Patent ID: 9512268
Filing Date: 2016-12-06
CPC Classification: C08G,C08L

Claim Text:
1. A process for preparing a copolymer comprising providing a first cyclic ester having a first ring size from 4 to 11 atoms and a second cyclic ester having a second ring size from 12 to 40 atoms and subjecting the first and second cyclic esters to ring-opening copolymerization using as catalyst a compound of formula I wherein M is a trivalent metal selected from the group consisting of aluminium, titanium, vanadium, chromium, manganese, cobalt, yttrium, scandium, and lanthanides; X and X′ are both a heteroatom and may be the same or different; Y and Y′ are independently selected from the group consisting of O, N, S and P; Z is selected from the group consisting of hydrogen, borohydrides, aluminium hydrides, carbyls, silyls, hydroxides, alkoxides, aryloxides, carboxylates, thiocarboxylates, dithiocarboxylates, carbonates, carbamates, guanidates, amides, thiolates, phosphides, hydrazonate, imide, cyanide, cyanate, thiocyanate, azide, nitro, siloxides and halides; L1 is an organic moiety linking X and Y; L2 is an organic moiety linking X′ and Y′; L1 and L2 are the same or different; L3 is an organic moiety linking Y and Y′ and has a chain length between Y and Y′ of at least 2 atoms; and wherein said copolymer has a randomness of at least 0.5.