Polyacrylamide and its derivatives for oil recovery

Fig. 6. 
(a) 
1
H NMR of ocadecylacrylamide (b) 
1
H NMR and (c)
13
C NMR spectra of 
poly-(acrylamide-
co
-octadecylacrylamide). For liquid 1H NMR, poly-(acrylamide-co-
octadecylacrylamide) with 2 mol.-% octadecylacrylamide. For solid 13C NMR, poly-
(acrylamide-co-octadecylacrylamide) with 4 mol.-% octadecylacrylamide.
 

---

129 
Absorptions of C=C and C=O stretching vibration show up at 3037 cm
-1
and 1672 
cm
-1 
respectively. In the spectra of copolymer: the bands around 2925 cm
-1
, 2854 cm
-1
; 
1453 cm
-1
are owing to stretch vibrations of C-H; the characteristic peaks at 1665 cm
-1
and 1324 cm
-1
are vibrations of C=O and C-N. 
Synthesized ocadecylacrylamide and the copolymer structure was determined by 
1
H NMR and
13
C NMR, see Figure 6. Due to high viscosity and poor solubility, liguid 
1
H 
NMR was conducted at 60 
°
C for hydorphobically modified polyacrylamide with 2 mol.-
% aklyacrylamide. Solid 
13
C NMR was taken of polyacrylamide with 4 mol.-%
aklyacrylamide. The assignments of each peak are in agreement with the literature 
data.[45, 46] 
3.3. Effect of Hydrophobe Content 
Thermal properties of the poly (acrylamide-co-octadecylacrylamide) were 
characterized by TGA. According to Figure 7, crude dry product were obtained by 
removing free water and solvent isothermally at 105 º
C. Bulk water and solvents were 
about 5~9 -% mass of samples with 0~2 mol-% hydrophobe. From 110 º
C to 220 º
C, the 
weight loss during this period is caused by the loss of bonding water and solvent during 
the polymerization and purification supposedly. Obviously, copolymer with more 
hydrophobe had more weight loss during this period. Because the incorporated 
hydrophobe can break the compact packing of pure PAM, which can created more free 
space to absorb polar water and solvent during the purification or from the environment. 
Furthermore, the bonded water and solvent which is more close to the hydrophobe would 

---

130 
be lost at lower temperature, resulting in some flocculation on the curves (red dash 
circled area in Fig. 7.).
There are two main thermal degradations of the copolymer, typical of 
polyacrylamide. The first degradation temperature (T
d
) is onset at 270 º
C. The 
degradation evolves ammonia from thermal imidization of polyacrylamide or absorbed 
mineral oil in microspheres.[47, 48] The main weight loss onset at 380 º
C, which is 
resulted from the degradation of polymer backbone.