Chemistry Reference
In-Depth Information
6.7.3 Self-Healing
For some applications, it is necessary to maintain a hydrophobic surface.
If the surface is damaged then the recovery or restructuring is beneficial
and is called self-healing. In this sense, PDMS is a “smart material,” in
that it responds constructively to a change in the environment.
Self-healing is often used in a broader sense, to mean reconstruction of
the entire polymer instead of just its surface.
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A relevant example here is
a PDMS elastomer that contains microencapsulated PDMS resin and mi-
croencapsulated cross linker.
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If this type of PDMS is damaged, both cap-
sules rupture and the newly formed elastomer mends the damaged area.
6.8 INTERACTIONS WITH BIOMOLECULES
6.8.1 Trapped Biomolecules
Biologically active molecules are sometimes trapped in PDMS when end-
functionalized PDMS chains are linked into a network structure. This
method has been done, for example, with a lipase enzyme.
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he PDMS
plays a beneficial role as an activator or protective agent. Similar results
were found for the enzyme α-chymotripsin, with some short-chain
poly(ethylene oxide) used to enhance enzymatic activity.
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It is also pos-
sible to generate microtopographic patterns that affect
Escherichia coli
bio-
film formation on PDMS surfaces.
6.8.2 Controlled Release
Surface graft polymerization of poly(ethylene glycol) acrylate was used to
modify the surface of PDMS.
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Templates with channels were formed
from this material and sol-gel chemistry was used to form amino-silane
doped xerogel microarrays. These structures were then used to release
nitric oxide at various rates, by control of micropattern dimensions, type
and concentration of the amino-silane, and so on. This method parallels
the use of polymers in controlled drug-delivery systems.
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6.8.3 Protein Adsorption
Proteins react with silicon-containing materials in a variety of ways.
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For example, peptides in a phage library were exposed to the surface of
