Comparative Properties of Ethyl, n -Butyl, and n -Octyl Cyanoacrylate Bioadhesives Intended for Wound Closure - Biologically Responsive Biomaterials for Tissue Engineering - page 103

Fig. 5.14 Single lap-shear strength values of pig skin/cyanoacrylate monomer/pig skin adhesive
joints. Values obtained 60 s after joint formation

by increasing the length of the alkyl hydrocarbon chain of the cyanoacrylate as a
consequence of the increase in its molecular weight. A cohesive failure in the adhe-
sive is always obtained in all adhesive joints.
Figure 5.14 shows the single lap-shear strength values of the pig skin/cyanoacry-
late adhesive joints. The shear strength values were obtained 60 s after joint forma-
tion. A similar trend in joint strength as that in Fig. 5.13 is obtained and comparable
adhesion is shown in the joints produced with the ethyl and n -butyl cyanoacrylate.
The values obtained are high and sufficient to maintain the tissues joined in
wound closure. A mixed failure (cohesive in the adhesion and adhesion to pig skin)
was obtained in all adhesive joints.

5.4 Conclusions

The increase in the length of the alkyl hydrocarbon chain in the cyanoacrylate
monomer increased the intensity of the CH 2 and CH 3 bands and decreased the inten-
sity of the C-O-C bands. Similarly, the intensity of the signals corresponding to the
protons of the C=C bond in the cyanoacrylate monomer decreased and the signal of
the CH 2 groups became less marked by increasing the length of the alkyl hydrocar-
bon chain. On the other hand, the signals corresponding to the C=C, C=O, and C≡N
groups displaced to higher values by increasing the length of the alkyl hydrocarbon
chain in the cyanoacrylate monomer. The TGA curves of the three cyanoacrylate
monomers show several decomposition steps, the first decomposition was found at
about 120 °C and the weight loss decreased by increasing the length of the alkyl
hydrocarbon chain. Whereas the ECN was mainly composed of monomer, the BCN
contained monomer and some dimmers, and the OCN had only a minor content of
monomer showing five thermal decompositions.
Polymerization of the monomers modified the chemical structure of the cyano-
acrylate. The polymerization produced the disappearance of the C=C bands as the
polymerization of the cyanoacrylate was produced in these C=C bonds. Furthermore,