POLYMERIZATION IN AQUEOUS MEDIA

Abstract: A method for the solution or emulsion polymerization of ethylenically unsaturated monomers, styrene, and other free radical polymerizable monomers in aqueous media in which a cobalt chain transfer agent is used which has both hydrolytic stability and solubility in water and in the organic phase with preferential solubility in the organic phase.

Description: TITLE POLYMERIZATION IN AQUEOUS MEDIA 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 US S 324 879 discloses the use of cobalt(m) complexes to control molecular weights in free radical polymerization. US 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 a) 1,1 -disubstituted ethylenically unsaturated monomer; b) styrene; c) a mixture of a and b; and d) a mixture of at least one of a and b with one or more other free radical polymenzable monomers; said monomer or monomer mixture comprising at least SO percent by weight of monomer selected from at least one of a and b; comprising contacting the following materials: i) water or a single phase water-organic solvent mixture, ii) at least one monomer selected from a to d, iii) a cobalt chelate chain transfer agent, iv) an optional surfactant for emulsion polymerization, v) an optional free radical initiator soluble in the media; wherein the cobalt chelate chain transfer agent has the following properties: vi) hydrolytic stability, and vii) solubility in water and in the organic phase, with preferential solubility in the organic phase. We have discovered that certain types of cob-alt 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. Co(II)(DPG-BF2)2 Y=Z=Ph, L=ligand Co(II)(DMG-BF2)2 Y=Z=Me, L=ligand Co(II)(EMG-BF2)2 Y=Me, Z=Et, L=ligand Co(II)(DEG-BF2)2 Y=Z=Et, L=ligand Co(II)(CHG-BF2)2 Y+Z=-(CH2)4- (cyclohexyl), L=ligand. RCo(III)(DPG-BF2)2 Y=Z=Ph, R= alkyl, =ligand RCo π)(DMG-BF2)2 Y=Z=Me, R= alkyl, L=ligand RCo(III)(EMG-BF2)2 Y=Me, Z=Et, R= alkyl, L=ligand RCo(III)(DEG-BF2)2 Y=Z=Et, R= alkyl, L=ligand RCo(III)(CHG-BF2)2 Y+Z=-(CH2)4- (cyclohexyl), R= alkyl, L=ligand RCo(III)(DMG-BF2)2 Y=Z=Me, R= halogen, L=ligand. The cobalt (III) complexes based on BF2-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. Cobalt(II) complexes [for example, Co(II)(DMG-BF2)2], although effective in emulsion polymerization, have disadvantages when used directly because of their extreme sensitivity to air. It is, therefore, preferable to use cobalt(III) complexes [for example, iPrCo(III)(DMG-BF2)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 cobalt(III) complexes which are reduced to cobalt (II) complexes in a bimolecular process involving reaction with other species in the reaction medium [for example, ClCo(III)(DMG-BF2)2 or MeCo(III)(DEG-BF2)2] Cobalt(III) complexes which are not as readily converted to cobalt (II) complexes[for example MeCo(III)(DMG-BF2)2] are less effective in controlling molecular weight. DETAILS OF THE INVENTION To achieve best control over molecular weight, the ligands (L) are selected to suit the reaction conditions (monomers, cosolvents, surfactant, reaction temperature, etc.). L is selected from Lewis bases including tertiary amines (such as pyridine), water, ether, phosphines, and the like, as will be obvious to one skilled in the art. The use of the cobalt (II) complexes [for example Co(ϋ)(DMG- BF2)2] .gives poor results with hydroxy and acid monomers [for example HEMA or MAA]. The use of the corresponding cobalt(DI) complexes, iPrCo(III)(DMG- BF2)2 or MeCo(Iϋ)(DEG-BF2)2], which are compatible with hydroxy and acid monomers, gives