Biodegradable Poly-pentadecalactone (PDL) Synthesis via Synergistic Lipase and Microwave Catalysis

Abstract A large nu mber of currently used synthetic biodegradable polymers in bio med ical engineering applications are polyesters based materials and thus research on the synthesis, properties, manufacturing and processing of aliphatic polyesters continues to be of great importance. Poly -ω-pentadecalactone (PPDL) a lactone based ring opening polymer has good mechanical properties and the presence of hydrolysable ester linkages along the poly mer chain making it desirable as a biodegradable material for diversified bio med ical engineering applications. In this paper we report the formation of PPDL using the synergistic effects of lipase and microwave (MW) technology. The effect of reaction time on the PPDL poly mer chain growth has been investigated. PPDL have been formed using lipase and MW irradiation at varying reaction time intervals (30-240 mins). Synergistic MW and lipase catalyzed poly merization of PPDL gave a number average molecular weight (Mn) of 24,997 g/ mol and a polydispersity index (PDI) of 1.93 in 240 mins as compared to Mn of 8,060 g/mo l and PDI of 2.17 using lipase and tradit ional heating. Thermal characterizat ion of PPDL fo rmed using MW and lipase catalysis showed that MW did not have a detrimental effect on the thermal properties of the poly mer obtained

Spectroscopic Evaluations of Interfacial Oxidative Stability of Phosphonic Nanocoatings on Magnesium

Magnesium (Mg), and its alloys, is being investigated for its potential biomedical applications for its use as a biodegradable metal. However surface modification strategies are needed to modify the surface of the Mg alloy for its applicability in these applications. Self-assembled monolayers (SAMs) have been investigated as a coating strategy on magnesium for biomedical applications. In this report we evaluate the oxidative interfacial stability of phosphonic nanocoatings on magnesium using spectroscopic techniques. Self-assembled mono-/multilayers (SAMs) of octadecylphosphonic acid (ODPA) were formed on the native oxide layer of magnesium alloy using solution deposition technique. The SAMs modified Mg alloy and its oxidative stability were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). FTIR studies indicated mono-/bidentate bonding of the phosphonic SAMs to the Mg alloy surface. XPS confirmed SAM formation showing presence of “P” peaks while consequently showing decrease in peak intensity of Mg peaks. XPS analysis of the phosphonate peaks showed consistent presence of this peak over a period of 21 days. AFM images showed consistent coverage of the Mg alloy over a period of 21 days. The results collectively confirm that the monolayers are stable under the chosen oxidative study