Poly (∈-caprolactone) was blended with various polylactide-based polymers and processed to films by the solution casting method. Blends of 25/75, 50/50, 75/25, 90/10, and 95/5 (w/w) poly(∈-caprolactone)/poly-(L-lactide), a 95/5 (w/w) blend of poly(∈-caprolactone) with a poly (D-lactide), a 50/50 (w/w) poly (L-lactide)-poly (D-lactide) mixture, and a poly (L-lactide-co-∈-caprolactone) copolymer were considered comparatively. The various phase-separated films were allowed to degrade in the presence of Pseudomonas lipase, biodegradation being monitored by proton nuclear magnetic resonance, size exclusion chromatography, differential scanning calorimetry, X-ray diffraction, and environmental scanning electron microscopy. The formation of separated phases during solvent evaporation and their morphologies are discussed. The introduction of poly(L-lactide) dramatically decreased the degradation rate of poly(∈-caprolactone)/poly (Llactide) blends. The higher the percentage of poly(L-lactide), the slower the degradation, while the presence of cracks and increasing the lipase concentration acted in favor of the enzymatic degradation. Long-term enzymatic degradation of the various 95/5 blends was investigated over 480 h. The poly(∈-caprolactone) phase was enzymatically degraded by the lipase regardless of the blend type, the degradation rate depending on the nature of the co-components.

Poly(D,L-lactide) with a molar mass of 10 5g

Acid-initiated ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) was con-ducted under microwave imadiation (MI) at 2.45 GHz. At this frequency, metallic catalysts were no longer necessary, The effects of microwave power, imadiation time, ε-CL: acid molar ratio and acidity of acid on the polymerization were investigate. Both the rate of polymerization and the mollar mass of polymer obtained were enhanced in comparison with conventiona thermal method. Poly (ε-caprolactone) (PCL) with weight-average molar mass (Mw) over 12000g/mol and Mw/Mn below 1.6 was synthesized in the presence o carboxylic acids such as maleic acid (MA), succinic acid (SA) and adipic acid (AA). The polymerization was also carried out when the monoiner contained a certain amount of ibuprofen (IBU), by which, the IBU-PCL controlled release systern was prepared directly. The release of IBU from the systern was sustained from 12h to 9 days with IBU content in weight increasing from 5 to 20%. It seems that this is a prornising method to prepare drug controlled release systerns.

The micro construction of poly(e-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) blend films fabricated by solution casting under microwave irradiation was investigated by selective enzymatic degradation and scanning electron microscopy (SEM). The results were totally different from the blends obtained by conventional methods. The blend was more homogeneous and the PCL continuous phase more compact as no spherulites and tiny zone separation were observed from the film surface and no PCL network was observed inside the film, and the degradation of a PCL plank by Pseudomonas lipase was significantly retarded. The distributed PLLA micro spheres were enlarged and amorphous. The thermal behavior of the blend by microwave heating revealed that PCL and PLLA underwent a melting process, which induced the variations of the PCL phase and PLLA spheres.

The thermal effect of microwave energy on ε-caprolactone (CL) monomer and polymerization reaction mixture of CL with stannous octoate [Sn(Oct)2] intimately depended on the power level of microwaves and the mass scale of materials. When 10g of CL was heated by microwaves at a power of 680W, its temperature increased rapidly from 20 to 355℃ within 5 min after which it was self-regulated to keep constant at 360℃. Heat generation was observed when a polymerization reaction mixture of 10g CL with 0.1% (mol/mol) Sn (Oct) 2 was irradiated at 680W. The exothermic peak was recorded at 2-5min and its temperature was over 300℃, with the maximum at 343℃. During this period the ring-opening polymerization of CL occurred quickly, resulting in poly(ε-caprolactone) with weight-average molecular weight (Mw) of 123,000g/mol and yield of 95%.