Degradation and erosion behaviour of cyanoacrylate tissue adhesives

• Main Author: Cai, Q.
• Published: University of Cambridge 2006
• Subjects: 612
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597212

In this dissertation, the degradation and erosion behaviour in phosphate buffered saline solution at 37°C of eight different cyanoacrylate polymers has been investigated. The mass loss, water gain and pH change have been measured and structural changes have been studied using Fourier transform infrared spectroscopy and nuclear magnetic resonance absorbance. Morphological changes in these polyesters pre- and post<i>-in vitro</i> experiments was studied by scanning electron microscopy. Cell responses to selected cyanoacrylate polymers were compared in terms of direct contact and indirect extraction tests. In addition, these polymer materials were characterised using differential scanning calorimetry, thermogravimetric analysis, gel permeation chromatography and mechanical analysis. The experimental results revealed that poly (alkoxyalkyl-α-cyanoacrylates) had generally higher degradation rates than poly (alkyl-α-cyanoacrylates). The length of the alkoxyalkyl or alkyl side chain had an effect on the polymer degradation, namely, the longer the side chain, the slower the degradation rate. The addition of polymethylmethacrylate made poly (ethyl-α-cyanoacrylates) more resistant to degradation. Moreover, not only surface but also bulk hydrolysis proceeds during the course of polymer degradation and erosion. The experimental data further confirmed that the major chemical degradation is the hydrolytic degradation of polymer backbone. However, formaldehyde is not the main degradation produce of the polymer hydrolysis. The degradation fragments continued to hydrolyse into carboxylic acid salts, which render the surrounding medium relatively acidic. With the higher degradation rates, the alkoxyalkyl polymers made the surrounding medium more acidic than the alkyl polymers, which could explain why the alkoxyalkyl polymers elicited a more unfavourable cell response than the alkyls.