Method for preparing stereoblock polylactide

Patent metadata

Field	Value
Publication number	US-9914801-B2
Application number	US-201515534274-A
Country	US
Kind code	B2
Filing date	Dec 1, 2015
Priority date	Dec 10, 2014
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

The present invention relates to a method for preparing a stereoblock polylactide, comprising: a step of obtaining a first reaction mixture with a monomer conversion rate of 80 to 95% by adding a catalyst to a D-lactide and growing a PDLA chain; a step of obtaining a second reaction mixture with a monomer conversion rate of 80 to 95% by adding an L-lactide to the first reaction mixture and growing a racemic PDLLA chain at the end of the PDLA chain; and a step of further adding an L-lactide to the second reaction mixture and growing a PLLA chain at the end of the PDLLA chain through a polymerization reaction. The preparation method is capable of providing a more convenient synthesis by skipping a process of removing residual monomers in the middle of the reaction, and also of preventing multi-blocking and oligomerization of polymer chains due to a mixture of chains by gradually adding polymerizable monomers while controlling the monomer conversion rate in a one-port synthesis, thereby reducing chain transfer during the polymerization.

First claim

The invention claimed is:

1. A method for preparing a stereoblock polylactide (sb-PLA), which consists essentially of:
(1) adding a catalyst to D-lactide, performing a polymerization reaction to grow a poly(D-lactide) (PDLA) chain and obtaining a first reaction mixture having a monomer conversion of 80% to 95%;
(2) adding L-lactide to the first reaction mixture, performing a polymerization reaction to grow a racemic poly(D,L-lactide) (PDLLA) chain at a terminal of the PDLA chain and obtaining a second reaction mixture having a total monomer conversion of D-lactide and L-lactide of 80% to 95%; and
(3) adding L-lactide to the second reaction mixture and performing a polymerization reaction to grow a poly(L-lactide) (PLLA) chain at a terminal of the PDLLA chain,

wherein the reactions in steps (1) to (3) are a one-pot reaction where the reactions are continuously performed in one reactor,
wherein the polymerization reaction in step (3) is performed by additionally adding stannous octoate (Sn(Oct) 2 ) to the second reaction mixture as the catalyst.

2. The method of claim 1 , wherein the L-lactide in step (2) is added in an amount of 10 to 30 mol % based on a total mole number of L-lactide added in steps (2) and (3).

3. The method of claim 1 , wherein the catalyst in step (1) is added in an amount of 0.0001 to 0.001 parts by mole based on 1 part by mole of the D-lactide.

4. The method of claim 1 , wherein the catalyst in step (1) is stannous octoate (Sn(Oct) 2 ).

5. The method of claim 1 , wherein the D-lactide and the L-lactide are dried in vacuum for 1 to 10 hours.

6. The method of claim 1 , wherein the catalyst in step (1) is added hi a dissolved state in a solvent, and the solvent is primarily removed prior to the polymerization reaction.

Assignees

• Korea Res Inst Chemical Tech

Inventors

• Lee Jae Chang
• Jegal Jong Geon
• Song Bong Keun

Classifications

• C08L101/00

  Compositions of unspecified macromolecular compounds · CPC title

• C08G63/85

  Germanium, tin, lead, arsenic, antimony, bismuth, titanium, zirconium, hafnium, vanadium, niobium, tantalum, or compounds thereof {(C08G63/823 takes precedence)} · CPC title

• C08G63/91

  Polymers modified by chemical after-treatment · CPC title

• C09D167/04

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C09D167/06 takes precedence) · CPC title

• C08G63/08 Primary

  Lactones or lactides · CPC title