Chemistry Reference
In-Depth Information
6.5.3 Ion Beams
Poly(hydroxymethylsiloxane) surfaces have been modified with 6 keV Ar
+
beams, and the results compared with those from oxygen plasma treat-
ment.
101
The ion beam approach was much more successful in promoting
proliferation of human dermal fibroblasts. This result was attributed to a
peculiar electronic structure and related electrical properties in the ion-
containing PDMS. Low-energy ion beams have also been used to form
silica on PDMS surfaces.
102
6.6 SOME ADDITIONAL CHEMICAL ASPECTS
6.6.1 Emulsions
PDMS oil/water emulsions have been stabilized by adsorbing hybrid silox-
ane polymers at the droplet surface.
103
Examples of such additives are
PDMS backbones with side chains consisting of trimethylene spacers
ending with amino groups, methylated amino groups, acid groups, or an
ethylene oxide decamer. Microemulsions have also been prepared directly
from silicone oil with an anionic/nonionic surfactant mixture.
104
6.6.2 Radical Polymerization
Radical polymerization was used on acrylamide adsorbed onto a PDMS
surface.
105
The hydrophilic surface thus generated had a twenty-fold im-
provement in resisting irreversible adsorption of lysozyme and was stable
against reorganization to a hydrophobic surface for at least a month.
6.6.3 Copolymers with Polyurethanes
Segmented polyurethanes with PDMS blocks were found to have good en-
vironmental responsiveness.
106
The hydrophobic-to-hydrophilic transfor-
mation can be managed by varying the composition of the segments of the
polymer. The associated switchable properties could be of interest in a
number of applications including the release of soils, combating fouling,
and selective adsorption-desorption of proteins. Surface microtopogra-
phy studies of a thermoset siloxane-urethane system have been re-
ported.
107,
108
