Biomedical Engineering Reference
In-Depth Information
(a)
(b)
60
50
40
6
30
5
4
20
3
10
4
7
L
0
10
20
30
40
50
60
70
l
X
2
d
1
100Å
D
2.21
(a) 2D SANS pattern shown as isointensity contours from nylon
6 fi bers infused with D
2
O. (b) Fibrillar model to explain the 2D SANS
patterns in terms of partitioning of water into interfi brillar (nos. 3 and 6)
and interlamellar (nos. 4 and 5) regions.
60
solvents into the polymer matrix, contrast is generated by the distribution
of the deuterated solvents into the non-deuterated polymer. An example
of this is the study of hydration in polymers. Figure 2.21 shows the SANS
pattern from a nylon 6 fi ber exposed to D
2
O.
47
The contrast arises from the
preferential diffusion of D2O into the amorphous regions of the polymers.
There are two features in the SANS pattern. The lamellar peaks on either
side of the fi ber axis in the pattern are attributed to the distribution of D
2
O
in the interlamellar regions of the fi ber. The diffuse equatorial streak near
the center is attributed to D
2
O that is present along the fi ber-axis in the
spaces between the fi brils. This is illustrated in the schematic model of the
fi ber that shows typical lamellar structure of a semicrystalline polymer in
which the stacks of folded lamellae form fi brils that are oriented along the
fi ber- or the draw-axis.
60
2.8 Acknowledgment
This work was supported by RESBIO (Integrated Technology Resource
for Polymeric Biomaterials) funded by National Institute of Health (NIBIB
and NCMHD) under grant P41 EB001046. The content is solely the respon-
sibility of the author and does not necessarily represent the offi cial views of
the NIH, NIBIB or NCMHD.
