Chemistry Reference
In-Depth Information
Chapter 10
Polymeric Materials for Special Applications
10.1 Polymer Supports for Reagents, Catalysts, and Drug Release
Supports are materials that are used for immobilization of various reagents, catalysts, drugs for
release. Many of them are specially prepared macromolecules. Reagents and catalysts on support find
applications in organic syntheses, biochemical reactions, special separations, and analyses. They also
find uses in medicine for drug release, etc. An advantage of immobilized polymeric reagents in
chemical reactions is that they can be separated, often easily by filtration, from the products of these
reaction. Cross-linked polymeric reagents have an additional advantage in that several different
polymeric reagents can be used simultaneously without the functional groups being accessible to
each other for interaction. Reactions of some compounds in solution require high dilutions. Immobi-
lization, however, may permit the same reactions to be carried out at relatively high concentrations.
Immobilization can also be very useful in syntheses that consist of many steps, where the undesired
by-products from each step can simply be washed away. This avoids lengthy isolation and purifica-
tion procedures [
2
]. Also, by immobilizing on a polymer, the macromolecule may provide microen-
vironmental effects to the attached species for the reactions. These may include special electronic and
steric conditions that could be different from those existing in bulk or in solution.
The chemical uses of polymeric reagents were originally classified by Patchornik according to the
general type of reaction [
1
].
These are as follows:
1. Polymer-attached reagents are used in
special separations
to selectively bind one or a few species
out of complex mixtures:
filter
+
+
A
B
A
BCDE
CDE
recovery
+
B
B
A
A
The polymer-bound compound is separated from the mixture and then released.
2. The polymer with a
catalyst
attached. Such catalysts can be enzymes, inorganic compounds, or
organometallic compounds:
+
+
A
substrate
product
A
