Chemistry Reference
In-Depth Information
CHAPTER 8
POLYMERIC CAPSULES: CATALYSIS
AND DRUG DELIVERY
BRIAN P. MASON, JEREMY L. STEINBACHER, and
D. TYLER MCQUADE
8.1. INTRODUCTION
Defining “inside” from “outside” is a fundamental trait of living organisms. The
creation of nonnatural structures that can define in from out with nonpermeable or
semipermeable barriers offers the potential of protecting the internal content from
destruction, contamination, and unwanted dispersal until the content is delivered to
a defined location. Small spherical structures that define in and out are well known
and come in forms ranging from microcapsules to vesicles to micelles. We refer to
these structures collectively as polymeric capsules.
Synthesis of polymeric capsules involves polymer self-assembly on many levels
and length scales. Approaches to their synthesis include cases where monomers are
polymerized around a liquid template, premade polymers are assembled around
liquid and solid templates, premade particles are assembled around templates,
and small molecules or polymers assemble spontaneously. Each method offers
unique challenges and advantages, and each allows the production of capsules
with different properties.
Complementing the many methods for capsule preparation, these materials have a
wonderful array of applications including cosmetic use, drug delivery, passive dis-
plays, and healing materials. Because the field of synthetic polymer capsules is
over 85 years old, we readily acknowledge that this chapter is in no way comprehen-
sive. We will limit our discussion here to the two most relevant applications: catalytic
capsules and drug delivery. Although existing capsules with these properties are well
respected, we see a resurgence in these areas driven by the recent contributions of
both new materials and ideas by synthetic chemists.