good results. The activity of the cobalt(HI) complexes shows less dependence on surfactant type than is seen with cobalt(II) complexes. Depending on the reaction conditions cobalt(m) complexes are up to 3-20 fold more active than the corresponding cobalt(II) complexes in reducing molecular weight in emulsion polymerization. Although use of a surfactant (iv) may be desirable, such use is not necessary for self-stabilizing systems or systems otherwise stable such as by employment of block or graft copolymer stabilizers. An important factor in controlling activity in emulsion polymerization is the solubility of the complex in aqueous and organic media. The complex should be soluble in both the organic and aqueous phases and the partition coefficient between the aqueous and organic phases should be in favor of the organic phase. Complexes based on diethyl glyoxime [for example, iPrCo(UI)(DEG-BF2)2] are more active than those based on dimethyl glyoxime [for example, iPrCo(III)(DMG-BF2)2]- However, some water solubility is required for the complex to distribute through the reaction mixture. The diphenyl glyoxime complexes [for example, Co(II)(DPG-BF2)2 and MeCo(UI)(DPG-BF2)2] show much reduced activity with respect to corresponding dimethyl glyoxime complexes [for example Co(II)(DMG- BF2)2 and iPrCo(III)(DMG-BF2)2l- Higher complex concentrations are required for molecular weight control with very hydrophobic monomers, for example BMA or styrene. This result is most likely due to the lower solubility of the complex in the organic phase. Use of the term "styrene" herein is intended to include substituted styrenes as well. Another important factor is the stability of the complex to hydrolysis. Incremental addition of the complex during the reaction improves molecular weight control especially in polymerizations of acid monomers (e.g. MAA) or with acidic reaction conditions. For both cobalt(II) and cobalt(m) glyoxime complexes, BF2-bridging improves the hydrolytic stability of the complexes. The use of lower reaction temperatures is also advantageous. Water soluble azo-compounds, for example 4,4'-azobis(cyanovaleric acid), are the preferred initiators for emulsion polymerization and for aqueous solution polymerization. Faster decomposing azo compounds, for example, WAKO V-44 [2,2'-azobis(N,N , -dimethyleneisobutyramidine) dihydrochloride], allow use of lower reaction temperatures (S0-60°C) and are preferred for polymerizations involving methacrylic acid. Organic soluble azo-compounds can also be used for emulsion polymerization in some cases. The preferred monomers for use with this invention are a-methylvinyl and styrenic monomers, mixtures of these monomers and mixtures of these monomers with other unsaturated monomers including acrylic monomers. The preferred a- methylvinyl monomers include: alkyl methacrylates (e.g. MMA, EMA, w-BMA, t- BMA, 2-EHMA, PhMA, etc.) substituted alkyl methacrylates (e.g. HEMA, GMA, etc.), methacrylic acid (e.g. MAA), etc.. In emulsion polymerization, a wide range of surfactants and surfactant concentrations have been used in conjunction with cobalt(m) complexes. Both ionic and non-ionic surfactants may be employed. These surfactants include SDS, ADS, AerosolMA, Teric N40, Teric NX40L, alkanate, AerosolOT/Teric N40 and similar surfactants. These surfactants may be used alone or in combination. CH3(CH 2 )nOSθ3- Na + CH3(CH 2 )ι 1OSO3- Na4 + SDS ADS Aerosol OT Aerosol MA80 Teric 35N5 (Akamte) CH 3 (CH 2 )8— ^ — (C 2 H4θ)40-H CH 3 (CH 2 )τ— i - (C 2 H4θ)40-H Teric N40 Teric NX40L This