Patent ID: 8461265

Claim:
A method of producing a triblock copolymer, wherein one or more cyclic esters selected from the group consisting of lactides, glycolides and lactones are subjected to ring-opening polymerization under the presence of oligoolefin containing hydroxyl groups at both ends, represented by the following general formula (iv) wherein each R 1 is independently selected from the group consisting of H, —CH 3 , —C 2 H 5 , and —CH 2 CH(CH 3 ) 2 , and n represents an integer of 10 to 1000, the method comprising, as steps of obtaining the oligoolefin containing hydroxyl groups at both ends: melting one or more polyolefins selected from the group consisting of polypropylenes, poly-1-butenes, ethylene/propylene copolymers, ethylene/1-butene copolymers, propylene/1-butene copolymers, and poly-4-methyl-1-pentenes; thermally decomposing the melt under reduced pressure while subjecting the melt to bubbling with an inert gas; and subsequently hydroxylating the product of the thermal decomposition.