Biomedical Engineering Reference
In-Depth Information
3
Ionic Polymer-Metal
Nanocomposites:
Manufacturing
Techniques
3.1
INTRODUCTION
This chapter presents a detailed description of various techniques and experimental
procedures in manufacturing ionic polymer-metal nanocomposites (IPMNCs) that,
if fully developed, can be used as effective biomimetic sensors, actuators, and
artificial muscles. The performance of those IPMNCs manufactured by different
manufacturing techniques is presented and described. In particular, a number of
issues, such as force optimization using the Taguchi design of experiment tech-
nique, effects of different cations on electromechanical performance of IPMNCs,
electrode and particle size and distribution control, surface electroding, manufac-
turing cost minimization approaches by physical loading techniques, scaling and
three-dimensional muscle production issues, and heterogeneous composites, are also
reviewed and compiled.
3.2
IPMNC BASE MATERIALS
3.2.1
I
G
N
ENERAL
As we previously discussed in chapter 2, the manufacturing of IPMNC artificial
muscles, soft actuators, and sensors starts with
(or “permeable” or
“conducting”) polymers (often called “ionomers”; Eisenberg and Yeager, 1982;
Eisenberg and King, 1977). Ion-exchange materials are designed and synthesized to
selectively pass ions of single or multiple charges—that is, cations or anions or both.
Hence, depending upon the types of materials, selective passages of desirable cations
or anions or both ions can be achieved; this means that ions are mobile within the
polymeric materials. Ion-exchange materials are typically manufactured from
organic polymers that contain covalently bonded fixed ionic groups (Eisenberg and
Bailey, 1986).
Most popular ion-exchange materials used in industry are based upon copolymer
of styrene and divinylbenzene, where the fixed ionic groups are formed after poly-
merization. An important parameter is the ratio of styrene to divinylbenzene, which
controls the cross-linking process that limits ion-exchange capabilities and the water
ion-exchange
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