Flame-retardant polylactic acid (PLA) by grafting through of phosphorus-containing polymers directly to PLA backbone

• US 9,187,597 B1
• Filed: 10/21/2014
• Issued: 11/17/2015
• Est. Priority Date: 10/21/2014
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Boday, Dylan J., Mauldin, Timothy C.
• Primary Examiner(s): Jones, Jr., Robert
• Application Number:
  US14/519,749
• Time in Patent Office: 392 Days
• US Class Current: 1/1
• CPC Class Codes: C08F 230/02 containing phosphorus
• CPC Class Codes: C08F 269/00 Macromolecular compounds obtained by polymerising monomers on to polymers of heterocyclic oxygen-containing monomers as defined in group C08F24/00
• CPC Class Codes: C08F 283/02 on to polycarbonates or saturated polyesters C08F283/004 takes precedence
• CPC Class Codes: C08G 2261/128 graft
• CPC Class Codes: C08G 63/08 Lactones or lactides
• CPC Class Codes: C08G 63/6922 derived from hydroxy carboxylic acids
• CPC Class Codes: C08G 63/78 Preparation processes
• CPC Class Codes: C08G 63/85 Germanium, tin, lead, arsenic, antimony, bismuth, titanium, zirconium, hafnium, vanadium, niobium, tantalum, or compounds thereof C08G63/823 takes precedence
• CPC Class Codes: C08G 63/912 derived from hydroxycarboxylic acids

Abstract

Flame-retardant polylactic acid-backbone graft and bottlebrush copolymers are synthesized by polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP). In some embodiments of the present invention, the macromonomer is a lactide-functionalized phosphorus-containing polymer that may be synthesized by, for example, polymerizing a phosphorus-containing monomer capable of undergoing radical polymerization (e.g., styrenic, vinylic, acrylic, etc.) using a brominated lactide initiator via atom transfer radical polymerization (ATRP). The brominated lactide initiator may be 3-bromo-3,6-dimethyl-1,4-dioxane-2,5-dione prepared by, for example, reacting lactide with N-bromosuccinimide in the presence of benzoyl peroxide.

Claims

1. A flame-retardant polylactic acid-backbone graft copolymer represented by the following formula:

2. The flame-retardant polylactic acid-backbone graft copolymer as recited in claim 1, wherein the flame-retardant polylactic acid-backbone graft copolymer is represented by the following formula:

3. A flame-retardant polylactic acid-backbone bottlebrush copolymer represented by the following formula:

4. The flame-retardant polylactic acid-backbone bottlebrush copolymer as recited in claim 3, wherein the flame-retardant polylactic acid-backbone bottlebrush copolymer is represented by the following formula:

5. A method for synthesizing a flame-retardant polylactic acid-backbone bottlebrush or graft copolymer, comprising:

polymerizing a lactide functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP), wherein the lactide-functionalized phosphorus-containing macromonomer is a lactide-functionalized phosphorus-containing polymer represented by the following formula;

6. The method as recited in claim 5, wherein the step of polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP) includes polymerizing the lactide-functionalized phosphorus-containing macromonomer alone to produce a flame-retardant polylactic acid-backbone bottlebrush copolymer having the following formula:

7. The method as recited in claim 5, wherein the step of polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP) includes polymerizing the lactide-functionalized phosphorus-containing macromonomer and lactide to produce a flame-retardant polylactic acid-backbone graft copolymer represented by the following formula:

8. The method as recited in claim 5, wherein the lactide-functionalized phosphorus-containing macromonomer is 3-poly(diphenyl(methacryloyloxyethyl)phosphinate)-3,6-dimethyl-1,4-dioxane-2,5-dione.

9. The method as recited in claim 8, wherein the step of polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP) includes polymerizing the 3-poly(diphenyl(methacryloyloxyethyl)phosphinate)-3,6-dimethyl-1,4-dioxane-2,5-dione alone to produce a flame-retardant polylactic acid-backbone bottlebrush copolymer having the following formula:

10. The method as recited in claim 8, wherein the step of polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP) includes polymerizing the 3-poly(diphenyl(methacryloyloxyethyl)phosphinate)-3,6-dimethyl-1,4-dioxane-2,5-dione and lactide to produce a flame-retardant polylactic acid-backbone graft copolymer having the following formula:

11. The method as recited in claim 5, wherein the step of polymerizing a lactide-functionalized phosphorus-containing macromonomer using ring-opening polymerization (ROP) includes the steps of:

preparing a catalyst/initiator solution comprising a catalyst, an initiator and an organic solvent;

adding the catalyst/initiator solution to a reaction vessel;

removing at least some of the organic solvent from the catalyst/initiator solution in the reaction vessel;

adding the lactide-functionalized phosphorus-containing macromonomer to the reaction vessel;

heating the reaction vessel.

12. The method as recited in claim 11, wherein the catalyst is Sn(Oct)₂.

13. The method as recited in claim 12, wherein the initiator is benzyl alcohol.

14. The method as recited in claim 13, wherein the organic solvent is anhydrous toluene.

15. The method as recited in claim 14, wherein the step of heating the reaction vessel includes the step of heating the reaction vessel to at least 120°

C.

16. The method as recited in claim 5, further comprising the step of heating the flame-retardant polylactic acid-backbone bottlebrush or graft copolymer to produce phase separation of polymeric components of the copolymer.

17. The method as recited in claim 6, further comprising the step of heating the flame-retardant polylactic acid-backbone bottlebrush copolymer to produce phase separation of polymeric components of the copolymer.

18. The method as recited in claim 7, further comprising the step of heating the flame-retardant polylactic-acid graft copolymer to produce phase separation of polymeric components of the copolymer.