Biomedical Engineering Reference
In-Depth Information
5500
5000
4500
4000
3500
3000
4
6
8
10
12
14
16
Mol% n-decanol
Figure 4.16
Effect of
n
-decanol on the molecular weight of a poly(ortho ester) prepared from
3,9 - diethylidene - 2,4,8,10 - tetraoxaspiro [5.5] undecane, 1,10 - decanediol and 1,10 - decanediol
lactide (100/70/30).
1800
1600
1400
1200
1000
800
600
400
200
0
Polymer batch
Figure 4.17
Variation in Brookfi eld viscosity
for nine typical preparations at 25 °C.
Injectable formulation prepared from
3,9 - diethylidene - 2,4,8,10 - tetraoxaspiro[5.5]
undecane, TEG, and TEG-GL (60/50/50).
Formulation contains 20 wt% monomethoxy
polyethylene glycol, molecular weight 550.
Reprinted from [31], p. 4399, with permission
from Elsevier.
Because the principal means of administration of gel-like materials is by injec-
tion, preparation of materials having reproducible viscosities is important. Syn-
thesis reproducibility as measured by Brookfi eld viscosity for a number of different
preparations is shown in Figure 4.17 [31]. Clearly, the synthesis is suffi ciently
reproducible to assure that the same viscosity materials can be repeatedly
prepared.