invention will lead to polymers with a high degree of terminal unsaturation (typically in excess of 90%). Polymers formed with a-methyl vinyl monomers (CH2= (CH3)X) will have the following end-group structure. The products can thus be used as macromonomers in a wide variety of applications. The end group unctionality of the low molecular weight methacrylate ester polymers formed by the processes described can be established quantitatively by NMR spectroscopy or by thermogravimetric analysis. Some typical results are as follows. Within experimental error, there is one unsaturated end group per molecule. Table 1. End Group Functionality in Macromonomers Macromonomer complex a M n b end groups/molecule c MMA iPrCo(III)(DMG-BF2)2 1400 1.04 MMA MeCo(III)(EMG-BF2)2 2100 0.98 MMA MeCo(III)(DEG-BF2)2 2400 0.98 HEMA iPrCo(III)(DMG-BF2)2 810 0.97 a cobalt complex used in macromonomer synthesis, b GPC number average molecular weight. c unsaturated chain end as estimated by NMR. Some of general advantages of polymerisation in emulsion and aqueous solution polymerisation is organic solutions have been delineated above. A further unexpected and important advantage of forming macromonomers in aqueous or part-aqueous media is that the products have substantially less color than those formed in organic media. Color is extremely important in many applications, for example, clear and light colored coatings and other materials. Illustrative of the invention are the following examples showing the dependence of molecular weight on the type of complex, surfactant and comonomers employed; application to copolymer synthesis; and aqueous solution polymerisation of methacrylic acid and 2-hydroxyethyl methacrylate. EXAMPLES 1-10 Emulsion polymerization with cobalt (II) complexes Initial Charge: Solution 1: Water 733 g Surfactant solution (30% w/v) 10.14 g 4,4'-azobis(cyanovaleric acid) 1.32 g Solution 2: iPrCo(m)(DMG-BF2)2 0.0176 g MMA 35.2 g Solution 3: MMA 317 g Solution 4: Water 90 g Surfactant solution (30% w/v) 10.98 g Solution 1 was degassed over 30 minutes and heated to 80°C when solution 2 and 10% of solution 4 was added in one shot. Solution 3 and the remaining solution 4 were then added over 90 min. The reaction temperature was then held for a further 90 min. The results of this and similar experiments are summarized in Table 2. Table 2. EfTect of Complex, , Surfactant and Initiator, Cobalt (II) Complexes Cone Particle Example Complex (ppm) Initiator M n Mw Mn Surfactant size none 0 0.27% V5010 177100 2.1 1.4% ADS 99 1 Co(II)DPG 50 0.27% V5010 151000 2.2 1.4% ADS 87 2 Co(π)DMG 5 0.27% V5010 192600 2.1 1.4% ADS 93 3 50 0.27% V5010 171400 1.8 1.4% ADS 95 4 Co(II)DPG 50 0.27%V5010 179000 2.3 1.4% SDS 80 5 CodDDMG 50 0.27% V5010 20000 1.8 1.4% SDS 281 6 100 0.27% V5010 16100 2.5 1.4% SDS 407 none 0 0.1% V5010 585600 2.3 1.4% SDS 115 7 Co(II)DMG 50 0.1% V5010 70600 2.4 1.4% SDS 322 none 0 0.1% V5010 452500 2.1 6% SDS 68 8 Co(II)DMG 50 0.1% V5010 48200 2.1 6% SDS 206 9 Co(II)DMG 100 0.1% V5010 38400 2.6 6% SDS 276 none 0 0.1% -APS 132152 3.3 1.4% SDS 148 10 CodDDMG 50 0.1% APS 64768 1.7 1.4% SDS 118 a , initiators: APS ammonium persulphate; V5010 4,4'-azobis(cyanovaleric acid) EXAMPLES 11-33 Emulsion polymerization with cobalt (III) complexes (with surfactant feed) Solution 1 : Water 75 g Surfactant solution (10% w/v) 3 g 4,4'-azobis(cyanovaleric acid) 140 mg Solution 2: Surfactant solution (10% w/v) i g iPrCo(HI)(DMG-BF2)2 1.96 mg MMA 3 5 g Solution 3: MMA 31.2 g Solution 4: Surfactant solution (10% w/v) 8 g Solution 1 was degassed