Photochemically cross-linked poly(ε-caprolactone) with accelerated hydrolytic degradation (original) (raw)

Porous poly(ε-caprolactone) (PCL) scaffolds were fabricated using the high internal polymerization emulsion (HIPE) technique. Bis(ε-caprolactone-4-yl) (BCY) was utilized as crosslinker. The crosslinking density and the volume fraction of the dispersed phase were varied in order to study the potential effect of these parameters on the hydrolytic degradation at 37 °C and 60 °C. After different hydrolysis times the remaining solid samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), while the degradation products in the aqueous aging solutions were analyzed by laser desorption ionization-mass spectrometry (LDI-MS). The effect of temperature on the degradation process and release of degradation products was, as expected, significant. The temperature effect was also shown by FTIR analysis that displayed a pronounced increase in the intensity of the hydroxyl-group absorption band after 70 days of hydrolysis at 60 °C indicating sig...

Poly(ε–caprolactone) (PCL), crosslinked by gamma rays in a super cooled state, had high thermal stability, better transparency and heat shrink property. Biodegradation of such PCL was carried out using lipase AK enzyme in a phosphate buffer solution having a pH of 7.0. The enzymatic degradation was remarkably affected by reaction temperature. Preferable temperatures for enzymatic degradation were 50°C for uncrosslinked PCL and 55°C for crosslinked. The enzymatic degradation rate of crosslinked PCL is slower than that of the uncrosslinked due to network structure. However, it was confirmed that enzymatic degradation occurs even for high crosslink density of PCL such as 80% of gel content.

The UV-light degradation of polyethylene oxide (PEO) in aqueous solution was investigated operating under long wavelengths (λ>300nm) at 20°C in different pH conditions varying from 2.3 to 12.0 and at two different concentrations. Thermo-oxidation experiments on PEO aqueous solution at 50°C are also reported and compared to photo-oxidation results. The formation of oxidation products was followed by infrared analysis of deposits obtained by evaporation of aliquots of irradiated polymer solution. Photo-oxidation led to formates and esters but a third product was also identified, formic acid ions formed by partial hydrolysis of formates. The degradation of PEO in water led to the acidification of the aquatic medium. Size exclusion chromatography (SEC) was used to monitor the changes in molar weight and intrinsic viscosity with irradiation time. It was shown that the photo-oxidation produced a dramatic decrease of the average molar weights which is more important in acidic medium. To...