ficial receptors. There are a variety of such
monomers which can carry basic (e.g.,
vinylpyridine) or acidic (e.g., methacrylic
acid) functional groups. They can be per-
manently charged (e.g., 3-acrylamido-
propyltrimethyl ammonium chloride) or
hydrophobic (e.g., styrene) or be capable
of participating in hydrogen bonding (e.g.,
acrylamide) for participation in charge, hy-
drophobic, and/or hydrogen bonding in-
teractions in binding sites. Addition of a
solvent can be used to induce a porous
structure in the polymer to facilitate access
of the target molecules to the binding sites.
Other materials, such as polyphenols and
polyurethanes and sol–gels are also find-
ing use as imprinting matrices. [ 3]
Because of the way the binding sites are
created, their distribution, accessibility and
binding properties are often heterogeneous.
This is not always disadvantageous, but it
can be difficult for artificial receptors/im-
printed polymers to adequately substitute
for the flexibility and specificity of natural
molecules. In spite of this, imprinted poly-
mers have been used successfully for sepa-
rations, as catalysts, and as sensing elements
[ 3-4], and as such provide successful exam-
ples of one type of re-chargeable polymeric
materials.
The next innovation is to design and
build re-chargeable coatings that deliver a
desired functionality that can be replenished, refreshed or redirected (“
re-pro-grammed”) as needed. A novel illustration
of this concept is a metal-based antifouling
coating that charges and recharges itself
using environmental resources. By harnessing the properties of peptides and proteins
to selectively bind and release metals, metals
that are naturally found in the environment
can be utilized as an antifouling biocide.
Metals as Biocides for
Antifouling Coatings
Fouling refers to the surface adhesion of
molecules or other materials to a surface
upon contact with water (e.g., sea water,
fresh water). Biofouling is prevalent form
of fouling produced by the adhesion of
biomolecules (e.g., proteins, glycopro-
teins) and/or organisms, as opposed to in-
organic materials, and can begin within
minutes upon contact with water to pro-
duce an initial biofilm. Microorganisms
such as bacteria, diatoms, algae, marine
fungus, protozoan, cyprid and/or rotifer
generally incorporate into the fouling
biofilm within 24 hrs, though macroor-
ganisms (e.g., barnacles, tunicates, mol-
lusks, bryozoans) may adhere to the
surface days or weeks later. Biofouling oc-
curs worldwide in various industries (e.g.,
offshore oil and gas industries, fishing,
power stations, paper and pulp industries)
and a variety of locations (e.g., ship hulls,
heat exchangers, water-cooling pipes, pro-
pellers, ballast water). A fouled surface is
typically rougher and/or has a higher fric-
tional resistance property. For example, a
fouled ship’s surface may reduce the speed
of a vessel in water, reduce a vessel’s ma-
neuverability, increase a vessel’s weight,
increase a vessel’s fuel consumption (e.g.,
up to 40%), increase a vessel’s mainte-
nance time and/or repair cost in dry dock,
reduce the use time of a vessel, enhance
corrosion, alter a surface’s electrical con-
ductivity, and/or discolor a surface.
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