692 cm
)
−1
in the HA/
polyamide biocomposites, respectively, indicating the formation
of hydrogen bonds. Besides, bands at 1094 and 1031 cm
modes of hydroxide in HA moved to 3570 and 690 cm
−1
of PO
4
in the HA/polyamide
biocomposite. The bands shift in a fingerprint area indicated that the
hydroxide and orthophosphate on the surface of HA might interact
with plentiful carboxyl and amino groups of polyamide through
nucleophilic addition [276]. Comparable conclusions were made
for HA/PVA [641], CDHA/alginate [709], ACP/PPF [513], HA/maleic
modes also shifted to 1093 and 1033 cm
−1
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