stable reaction of about 17 mins each time adding 80 ml methanol and putting into a refrigerator with u2212 30 u00b0 c for 4 h then collecting the precipitation by filtering and putting into a vacuum drying chamber for 24 h after natural air drying the precipitation and a purified poly u03b4 valerolactone may be obtained through analytic determination of the product the molecule weight are 3226 g mol 3300 g mol the molecule weight distribution are 1 128 1 115 the conversion rate is 92 the selectivity for sulfydryl are 92 93 embodiment 3 employing the immobilized enzyme micro reactor for synthetizing the mercapto functional poly u03b5 caprolactone filling 1 18 g immobilized enzyme novozyme435 into the micro channel which is rinsed by the toluene after re steaming dehydration to remove the air and water in the device adding 4 5656 g u03b5 caprolactone 0 5379 g 0 1074 g 0 06712 g 0 05370 g 6 mercapto 1 hexanol and 5 3 ml toluene solution into an ampoule bottle after dehydration under 500 high temperature and air exchanging for three times transferring into a injector after shaking evenly controlling the flow rate as 0 6033 ml min 0 0362 ml min 0 03017 ml min 0 01508 ml min respectively then inputting the mixed solution into the immobilized enzyme micro reaction channel for polymerization under 60 a poly u03b5 caprolactone reaction solution of 2.