Biomedical Engineering Reference
In-Depth Information
Fig. 13
ε
s
-
Π
for polymeric monolayers at
A
/
W
. The symbols correspond to data for
PtBMA (
). The initial slopes in
both are drawn in for the good solvent limit (
solid line
)andthethetalimit(
dashed line
)
), PMMA (
), PVAc (
◦
), PMA (
), PEO (
♦
), PTHF (
sults for six polymers are displayed. The initial linear region stands for the
semi-dilute regime. As referred to above, the maximum
s
in each case is ob-
served well beyond the point when the isotherms depart from the semi-dilute
regime. The initial slopes in the plots provide the scaling exponent y, and
clearly a division into two groups emerges. The good solvent condition rep-
resented by solid lines applies to PVAc, PMA, PEO and PTHF with y
ε
3 (2.86
to be exact), whereas a poor solvent condition (not quite theta condition in-
dicated by dashed lines) with y
≈
18, applies to PMMA and PtBMA. Clearly,
methacrylate polymers with a polypropylene backbone form different mono-
layers than those with the polyethylene backbone or polyether. We truncate
further presentation of the static results and proceed directly to the dynamics
by SLS.
We present the viscoelastic characterization of these polymers as deduced
from SLS. By means of the scheme outlined with Fig. 4, we demonstrate in
Fig. 14 that two groups of polymers are well differentiated in terms of their
“polar profile”, that is their progression of
≈
ε
d
and
κ
with increasing
Π
.In
the figure, those under the good solvent condition with y
3, PVAc, PMA,
PEO and PTHF, are shown in (A) and those under the poor solvent condi-
≈
