Polymerization in aqueous media

Details Polymerization in aqueous media Polymerization in aqueous media

1997-05-05

1998-05-26

Schofer, Joseph L.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

526 80, 526346, 526 82, 556140, C08F 442, C08F 210, C08F 1208, C07F 1506

Patent

active

057566054

DESCRIPTION:

BRIEF SUMMARY
FIELD OF INVENTION

This invention relates to free-radical polymerization in emulsion or in aqueous solution to produce polymers with defined molecular weight and end group structures and to certain cobalt complexes employed in the polymerization process.


BACKGROUND ART

U.S. Pat. No. 5,324,879 discloses the use of cobalt(III) complexes to control molecular weights in free radical polymerization. U.S. Pat. No. 4,694,054 discloses the use of certain Co(II) complexes in emulsion polymerization.


SUMMARY OF THE INVENTION

This invention concerns a method for the solution or emulsion polymerization in aqueous media of at least one monomer selected from the group
b) styrene; polymerizable monomers; monomer selected from at least one of a and b; comprising contacting the following materials: properties: solubility in the organic phase.
We have discovered that certain types of cobalt complexes are most effective in controlling the molecular weights in emulsion polymerization or in aqueous solution. These complexes act as efficient catalytic chain transfer agents and produce polymers with unsaturated chain ends. Either cobalt (II) complexes or cobalt (III) complexes can be utilized in the present invention. The reaction conditions are extremely important in determining the success of the experiment and must be chosen with regard to the complex used.
This invention provides a process whereby free radical polymerization can be readily carried out in aqueous or part aqueous media to produce macromonomers. Such macromonomers are oligomeric or homo- or copolymers containing unsaturation at a terminus. The macromonomers are of low color and have a high degree of terminal unsaturation. The process of the invention utilizes free radical polymerization in the presence of a metal complex which gives catalytic chain transfer and which in addition has ligands necessary to convey the necessary hydrolytic stability and solubility parameters. Complexes suitable for emulsion polymerization have solubility in both the organic and aqueous phases and partition in favor of the organic phase. Complexes suitable for aqueous solution polymerisation are soluble in water-monomer or water-monomer-cosolvent mixtures.
A list of preferred complexes is shown below. It will be obvious to those skilled in the art that any metal complex which gives catalytic chain transfer and which in addition has ligands necessary to convey the necessary hydrolytic stability and solubility parameters may be used in the present invention. Preferred complexes are those selected from square planar cobalt(II) and cobalt(III) chelates.


______________________________________ ##STR1## Co(II)(DPGBF.sub.2).sub.2 Y = Z = Ph, L = ligand CO(II)(DMGBF.sub.2).sub.2 Y = Z = Me, L = ligand CO(II)(EMGBF.sub.2).sub.2 Y = Me, Z = Et, L = ligand CO(II)(DEGBF.sub.2).sub.2 Y = Z = Et, L = ligand CO(II)(CHGBF.sub.2).sub.2 Y + Z = (CH.sub.2).sub.4 -(cyclohexyl), L = ligand. ##STR2## RCo(III)(DPGBF.sub.2).sub.2 Y = Z = Ph, R = alkyl, L = ligand RCo(III)(DMGBF.sub.2).sub.2 Y = Z = Me, R = alkyl, L = ligand RCo(III)(EMGBF.sub.2).sub.2 Y = Me, Z = Et, R = alkyl, L = ligand RCo(III)(DEGBF.sub.2).sub.2 Y = Z = Et, R = alkyl, L = ligand RCo(III)(CHGBF.sub.2).sub.2 Y + Z = (CH.sub.2).sub.4 -(cyclohexyl), R = alkyl, L = ligand RCo(III)(DMGBF.sub.2).sub.2 Y = Z = Me, R = halogen, L = ligand. ______________________________________
The cobalt (III) complexes based on BF.sub.2 -bridged 3,4-hexandione dioxime, 2,3-pentandione dioxime and 1,2-cyclohexanedione dioxime ligands are designed to give improved stability and/or solubility parameters. effective in emulsion polymerization, have disadvantages when used directly because of their extreme sensitivity to air. It is, therefore, iPrCo(III)(DMG-BF.sub.2).sub.2 ! which generate the active cobalt(II) species in situ under the reaction conditions. In the case of most alkyl cobalt (III) complexes this involves homolytic scission of the cobalt-R bond.
Other complexes that can be used include coba

REFERENCES:
patent: 4680352 (1987-07-01), Janowicz et al.

Affiliated with

Also associated with

Rating

Polymerization in aqueous media does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Polymerization in aqueous media, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymerization in aqueous media will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1961238