Environmental Engineering Reference
In-Depth Information
was 2 and 5µm which were similar to the values observed for a pure PEGlyated
background. At dimensions less than 20µm, the
Ulva
spores were no longer able to
differentiate between PEGylated and luorinated features and they regarded them as
a pure PEG surface and no longer settled on them [86].
A hyperbranched amphiphilic polymer coating was designed based on the principle
that non-uniform surface characteristics would negatively affect the ability of a
protein molecule to adsorb and unfold on the surface. Gudipati and co-workers [87]
synthesised surfaces comprising of hyperbranched luoropolymers (HBFP) and PEG
chains (
Figure 2.23
). This network exhibited surface reconstruction when placed
in water, which resulted in surface segregation leading to a more hydrophilic PEG
component at the coating/liquid interface. They proposed that a polymer after-coating
which has smaller sized surface heterogeneities would improve resistance to protein
adsorption and cell adhesion. Amphiphilic networks with 14% (HBFP−PEG14),
29% (HBFP−PEG29), 45% (HBFP−PEG45), and 55% (HBFP−PEG55) PEG were
prepared on(3-aminopropyl)triethoxysilane (APTES) functionalised microscope glass
slides and tested. The surface free energy increased with increase in the concentration
of PEG, namely from 22.27 mJ/m
2
for pure HBFP coating to 34.96 mJ/m
2
for a
HBFP-PEG coating containing 55% PEG. Among all the network coatings, HBFP-
PEG45 recorded the maximum resistance to adhesion of protein, lipopolysaccharide,
and
Ulva
zoospores, as well as exhibiting the best zoospore and sporeling release
properties. This polymer network also displayed better release properties than a
standard PDMS coating.
To overcome the problems associated with poor mechanical properties of PDMS
coatings, silicone PU-block copolymers were investigated for their use as anti-fouling
coatings using combinatorial high-throughput methods [88].
Ekin and co-workers [89] synthesised a crosslinked siloxane-PU coating. They used
a high throughput synthesis method to synthesise 72 novel hydroxyalkyl carbamate
and dihydroxyalkyl carbamate-terminated PDMS oligomers and their carbamate-
linked block copolymers with poly(e-caprolactone). These oligomers were then
incorporated into siloxane-PU formulations at four different levels resulting in 288
coatings. Hydroxyalkyl carbamate terminated PDMS coatings showed a lower
adhesion of barnacles than the dihydroxyalkyl carbamate-terminated PDMS.
The barnacles showed opposite behaviour in the adhesion assay.
