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%.

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.

Ring-opening polymerization of ∈-caprolactone was carried out smoothly and effectively with constant microwave powers of 170, 340, 510, and 680 W, respectively, with a microwave oven at a frequency of 2.45GHz. The temperature of the polymerization ranged from 80 to 210℃. Poly (∈-caprolactone) (PCL) with a weightaverage molar mass (Mw) of 124,000g/mol and yield of 90% was obtained at 680W for 30min using 0.1%(mol/mol) stannous octanoate as a catalyst. When the polymerization was catalyzed by 1% (w/w) zinc powder, the Mw of PCL was 92,300g/mol after the reaction mixture was irradiated at 680W for 270min.

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.