Block copolymer of polyesters and polycarbonates and process for preparation thereof

A process for preparing a block copolymer of polyesters and polycarbonates comprising at least one of each of the units (I) and (II) having the general formulae:

• ##STR5## where the symbol * indicates an asymmetric carbon atom;
• R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are either a hydrogen atom or a methyl group;
• and m and n are each respective natural numbers ranging from 300 to 5,000, wherein said copolymer comprises block units of (I)-(II), (II)-(I), (I)-(II)-(I), (II)-(I)-(II), (I)-(II)-(X), or (II)-(I)-(X), wherein (I) and (II) are structural units as defined above, and (X) is a structural unit other than (I) or (II), the process comprising a repeatable sequence of steps of:
• a) ring-opening and polymerizing optically active .beta.-butyrolactones in the presence of a catalyst, whereby a reaction mixture is obtained;
• b) adding cyclic carbonates to said reaction mixture;
• and
• c) ring-opening and polymerizing said cyclic carbonates.

A process for preparing a block copolymer of polyesters and polycarbonates comprising a first moiety including at least one of each of the units (I) and (II) having the general formulae:

• ##STR6## where the symbol * indicates an asymmetric carbon atom;
• R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are either a hydrogen atom or a methyl group;
• and m and n are each respective natural numbers ranging from 300 to 5,000, wherein said copolymer comprises block units of (I)-(II), (II)-(I), (I)-(II)-(I), (II)-(I)-(II), (I)-(II)-(X), or (II)-(I)-(X), wherein (I) and (II) are structural units as defined above, and (X) is a structural unit other than (I) or (II), and a second moiety including either further polyesters of a formula corresponding to that of unit (I) or further polycarbonates of a formula corresponding to that of unit (II) but having but having a different monomer constituent from the first moiety, the process comprising a repeatable sequence of steps of:
• a) ring-opening and polymerizing optically active .beta.-butyrolactones in the presence of a catalyst, whereby a reaction mixture is obtained;
• b) adding cyclic carbonates to said reaction mixture;
• and
• c) ring-opening and polymerizing said cyclic carbonates;
• said process further comprising the step of:
• d) adding either optically active .beta.-butyrolactones or cyclic carbonates corresponding to the monomers of unit (II) but differing from those used for steps a) to c) and subsequently ring-opening and polymerizing the added .beta.-butyrolactones or cyclic carbonates;
• with steps a) to d) being repeatable.

Block copolymer of polyesters and polycarbonates comprising a first moiety including at least one of each of the units (I) and (II) having the general formulae:

• ##STR9## where the symbol * indicates an asymmetric carbon atom;
• R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are either a hydrogen atom or a methyl group;
• and m and n are each respective natural numbers ranging from 300 to 5,000, wherein said copolymer comprises block units of (I)-(II), (II)-(I), (I)-(II)-(I), (II)-(I)-(II), (I)-(II)-(X), or (II)-(I)-(X), wherein (I) and (II) are structural units as defined above, and (X) is a structural unit other than (I) or (II);
• and a second moiety including further polyesters of a formula corresponding to that of unit (I).

Block copolymer of polyesters and polycarbonates comprising a first moiety including at least one of each of the units (I) and (II) having the general formulae:

• ##STR10## where the symbol * indicates an asymmetric carbon atom;
• R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are either a hydrogen atom or a methyl group;
• and m and n are each respective natural numbers ranging from 300 to 5,000, wherein said copolymer comprises block units of (I)-(II), (II)-(I), (I)-(II)-(I), (II)-(I)-(II), (I)-(II)-(X), or (II)-(I)-(X), wherein (I) and (II) are structural units as defined above, and (X) is a structural unit other than (I) or (II);
• and a second moiety including further polycarbonates of a formula corresponding to that of unit (II) but having a different monomer constituent from the first moiety.