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.

polymer (Mw3000g mol 1 with Mw/Mn 1.2) was obtained by the copper-catalyzed nitrogenelimination of allyl diazoacetate. Its structure was determined as poly (carballyloxycarbene) (PCACB) by 1H and 13C NMR and IR spectroscopy.

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.

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

The ring-opening polymerization of ∈-caprolactone (∈-CL), initiated by carboxylic acids such as benzoic acid and chlorinated acetic acids under microwave irradiation, was investigated; with this method, no metal catalyst was necessary. The product was characterized as poly (∈-caprolactone) (PCL) by 1H NMR spectroscopy, Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and gel permeation chromatography. The polymerization was significantly improved under microwave irradiation. The weight-average molecular weight (Mw) of PCL reached 44,800 g/mol, with a polydispersity index [weight-average molecular weight/number-average molecular weight (Mw/Mn)] of 1.6, when a mixture of ∈-CL and benzoic acid (25/1 molar ratio) was irradiated at 680W for 240min, whereas PCL with Mw 12,100 and Mw/Mn 4.2 was obtained from the same mixture by a conventional heating method at 210℃ for 240min. A degradation of the resultant PCL was observed during microwave polymerization with chlorinated acetic acids as initiators, and this induced a decrease in Mw of PCL. However, the degradation was hindered by benzoic acid at low concentrations.