Comparative Properties of Ethyl, n -Butyl, and n -Octyl Cyanoacrylate Bioadhesives Intended for Wound Closure - Biologically Responsive Biomaterials for Tissue Engineering - page 99

ECN Polymer

0.6

0.4

0.2

0.0
0.6

BCN Polymer

0.4

0.2

-0.0

0.5

OCN Polymer

0.4
0.3
0.2
0.1
0.0

3000 2000 1000

Wavenumber (cm -1 )

Fig. 5.9 ATR-IR spectra of the cyanoacrylate polymers

contains monomer and some dimmers (17.8 wt% is lost at 157 °C), and the OCN
has only a minor content of monomer (only 25.3 wt% is lost at 126 °C) and shows
four additional decompositions (Fig 5.8a , b; Table 5.5 ).
These results are in agreement with recent literature [ 3 ] that also described the
existence of different decompositions in the TGA thermograms of BCN polymer
ascribed to the existence of different structures in the polymer.

5.3.2 Characterization of the Cyanoacrylate Polymers

Cyanoacrylate monomers were polymerized at room temperature by adding water.
The properties of the resulting cyanoacrylate polymers were characterized and com-
pared with those of the monomers to establish the changes produced during
polymerization.
Figure 5.9 shows the ATR-IR spectra of the cyanoacrylate polymers.
In general, the assignment of the main IR bands is similar to that of the mono-
mers (Table 5.2 ), although the relative intensity of the bands is different and two
new distinct intense bands at 856 and 1,240 cm −1 due to new C − O − C groups appear
after polymerization of the cyanoacrylate monomers. As expected, the intensity of
the CH 2 group decreases by increasing the length of the alkyl hydrocarbon chain of
the cyanoacrylate and because of the polymerization the intensity of the band at
2,239 cm −1 due to the cyanoacrylate group is strongly reduced.
Figure 5.10 compares as typical example two significant regions of the ATR-IR
spectra of the ECN monomer and polymer. The polymerization produces the disap-
pearance of the C=C bands at 1,615 and 3,128 cm −1 as the polymerization of the