over 20 minutes and heated to 80°C when solution 2 was added in one shot. The feeds (solution 3 and 4) were commenced and added over 90 min. The reaction temperature was then increased to 85°C and heating and stirring continued for a further 90 min. Results of this and similar experiments are summarized in Tables 3-5. Table 3. EfTect of Complex on Emulsion Polymerisation of MMA a cone Example Complex M Δ, . M /M n Conv coagulum none 0 181000 2.5 100 11 Co(TI)(DMG-BF 2 )2 14 29900 2.4 95 5 12 iPrCo(iπ)(DMG-BF 2 ) 2 17 10000 2.2 100 4 13 2-octyl Co(III)(D G-BF 2 ) 2 18 6200 1.7 34 4 14 iPrCo(III)(CHG-BF 2 ) 2 16 18600 2.1 100 3 15 MeCoαiI)(EMG-BF 2 )2 16 6200 1.9 91 4 16 MeCo(πi)(DEG-BF2)2 16 3200 1.6 93 6 17 Co(ID(DPG-BF 2 ) 2 22 119200 2.5 72 1 18 EtCo(III)(DPG-BF 7 ) 7 24 30600 1.9 92 5 1% (w/v) SDS surfactant Table 4. EfTect of Surfactant on Emulsion Polymerization of MMA a % % Example Surfactant wt% b M n Miy/ n Conv» d coagulum 19 SDS 0.1 14200 2.5 100 11 20 SDS 0.5 10600 3.2 92 4. 21 SDS 1.0 10000 2.1 100 4 22 SDS 3.0 8100 1.9 100 14 23 ADS 1.0 16000 2.2 62 2 24 Aerosol MA80 1.0 13100 2.0 80 13 25 SDS/Teric N40 0.1 11200 2.9 100 6 26 SDS Teric NX40L 0.1 12300 2.5 100 17 27 alkanate 0.1 21000 2.0 88 13 28 AerosolOT/Teric N40 0.1 12700 2.0 92 16 29 AerosolOT/Teric NX40 0.1 29800 2.2 91 12 a iPrCo(III)(DMG-BF2)2 concentration 19 ppm. b Surfactant level Table 5. Effect of Comonomers on Emulsion Polymerization of MMA none 3 - 1 100000000 - - 1 10000 30 HEMAa< c 88::11 1 100660000 2 2..00 7 755 31 HEMA D ' C 88:: 11 1 199000000 3 3..00 32 MAA b 88::11 1 177660000 2 2..66 9 900 33 n-BMA:2-EHMA:MAA:HEMA:MAm a dd 8 8550000 2 2 22 9 900 a r/o (w/v) SDS surfactant, iPrCo(III)(DMG-BF2)2 concentration 17 ppm b 1% (w/v) SDS surfactant, iPrCo(III)(CHG-BF2)2 concentration 17 ppm c control (no complex) gave Mn 119500, M w M n 6.9. d ratio of monomers was 10 : 1 : 1 : 20 : 1 EXAMPLES 34-49 Emulsion polymerisation recipe (no surfactant feed) Initial Charge: Solution 1: Water 75 g SDS solution (10% w/v) 3 g 4,4'-azobis(cyanovaleric acid) 140 mg Solution 2: iPrCo(m)(DMG-BF2)2 2 mg MMA 3.5 g Feed: MMA 31.7 g Water was degassed over 20 minutes and heated to 80°C when solution 2 was added in one shot. The MMA feed was then added over 90 min. The reaction temperature was then increased to 85°C and heating and stirring continued for a further 90 min. Results are summarized in Tables 6 and 7. Table 6. Emulsion Polymerisations of MMA - dialkylglyoxime based complexes 8 Example Complex cone, ppm M„ Mw/Mn % Conv. 34 iPrCoαiI)(DMG-BF 2 )2 19 13400 3.68 100 35 190 1400 3.03 83 36 MeCo(III)(EMG-BF 2 ) 2 19 4300 1.87 100 37 45b 2100 1.69 94 38 MeCo(III)(DEG-BF 2 )2 19 2900 1.58 69 39 57 920 1.65 51 40 49b 730 1.70 82 41 48° 900 1.78 90 42 MeCo(III)(DMG-BF 2 ) 2 46° 13700 2.65 100 43 14700 2.55 100 a 1% (w/v) SDS surfactant. b 30% of total complex added in MMA feed. Table 7. Emulsion Polymerisation of Other Monomers 3 Example Monomer Complex cone, ppm M„ Mwt n % Conv 44 n-BMA iPrCo(IID(DMG-BF 2 ) 2 48 9800 1.8 98 45 n-BMA MeCo(m)(DEG-BF2)2 48 5200 2.5 97 46 n-BMA MeCo(III)(EMG-BF 2 ) 2 48 9400 2.5 100 47 t-BMA MeCo(ra (DEG-BF2)2 43 3700 2.0 100 48 PhMA MeCc m)(DEG-BF2)2 43 18000 2.3 100 49 GMA iPrCo(III)(DMG-BF2)2 109 3500 1.8 90 30% of complex added with monomer feed, 1% (w/v) SDS surfactant. EXAMPLES 50-51 Preparation of Styrene Initial Charge: distilled water 75.03 g Initiator (azobiscyanopentanoic acid) 0.1440 g Surfactant (10% aq. soln of sodium dodecyl sulfate) 3.14 g Styrene 3.59 g MeCo(III)(DEG-BF2)2 0.0031 g Acetone 0.5 mL (Complex was dissolved in acetone) Feed 1 (180 min @ 0.200 mlJmin) Styrene 33.01 g MeCo(III)(DEG-BF2)2 0.0121 g Acetone 1.0 mL (Complex was dissolved in acetone) Feed 2 (90 min @ 0.089 mlJmin) Initiator (azobiscyanopentanoic acid) 0.0690 g Surfactant ( 10% aq. sob of SDS) 8.12 g (This solution was prepared by gently warming to 60°C) Water was charged to a 5 neck, 250 mL reactor fitted with stirrer (400 rpm), condenser and thermocouple under a blanket of nitrogen. Initiator and surfactant were added to the reactor as single shots and heated to 80°C. When the reactor reached 80°C, the cobalt and styrene were added as single shots and Feed 1 commenced over 180 min. Some of the cobalt precipitated out of the monomer feed. Feed 2 (containing initiator/surfactant) was started 30 min after the start of polymerisation. The reactor was maintained at 80°C for 90 min after the completion of the monomer feed, then cooled. The reactor was sampled at 30 min intervals to monitor molecular weight and conversion . Yield: 105.3 g stable white latex + small amount (< 0.2 g) yellow coagulum Table 8. Emulsion Polymerization of Styrene Example Monomer Complex cone, M n w Mn % Coπv ppm Styrene none (control) 130500 2.7 93 50 Styrene MeCo(ffl (DEG-BF2)2 127 44000 3.2 94 51 Stvrene MeCofIII)(DMG-BF 7 ) 2 127 48000 4.8 97 EXAMPLE 52 Preparation of 60:40 MAA/MMA Macromonomer Initial Charge: Deionised Water 150 g Solution 1 Antrox CA897 0.6 g Antrox CO436 0.3 g Initiator WAKO V-44 0 4 g iPrCo(iπ)(DMG-BF2)2 8 mg MMA 4 g Solution 2: iPrCo(UI)(DMG-BF2)2 16 mg MMA 44.8 g Solution 3: MAA 28.0 g Water (150 mL) was degassed for 20 minutes with a nitrogen purge and heated to 58°C. Solution 1 was added in one shot. The feeds (solutions 2 and 3) were then added over 60 minutes. That rate of feed two was such that 5g was added over the first 20 min, lOg over the second 20 min, and the remainder over the third 20 min. The reaction was held at 58°C for 30 minutes then heated to 65°C for 1 hour and cooled. Conversion >95%, GPC molecular weight M n 920, M w M n 1 6. EXAMPLES 53-58 Preparation of BMA/HEMA/MAA/MMA copolymer Initial Charge Water 75 g SDS (10% solution) 3 g 4,4'-azobis(cyanovaleric acid) 141 mg Solution 1: MeCo(m)(EMG-BF2)2 3.00 mg MMA 0.098 g MAA 0.62 g BMA 2.13 g HEMA 1 48 g Solution 2: MMA 0.562 g BMA 12.02 g MeCo(III)(EMG-BF2)2 2.00 mg Solution 3 : MAA 7.76 g HEMA 8.45 g The initial charge was degassed for 30 minutes with a nitrogen purge and heated to 80°C with a preheated water bath. Solution 1 was added in one shot. Solutions 2 and 3 were then added simultaneously over 90 min. On completion of the feeds, the temperature was increased to 85°C and held for 90 min The results of this and similar experiments are summarized in Table 9. Table 9. Emulsion Copolymerization of MMA/MAA/BMA/HEMA Example Complex ppm Mn M w Mw/ n Conv. 53 iPrCo(III)(DMG-BF 2 ) 2 130 3 5900 17600 2.97 100 % 54 iPrCo(III)(DMG-BF 2 ) 2 80 b 2900 3700 1.29 100 % 55 MeCo(III)(EMG-BF 2 ) 2 110° 4000 11400 2.85 96 % 56 MeCo(III)(EMG-BF 2 ) 2 50 3 4900 12600 2.53 100 % 57 MeCo(iπ)(DEG-BF 2 ) 2 lll b 830 1500 1.74 96 % 58 MeCo(III)(DEG-BF2) 80 3 2300 3200 1.44 100 % a All complex in solution 1. b 40% of total complex added with Feed 1. EXAMPLES 59-62 Preparation of GMA-MMA macromonomer Initial charge: distilled water 75 g SLS (3% solution) 5 g Solution 1 : 4,4'-azobis(cyanovaleric acid) 140 mg GMA 2.6 g MMA 1.0 g MeCo(πi)(DEG-BF2)2 8.9 mg Feed: GMA 18 g MMA 13.5 g MeCo(m)(DEG-BF2)2 7.9 mg The water- SLS mixture was vacuum degassed for 30 minutes and placed 