Biomedical Engineering Reference
In-Depth Information
8
Conductive or
Conjugated Polymers
as Artificial Muscles
8.1
INTRODUCTION
This chapter offers a brief presentation on the impact of conductive or conjugated
polymers to the general field of artificial and synthetic muscles. Certainly, the
pioneering work and discoveries of the three Noble laureates in chemistry in 2000—
Alan J. Heeger, (Noble Prize Lecture, 2001), Alan MacDiarmid (Noble Prize Lec-
ture, 2001), and Hideki Shirakawa (Noble Prize Lecture, 2001)—in the field of
conductive polymers and synthetic metals paved the way to current knowledge and
discoveries on conductive polymers, as can also evidenced in the early papers of
Shirakawa et al. (1977), Chiang et al. (1977, 1978); and McGehee and coworkers
in
in 1999.
Following Shahinpoor (who, as early as 1991, presented biomimetic robotic fish
equipped with ionic polymers as undulating fin and artificial muscles), Otero and
colleagues (1992a, 1992b) were the first to discuss the properties of polypyrrole as
a conductive polymer actuator that mimicked natural muscles and was named an
artificial muscle. They also discussed the electrochemomechanical phenomena
involved in such electrochemical reactions.
Twenty Years of Synthetic Metals
Conjugated polymers
, also known as
conducting polymers
, are distinguished by alternating single and double bonds
between carbon atoms on the polymer backbone. The conjugated polymer with the
simplest chemical structure is polyacetylene, shown in figure 8.1. Figure 8.2 depicts
the molecular structure of a more popular conductive polymer polypyrrole.
FIGURE 8.1
Simple structures of polyacetylene alternating single and double bonds between
carbon atoms.
H
H
H
H
N
N
N
N
N
H
N
H
N
H
N
H
FIGURE 8.2
Molecular structure of a simple polypyrrole conductive polymer.
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