Chemistry Reference
In-Depth Information
Table 2
(continued)
Polyelectrolyte
(Abbreviation)
Repeating unit
Polyelectrolyte
(Abbreviation)
Repeating unit
Poly(ethylene-
imine)
(PEI)
Poly(vinyl amine)
(PVAm)
NH
CH
2
CH
2
CH
2
CH
n
n
NH
2
Poly(trimethyl
ammonium
methyl
methacrylate)
(PTMAC)
CH
3
CH
2
CH
n
CH
C
O
O
CH
2
N
+
CH
2
CH
Cl
-
CH
Poly(allylamino
hydrochloride)
(PAAm)
Poly(diallyldimethyl
ammonium chloride)
(PDADMAC)
CH
2
CH
CH
2
NH
2
CH
2
CH
H
2
C
CH
2
CH
CH
2
n
n
HCl
N
+
Cl
-
H
3
C
C
3
Poly(vinylbenzene
trimethyl
ammonium
chloride)
(PVBTMAC)
Poly(2-(meth-
acryloyloxy)
ethyl trimethyl
ammonium chloride)
(PMETAC)
CH
3
CH
2
CH
n
CH
2
CH
n
C
O
O
CH
2
H
3
C N
+
CH
3
H
2
C
CH
2
N
Cl
-
CH
3
+
Cl
-
H
3
C
CH
3
CH
3
formula. The abbreviation usually consists of two parts: one part stands for the
backbone and electrolyte group (cf. Table
2
), the other for the (approximate)
molecular mass. A polyelectrolyte material rarely consists of one single type of
molecule, but of a variety of molecules of different molecular masses.
In principle, a distribution function
f
(
M
) has to be used to characterize that material:
f
(
M
)
dM
is the fraction of polymers with a molecular mass between
M
dM/2
and
M
þ
dM/2
, with the normalization:
ð
1
f
ð
M
Þ
d
M
¼
:
1
(1)
0
However, as such distributions are difficult to determine, it is common practice
to characterize a polymer sample by the number-average (
M
n
) and the mass-
average (
M
w
) molecular masses, which are the first members in a series of
moments:
