<s>
Polyaniline	B-Algorithm
(	O
PANI	O
)	O
is	O
a	O
conducting	B-Algorithm
polymer	I-Algorithm
and	O
organic	B-Algorithm
semiconductor	I-Algorithm
of	O
the	O
semi-flexible	O
rod	O
polymer	O
family	O
.	O
</s>
<s>
Polyaniline	B-Algorithm
is	O
one	O
of	O
the	O
most	O
studied	O
conducting	B-Algorithm
polymers	I-Algorithm
.	O
</s>
<s>
He	O
developed	O
the	O
first	O
commercially	O
successful	O
route	O
to	O
the	O
dye	O
called	O
Aniline	B-Algorithm
black	I-Algorithm
.	O
</s>
<s>
The	O
first	O
definitive	O
report	O
of	O
polyaniline	B-Algorithm
did	O
not	O
occur	O
until	O
1862	O
,	O
which	O
included	O
an	O
electrochemical	O
method	O
for	O
the	O
determination	O
of	O
small	O
quantities	O
of	O
aniline	O
.	O
</s>
<s>
Polymerized	O
from	O
the	O
inexpensive	O
aniline	O
,	O
polyaniline	B-Algorithm
can	O
be	O
found	O
in	O
one	O
of	O
three	O
idealized	O
oxidation	O
states	O
:	O
</s>
<s>
Leucoemeraldine	B-Algorithm
with	O
n	O
=	O
1	O
,	O
m	O
=	O
0	O
is	O
the	O
fully	O
reduced	O
state	O
.	O
</s>
<s>
Pernigraniline	B-Algorithm
is	O
the	O
fully	O
oxidized	O
state	O
(	O
n	O
=	O
0	O
,	O
m	O
=	O
1	O
)	O
with	O
imine	O
links	O
instead	O
of	O
amine	O
links	O
.	O
</s>
<s>
Studies	O
have	O
shown	O
that	O
most	O
forms	O
of	O
polyaniline	B-Algorithm
are	O
one	O
of	O
the	O
three	O
states	O
or	O
physical	O
mixtures	O
of	O
these	O
components	O
.	O
</s>
<s>
The	O
emeraldine	B-Algorithm
(	O
n	O
=	O
m	O
=	O
0.5	O
)	O
form	O
of	O
polyaniline	B-Algorithm
,	O
often	O
referred	O
to	O
as	O
emeraldine	B-Algorithm
base	O
(	O
EB	O
)	O
,	O
is	O
neutral	O
,	O
if	O
doped	O
(	O
protonated	O
)	O
it	O
is	O
called	O
emeraldine	B-Algorithm
salt	O
(	O
ES	O
)	O
,	O
with	O
the	O
imine	O
nitrogens	O
protonated	O
by	O
an	O
acid	O
.	O
</s>
<s>
Emeraldine	B-Algorithm
base	O
is	O
regarded	O
as	O
the	O
most	O
useful	O
form	O
of	O
polyaniline	B-Algorithm
due	O
to	O
its	O
high	O
stability	O
at	O
room	O
temperature	O
and	O
the	O
fact	O
that	O
,	O
upon	O
doping	O
with	O
acid	O
,	O
the	O
resulting	O
emeraldine	B-Algorithm
salt	O
form	O
of	O
polyaniline	B-Algorithm
is	O
highly	O
electrically	O
conducting	O
.	O
</s>
<s>
Leucoemeraldine	B-Algorithm
and	O
pernigraniline	B-Algorithm
are	O
poor	O
conductors	O
,	O
even	O
when	O
doped	O
with	O
an	O
acid	O
.	O
</s>
<s>
The	O
colour	O
change	O
associated	O
with	O
polyaniline	B-Algorithm
in	O
different	O
oxidation	O
states	O
can	O
be	O
used	O
in	O
sensors	O
and	O
electrochromic	O
devices	O
.	O
</s>
<s>
Polyaniline	B-Algorithm
sensors	O
typically	O
exploit	O
changes	O
in	O
electrical	O
conductivity	O
between	O
the	O
different	O
oxidation	O
states	O
or	O
doping	O
levels	O
.	O
</s>
<s>
Treatment	O
of	O
emeraldine	B-Algorithm
with	O
acids	O
