Synthesis of polymers from cyclic diolides

A copolymer comprising Formula III:

• wherein:
• x is 10 to about 5,000;
• y is about 10 to about 5,000;
• n is 10-50;
• each R is (C1-C18)alkyl, (C1-C8)alkenyl, (C1-C8)alkynyl, benzyl, or aryl;
• the x block of Formula III comprises at least 95% isotactic triads with respect to the stereocenters of substituents R on the polymer chain, wherein the at least 95% isotactic triads (mm) have consecutive (R) stereochemical configurations or consecutive (S) stereochemical configurations;
• and
• the y block of Formula III comprises consecutive R groups having (R) and (S) configurations, consecutive R groups having (S) and (R) configurations, or consecutive R groups having stereochemical configurations the opposite of the main stereochemical configuration of the x block;
• wherein the polymer of Formula III is an isotactic-b-syndiotactic stereodiblock or stereotapered copolymer.

A copolymer comprising Formula IV:

• wherein:
• x is 10 to about 100;
• y is about 1 to about 100;
• k is about 1 to 16;
• n is 10 to about 5,000;
• R is (C1-C18)alkyl, (C1-C8)alkenyl, (C1-C8)alkynyl, benzyl, or aryl;
• and
• the x block of Formula IV comprises at least 9500 isotactic triads with respect to the stereocenters of substituents R on the polymer chain, wherein the at least 9500 isotactic triads (mm) have consecutive (R) stereochemical configurations or consecutive (S) stereochemical configurations.

A method for preparing an isotactic polymer of Formula I:

• wherein:
• n is about 10 to about 10,000;
• R is (C1-C18)alkyl, (C1-C8)alkenyl, (C1-C8)alkynyl, benzyl, or aryl;
• and
• Formula I comprises at least 95% isotactic triads with respect to the stereocenters of substituents R on the polymer chain, wherein the at least 95% isotactic triads (mm) have consecutive (R) stereochemical configurations or consecutive (S) stereochemical configurations;
• the method comprising contacting one or more monomers, an effective amount of a metal complex, and an alcohol initiator to initiate a ring opening polymerization reaction;
• wherein:
• the monomer is a monomer of Formula V:
• wherein R is as defined for Formula I;
• and
• the metal complex is a metal complex of Formula X:
• wherein:
• M is Sc, Y, or a lanthanide metal;
• Ligand is alkoxy, amide, or —N(SiRx3)2 wherein each Rx is H or alkyl, and at least two Rx groups are alkyl;
• Ra is H, alkyl, or phenyl;
• Rb is alkyl or phenyl;
• and
• Rc is alkyl or phenyl;
• or
• Rb and Rc together with the carbon atoms to which they are attached form a 5, 6, 7, or 8 membered cycloalkyl group;
• to thereby form the isotactic polymer of Formula I.