Biomedical Engineering Reference
In-Depth Information
block-copolymers, blends of two AB diblocks [58], and AB diblocks
blended with homopolymers [67, 52] or small plasticizing molecules
[89]. A comprehensive review can be found in Ref. [81].
The fascinating bicontinuous topology of the gyroid phase
makes it an irresistible target for replication in functional materials
for applications in nanotechnology. While a of number porous
gyroid materials obtained from sacrificial block copolymers have
been identified in bulk (Table 2.1), successful replication of gyroid
film templates has only been rather recently achieved [69, 90, 61].
The first electrochemical replication, in 2008, was actually achieved
using a EO
17
surfactant templated silica film [90]. Further
exploration and applications of replicated gyroid networks remains
a current topic of great interest.
-PO
12
-C
14
2.4.6.1 Viewing the porous gyroid morphology
The porous gyroid morphology refers to the structure left by
removal of the minority polymer network domains (the inverse is
often referred to as the relief gyroid morphology). Whether viewed
in bulk samples or thin films, the multitude of surface morphologies
presented by the porous gyroid, visible under high resolution electron
microscopy, can be rather confusing. A better understanding can be
obtained by comparison to a simulation of the constant thickness
gyroid morphology. In practice a trigonometric level set function is
used as an approximation of the gyroid minimal surface [65, 91]:
2
πx
L
2
πy
L
2
πy
L
2
πz
L
f
(
x
,
y
,
z
) = sin( )cos( )+ sin( )cos( )
2
πz
L
2
πx
L
+ sin( )cos(
)
= 0, (2.10)
where
is the cubic unit cell repeat distance. The surface defined
by Eq. 2.10 divides space into two equal volumes. Computer
simulation
L
3
of this surface is used to construct the two related level
3
With thanks to Dr Gilman Toombes, based on the work of Jim Hoffmanhttp://www.
msri.org/about/sgp/jim/geom/level/skeletal/index.html.
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