5- neck, reactor fitted with a stirrer, condenser and a thermocouple under a blanket of nitrogen and heated to 80°C. Solution 1 was then added and the Feed commenced immediately and added over 90 minutes. The reactor was maintained at 80°C for a further 90 minutes. Conversion based on % solids was >90%. Table 10. Emulsion Copolymerization of MMA and GMA Example Complex ppm Mn M w /M n 59 iPrCo(iπ)(DMG-BF2)2 a 213 790 2.04 60 iPrCo(IH)(DMG-BF 2 )2 a 135 2900 1.51 61 iPrCo(IID(DMG-BF 2 ) 2 100 3620 2.13 62 MeCo(iπ)(DEG-BF 2 ) 2 146 1460 1.55 a Latex unstable EXAMPLE 63 Aqueous Solution polymerization of MAA Initial Charge: distilled water 150 g Initiator (WAKO VA-044) 0.3 g water 2 mL iPrCo(m)(DMG-BF2)2 13 mg acetone 2 mL Feed: methacrylic acid 74 g iPrCo(ILI)(DMG-BF2)2 7.5 mg Water (150 mL) was charged to a 5 neck, 500 mL reactor fitted with stirrer (300 rpm), condenser and thermocouple under a blanket of nitrogen and heated to 55°C. Initiator (0.3 g dissolved in 2 mL water) and iPrCo(III)(DMG-BF2)2 (13 mg dissolved in 2 mL acetone) were added to the reactor as single shots. The feed of MAA containing the remaining iPrCo(HI)(DMG-BF2)2) was commenced immediately (1.23 mlJmin over 60 min). The reactor was maintained at 55°C for 30 min after the completion of the feed, then cooled. The methacrylic acid macromonomer was isolated by evaporation of the water. Conversion: approx. 90%, NMR analysis indicates number average molecular weight of about 1000. EXAMPLES 64-72 Aqueous Solution polymerization of HEMA The color of the product is dramatically lighter than similar macromonomers prepared in organic solvents (e.g., isopropanol). Complex activity is also higher. Initial Charge: distilled water 52 g methanol 23 g Solution 1 : 4,4'-azobis(cyanovaleric acid) 140 g iPrCo(IH)(DMG-BF2)2 10 mg in 3.5 g HEMA Solution 2: HEMA 31.7 g iPrCo(m)(DMG-BF2)2 mg The water-methanol mixture was charged to a 5 neck, 500 mL reactor fitted with stirrer (300 rpm), condenser and thermocouple under a blanket of nitrogen and heated to 80°C. The initiator (0.14 g dissolved in 3.5 mL HEMA) and iPrCo(πi)(DMG-BF2)2 were added to the reactor as a single shot. The feed of HEMA containing the remaining iPrCo(IU)(DMG-BF2)2) was commenced immediatelyand added over 90 min. The reactor was maintained at 80°C for 150 min after the completion of the feed. Further aliquots of the initiator (70 mg) were added at 1 hourly intervals. The results of these experiments are sumarized in Table 11. Table 11. Aqueous Solution Polymerization of HEMA % % Example Complex solids ppm solvent Mn a Conv Colour 64 MeCo(m)(DEG-BF 2 ) 2 30 56 a water 3180 93 cloudy yellow 65 iPrCoOH)(DMG-BF ) 2 30 56 a water 1470 87 pale yellow 66 iPrCoOII (DMG-BF2) 2 30 171 a water 990 68 paJe yellow 67 iPrCo(IID(DMG-BF 2 ) 2 40 343 water 530 72 pale orange 68 iPrCo(IID(DMG-BF 2 ) 50 400 water 490 72 pale orange 69 iPiCo(m)(DMG-BF 2 ) 2 30 162 isopropanol 420 37 dark brown 70 iaPrCo(III)(DMG-BF 2 )2 30 160 70:30 water - 590 30 brown isopropanol 71 iPτCθ(πi)(DMG-BF2)2 30 105 70:30 water - 1610 98 pale yellow methanol 72 iPτCo(III)(DMG-BF2)2 30 162 70:30 water - 810 68 pale yellow methanol a number average molecular weight estimated by NMR determination of the unsaturate end groups GENERAL PROCEDURE FOR PREPARATION OF COBALT(III) CATALYSTS Preparation of [bis[m-[(2,3-hexanedione dioximato)(2-)-O:O']] tetrafluorodiborato (2-) -N.N'.N",^'] (methyl) (aqua) cobalt Cobalt(Hl) complexes of the invention and all such complexes useful in the disclosed process are made by appropriate compound substitutions