Civil Engineering Reference
In-Depth Information
Table 5.4
Parameters of thermal analysis, PPy content determined by gravimetric analysis
and electrical conductivity of pure components and composites. Reproduced from [62] with
permission of Elsevier.
Samples
Py
content
(mol L
-1
)
Onset
temp. (°C)
Residue(%)
PPy content
-1
(%)
Electrical
conductivity
(S cm
-1
)
BC
-
285
22.0±1.5
-
1.8
×
10
-13
PPy
.
APS
-
218
56.7±1.4
-
1.3
×
10
-2
PPy
.
FeCl
3
-
175
60.7±1.7
-
3.2
×
10
0
BC/PPy
.
APS
0.01
265
25.9±2.8
12.0±2.0
7.8
×
10
-7
BC/PPy
.
APS
0.03
265
29.6±2.1
23.3±1.5
2.5
×
10
-5
CB/PPy
.
APS
0.05
265
32.5±2.9
33.1±2.5
1.2
×
10
-2
BC/PPy
.
FeCl
3
0.01
240
46.6±3.4
49.6±3.3
3.7
×
10
-3
BC/PPy
.
FeCl
3
0.03
230
57.8±3.6
73.3±2.5
1.1
×
10
-1
BC/PPy
.
FeCl
3
0.05
230
60.2±3.9
80.0±2.0
2.7
×
10
0
a
Gravimetric analysis.
BC/ PPy·APS composite. h ey explained this behavior by three main reasons: (i) the
highest electrical conductivity of PPy·FeCl
3
coating layer; (ii) BC/PPy·FeCl
3
composite
showed higher PPy content than those found for BC/PPy·APS system at the same mono-
mer concentration; and i nally, (iii) morphological dif erences between BC/PPy·FeCl
3
and BC/PPy·APS composites, as seen in SEM micrographs. h is work thus showed that
the oxidative polymerization of pyrrole in a bacterial cellulose (BC) hydrogel can be an
ef ective way to develop novel nanocellulose-based electrically active materials which
can be explored for new technological applications.
5.5.3
Nanostructured Porous Materials for Drug Delivery or as Bioactive
Compounds
Lacerda
et al.
[63] prepared novel nanostructured composite materials from bacte-
rial cellulose membranes (BC) and acrylate polymers by
in-situ
atom transfer radical
polymerization (ATRP). h e BC membranes were i rst functionalized with initiating
sites by reaction with 2-bromoisobutyryl bromide (BiBBr), and then polymerization of
methyl methacrylate (MMA) and n-butylacrylate (n-BA) was carried out in presence
of catalysts copper (I) bromide and N, N, N
′
, N
″
, N
″
-pentamethyldiethylenetriamine
(PMDETA), shown in Figure 5.8.
h e resulting nanocomposites showed high hydrophobicity showing contact angles
with water up to 134°C, good thermal stability with initial degradation temperature in
the range of 241−275 °C, and higher l exibility than the unmodii ed BC membranes [63].