increases	O
the	O
electrical	O
conductivity	O
by	O
up	O
to	O
ten	O
orders	O
of	O
magnitude	O
.	O
</s>
<s>
Undoped	O
polyaniline	B-Algorithm
has	O
a	O
conductivity	O
of	O
S/m	O
,	O
whereas	O
conductivities	O
of	O
S/m	O
can	O
be	O
achieved	O
by	O
doping	O
to	O
4%	O
HBr	O
.	O
</s>
<s>
The	O
same	O
material	O
can	O
be	O
prepared	O
by	O
oxidation	O
of	O
leucoemeraldine	B-Algorithm
.	O
</s>
<s>
Although	O
the	O
synthetic	O
methods	O
to	O
produce	O
polyaniline	B-Algorithm
are	O
quite	O
simple	O
,	O
the	O
mechanism	O
of	O
polymerization	O
is	O
probably	O
complex	O
.	O
</s>
<s>
The	O
formation	O
of	O
leucoemeraldine	B-Algorithm
can	O
be	O
described	O
as	O
follows	O
,	O
where	O
 [ O ] 	O
is	O
a	O
generic	O
oxidant	O
:	O
</s>
<s>
(	O
Per	O
)	O
nigraniline	B-Algorithm
is	O
prepared	O
by	O
oxidation	O
of	O
the	O
emeraldine	B-Algorithm
base	O
with	O
a	O
peracid	O
:	O
</s>
<s>
The	O
synthesis	O
of	O
polyaniline	B-Algorithm
nanostructures	O
is	O
facile	O
.	O
</s>
<s>
Using	O
surfactant	O
dopants	O
,	O
the	O
polyaniline	B-Algorithm
can	O
be	O
made	O
dispersible	O
and	O
hence	O
useful	O
for	O
practical	O
applications	O
.	O
</s>
<s>
Bulk	O
synthesis	O
of	O
polyaniline	B-Algorithm
nanofibers	O
has	O
been	O
researched	O
extensively	O
.	O
</s>
<s>
A	O
multi-stage	O
model	O
for	O
the	O
formation	O
of	O
emeraldine	B-Algorithm
base	O
is	O
proposed	O
.	O
</s>
<s>
In	O
the	O
first	O
stage	O
of	O
the	O
reaction	O
the	O
pernigraniline	B-Algorithm
PS	O
salt	O
oxidation	O
state	O
is	O
formed	O
.	O
</s>
<s>
In	O
the	O
second	O
stage	O
pernigraniline	B-Algorithm
is	O
reduced	O
to	O
the	O
emeraldine	B-Algorithm
salt	O
as	O
aniline	O
monomer	O
gets	O
oxidized	O
to	O
the	O
radical	O
cation	O
.	O
</s>
<s>
Polyaniline	B-Algorithm
is	O
typically	O
produced	O
in	O
the	O
form	O
of	O
long-chain	O
polymer	O
aggregates	O
,	O
surfactant	O
(	O
or	O
dopant	O
)	O
stabilized	O
nanoparticle	O
dispersions	O
,	O
or	O
stabilizer-free	O
nanofiber	O
dispersions	O
depending	O
on	O
the	O
supplier	O
and	O
synthetic	O
route	O
.	O
</s>
<s>
Surfactant	O
or	O
dopant	O
stabilized	O
polyaniline	B-Algorithm
dispersions	O
have	O
been	O
available	O
for	O
commercial	O
sale	O
since	O
the	O
late	O
1990s	O
.	O
</s>
<s>
Polyaniline	B-Algorithm
and	O
its	O
derivatives	O
are	O
also	O
used	O
as	O
the	O
precursor	O
for	O
the	O
production	O
of	O
N-doped	O
carbon	O
materials	O
through	O
high-temperature	O
heat	O
treatment	O
.	O
</s>
<s>
Printed	O
emeraldine	B-Algorithm
polyaniline-based	O
sensors	O
have	O
also	O
gained	O
much	O
attention	O
for	O
widespread	O
applications	O
where	O
devices	O
are	O
typically	O
fabricated	O
via	O
screen	O
,	O
inkjet	O
or	O
aerosol	O
jet	O
printing	O
.	O
</s>
