Polyacrylamide and its derivatives for oil recovery

 
Samples 
PVA (g) 
AM (g) 
MBAM (g) 
Glutaraldehyde (g) 
Water (g) 
Pure PAM 
0 
30 
0.05 
0 
70 
2% PVA/PAM 
0.6 
30 
0.05 
0.0006 
69.3 
10% PVA/PAM 
3 
30 
0.05 
0.003 
67 
15% PVA/PAM 
4.5 
30 
0.05 
0.0045 
65.4 
 

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174 
Fig. 2 
FTIR of (a) Pure PAM;(b) PVA-2%/PAM IPN; (c) PVA-10%/PAM IPN; (d) 
PVA-15%/PAM IPN; (e) Pure PVA 
Infrared spectroscopy is a useful technique in characterizing composition of 
materials. Figure 2(a) indicates the spectrum of pure PAM; Figures 2(b) thru (d) display 
the spectra of PAM/PVA IPNs of different PVA concentration; and Figure 2(e) shows the 
bands of PVA. A broad absorption band at 3395cm
–1
and 3198 cm
–1
are due to stretch 
vibrations of the N-H group.
The characteristic peaks at 1670 cm
-1
, 1415 cm
-1
are 
vibrations of the C=O (amide I) and C-N, respectively. The absorptions at 2940 cm
-1
, 
2863 cm
-1 
and 1450 cm
-1
reflect the vibrations of -CH
2
-. In the spectrum of pure PVA, 
3360 cm
-1
, 1441 cm
-1
, 1096 cm
-1
are due to the vibrations of the O-H and C-O of 
secondary alcohol. In the case of PAM/PVA IPNs, the absorption at 1430 cm
-1
split into 
two bands at 1451 and 1415 cm
-1
, and the peak at 1096 cm
-1
moved toward lower 
frequency. A new absorption band due to C–O–C stretching vibration at 1179 cm
-1
appears. The appearance of the ether group is assigned to intermolecular and 
intramolecular self-crosslinking.[41] It should be noted that the crystallization-associated 

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175 
band of PVA at 1143 cm
−1
was not present in FTIR spectra of PAM/PVA IPNs, 
supporting the transition of PVA from crystalline to amorphous structure.[36, 38, 50] 
(a)
(b)
Fig. 3 
Scanning electron micrographs of PAM hydrogel and PAM/PVA IPN 
hydrogel.(a) PAM hydrogel network; (b) PAM/PVA (10%) IPN hydrogel. The PVA 
appears as less porous ropes dispersed within surrounding porous PAM hydrogel
 
Porosity correlates with mechanical performance of a polymer matrix and affects 
the ability to apply the polymer, e.g., in the encapsulation of other materials. The as-
synthesized PAM network hydrogel and PAM/PVA IPNs had highly porous structures 
upon freeze drying (Figure 3), which would suggest effective absorption of water. The 

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176 
pore diameters of PAM (Figure 3a) were reduced in size as the secondary polymer 
network was added (Figure 3b). The SEM micrographs clearly illustrate different 
morphology when PVA was added into system. From Figure 3b, the IPN gels exhibited 
an obvious secondary network. In their work on PAM/PVA semi IPNs, Mishra et al. [40, 
42] reported linear PVA polymer without further crosslinking was observed embedded 
into the polyacrylamide network. However, no obvious porous structure was observed in 
their SEM micrographs.[51]