L-Dpolylactide copolymers with controlled morphology

• US 5,270,400 A
• Filed: 12/31/1991
• Issued: 12/14/1993
• Est. Priority Date: 12/31/1991
• Status: Expired due to Term

• Current Assignee: NatureWorks LLC (Cargill, Inc. (Agricultural Services Division))
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Spinu, Maria
• Primary Examiner(s): Seidleck, James J.
• Assistant Examiner(s): Hamilton, III, Thomas
• Application Number:
  US07/816,433
• Time in Patent Office: 714 Days
• Field of Search: 525/411, 528/354, 528/357
• US Class Current: 525/411
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08G 63/664 derived from hydroxy carboxylic acids

Abstract

Linear block copolymers are disclosed. The polymers comprise a plurality of alternating polymeric blocks of amorphous copolymers of L-lactide and D-lactide with semicrystalline blocks of either L-lactide homopolymer or D-lactide homopolymer. The molecular weight can be built up by either of two techniques. The first technique is to use a chain extending agent such as a diacyl chloride or a diisocyanate to link a plurality of the preformed block copolymers. The second technique is to polymerize additional alternating amorphous and semicrystalline onto the original alternating block copolymers.

Claims

1. A copolymer of the formula HOBAIABOH where A is a copolymer of 10 to 90 weight percent L-lactide and 90 to 10 weight percent D-lactide, B is a polylactide formed from 98 to 100 weight percent L-lactide or 98 to 100 weight percent D-lactide, and --I-- is the residue of a diamine or diol containing 2 to 100 carbon atoms.

2. The copolymer of claim 1 wherein copolymer segments A have a number average molecular weight of 500 to 20,000.

3. The copolymer of claim 2 wherein polymer segments B have a number average molecular weight of 1,000 to 40,000.

4. The copolymer of claim 3 wherein the copolymer segments A are 15 to 85 weight percent L-lactide units and 85 to 15 weight percent D-lactide units.

5. The copolymer of claim 4 wherein --I-- has the formula (OR)_n where --R-- is an alkylene group containing 2 to 6 carbon atoms and n is 2 to 20.

6. The copolymer of claim 5 wherein --R-- is an alkylene group containing 4 carbon atoms.

7. A copolymer of the formula HO(BA)_m I(AB)_m OH where A is a copolymer of 10 to 90 weight percent L-lactide and 90 to 10 weight % D-lactide, B is a polylactide formed from 98 to 100 weight percent L-lactide or 98 to 100 weight percent D-lactide, m is 2 to 10, and --I-- is the residue of a diamine or diol containing 2 to 100 carbon atoms.

8. The copolymer of claim 7 wherein copolymer segments A have a number average molecular weight of 500 to 20,000.

9. The copolymer of claim 8 wherein polymer segments B have a number average molecular weight of 1,000 to 40,000.

10. The copolymer of claim 9 wherein the copolymer segments A are 15 to 85 weight percent L-lactide units and 85 to 15 weight percent D-lactide units.

11. The copolymer of claim 10 wherein --I-- has the formula (OR)_n wherein --R-- is an alkylene group containing 2 to 6 carbon atoms and n is 2 to 20.

12. The copolymer of claim 11 wherein --R-- is an alkylene group containing 4 carbon atoms.