Method for making copolymers of lactide and a 1:4-3:6 dianhydrohexitol

1. A process comprising polymerizing a 1:4-3:6-dianhydrohexitol, lactide and a carbonate precursor in one step by forming a mixture of the 1:4-3:6-dianhydrohexitol, lactide, carbonate precursor, and at least one polymerization catalyst, and subjecting the mixture to polymerization conditions including an elevated temperature and a subatmospheric pressure to form a polyester-carbonate containing randomly distributed dianhydrohexitol carbonate repeating units and lactide repeating units.

2. The process of claim 1 , wherein the molar ratio of the lactide to the 1:4-3:6-dianhydrohexitol is from 5:1 to 1:2.

3. The process of claim 2 , wherein the polyester-carbonate has a T g of 75° C. to 110° C.

4. The process of claim 3 , wherein the 1:4-3:6-dianhydrohexitol is isosorbide.

5. The process of claim 4 , wherein the molar ratio of the lactide to the 1:4-3:6-dianhydrohexitol is from 5:1 to 1:1.

6. The process of claim 1 wherein the carbonate precursor has the structure

wherein each X is independently halogen or an alkoxy or aryloxy group having up to 12 carbon atoms.

7. The process of claim 6 , wherein the carbonate precursor is diphenylcarbonate.

8. The process of claim 1 , wherein the polyester-carbonate has an M n of from 10,000 to 100,000.

9. The process of claim 1 , further comprising coupling the polyester-carbonate with a difunctional coupling agent.

10. The process of claim 9 , wherein the coupled polyester-carbonate has an M n of from 50,000 to 150,000.

11. The process of claim 9 , wherein the difunctional coupling agent is a diisocyanate compound, a diepoxide, a dicarboxylic acid, a dianhydride of a tetracarboxylic acid, or a compound having two primary or secondary amino groups.