Biomedical Engineering Reference
In-Depth Information
1.00
0.90
C-H stretching
C=O ester stretch
0.80
0.70
d
0.60
0.50
c
0.40
0.30
b
0.20
0.10
a
0.00
3900
3400
2900
2400
1900
1400
900
400
Wavenumbers (cm 1 )
Figure8.15 StackedFTIRspectraofchitinandchitinesters.(a)chitinnanocrystals,(b)chitin
hexanoate,(c)chitinnonanoate,(d)chitinstearate.
Table8.2 Contactanglemeasurementsforthechitinnanoparticles.
Sample
Contact angle (deg)
Polar
Dispersive
Surface energy
(dyne/cm)
(dyne/cm)
(dyne/cm)
Water
Methylene iodide
Chitin NC
27
41
41
25
66
Chitin C6
95
30
1
45
46
Chitin C9
121
38
4
48
53
Chitin C18
119
41
3
46
49
to existing as free unattached acids perhaps stabilized by hydrogen bonds to the chitin
molecule.
Also, after modification, we observe increasing signal intensities in the region between
2930 and 2860 cm 1 , corresponding to asymmetric and symmetric stretches of the methy-
lene groups, respectively. Chitin has broad bands in this region with signals arising
from C-H stretching in the pyranose ring. After esterification, the signals in this region
sharpen and increase in intensity as longer aliphatic esters are attached and the population
of methylene groups increases.
The results from static contact angle experiments using the sessile drop method are
provided in Table 8.2. They demonstrate the increase in hydrophobic character at the
particle surface as a consequence of derivatization. Other analyses were performed, but
are not shown, which further confirm the chemical derivatization of the surface of chitin
nanoparticles.
Search WWH ::




Custom Search