Biomedical Engineering Reference
In-Depth Information
Table 6.2
Liquid Contact Angles
γ
LV
(dyne/cm)
(dyne/cm)
d
LV
(dyne/cm)
p
LV
Liquid
Water
72.8
21.81
50.98
Fibrinogen
65.0
24.70
40.30
Albumin
65.0
31.38
33.62
Glycerol
63.4
37.21
26.21
Formamide
58.2
39.44
18.66
Diiodomethane
50.46
50.46
0
Human blood plasma
50.5
11.00
39.50
Ethylene glycol
48.3
29.27
19.01
Human blood
47.5
11.2
36.30
Tetrabromoethane
47.5
42.12
5.38
α
-Bromonaphthalene
44.6
31.70
12.89
4-Octanol
27.5
7.4
20.1
Most of the values were obtained at 20
°
C and from [7] and others from [8].
6.4.2.1 Determine the Components of Surface Energy
The intermolecular attraction that is responsible for surface energy,
, results from a
variety of intermolecular forces whose contribution to the total surface energy is ad-
ditive. The majority of these forces are functions of the particular chemical nature
of a certain material. A common approach to treating solid surface energies is that
of expressing any surface tension (usually against air) as a sum of:
γ
Polar or nondispersive component,
γ
p
(hydrogen bonding);
Dispersive component,
d
(e.g., van der Waals forces present in all systems
regardless of their chemical nature).
γ
Hence, the surface energy of any system can be described by
γγ γ
=+
d
p
(6.5)
In order to prove functionalization, one has to find dispersion (
γ
d
) and polar
p
) of surface energy. The interfacial tension between the liquid and
solid phases is then expressed in terms of the two components for each phase as
follows:
components (
γ
(
)
(
)
⎡
1/2
1/2
⎤
γ
=+−
γ
γ
2
γ
dd
γ
+
γ
pp
γ
⎢
⎥
SL
SV
LV
⎣
SV
LV
SV
LV
⎦
Substituting into (6.1),
(
)
(
)
(
)
⎡
1/2
1/2
⎤
W
=+− +−
γ
γ
γ
γ
2
γ
dd
γ
+
γ
pp
γ
⎢
⎥
A
SV
LV
SV
LV
⎣
SV
LV
SV
LV
⎦