in the procedure described in Paragraph A hereafter. The same is true for Cobalt(H) complexes of the invention and of utility generally in the disclosed process. One skilled in the art will have no difficulty, given the disclosure that has been provided, in making all such complexes and in pairing the appropriate Lewis base(s) and cobalt-containing moieties to obtain the claimed cobalt complexes and to obtain the fruits of the claimed process. A. Preparation of Methyl pyridinato-Co(ILT)-DEG Methanol 50 mL 3,4-hexanedione dioxime 3.0 g C0CI2 6H2O 2.0171 g Solution 1: Sodium hydroxide 0.819 g Water 0.819 g Pyridine 0 670 mL Solution 2: Sodium hydroxide 0.532 g Water 0.532 g Sodium borohydride 0.365 g Methyl bromide 0.590 mL The methanol was degassed under nitrogen for 20 minutes at room temperature and the C0G2-6H2O and the 3,4-hexanedione dioxime were added. After ten minutes the Solution 1 was added, followed by slow addition of pyridine. The reaction mixture was cooled to -20°C and stirring under nitrogen was continued for 20 minutes. The second sodium hydroxide solution and the sodium borohydride were added slowly. Methyl bromide was added dropwise over 20 minutes and the reaction mixture was allowed to reach room temperature. Half of the solvent was removed by evaporation and 40 mL of cold water was added. The compound was filtered and washed with a pyridine-water (5%) solution, and dried overP2θ5. B: Preparation of Methyl pyridinato-Co(IH DEG BF2 Bridged. Methyl pyridinato-Co(iπ)-DEG 3.551 g BF3Et2O 9.217 g Ether 5 mL The boron triethyletherate and ether were cooled under nitrogen at -20°C for 40 minutes. The methyl pyridinato-Co(III)-DEG was added over 20 minutes. The reaction was allowed to reach room temperature, then the compound was isolated by filtration and washed with ether. C: Preparation of Methyl aqua-Co(m)-DEG BF2 Bridged. Methyl pyridinato-Co(m)-DEG BF2 bridged 3.178 g Water 30 mL The water was degassed under nitrogen at 30°C for 10 minutes. The methyl pyridinato-Co(III)-DEG BF2 Bridged complex was added and the solution held at 30°C for 40 minutes. The solution was allowed to reach room temperature and the compound was isolated by filtration, and washed with water PROCEDURE FOR PREPaARING COBALT(II) CATALYSTS The Co(II) cobaloximes are prepared as are the Co(III) materials described above without the reaction of the intermediate with alkyl bromide, by reacting the appropriate dioxime with cobaltous chloride and bridging the reaction product with BF3 etherate.

Claims: _________ 1. A method for the solution or emulsion polymerization in aqueous media of at least one monomer selected from the group a) 1,1-disubstituted ethylenically unsaturated monomer; b) styrene; c) a mixture of a and b; and d) a mixture of at least one of a and b with one or more other free radical polymerizable monomers; said monomer or monomer mixture comprising at least 50 percent by weight of monomer selected from at least one of a and b; comprising contacting the following materials: i) water or a single phase water-organic solvent mixture, ii) at least one monomer selected from a to d, iii) a cobalt chelate chain transfer agent, iv) an optional surfactant for emulsion polymerization, v) an optional free radical initiator soluble in the media; wherein the cobalt chelate chain transfer agent has the following properties: vi) hydrolytic stability, and vii) solubility in water and in the organic phase, with preferential solubility in the organic phase. 2. A method according to Claim 1 wherein the cobalt chelate chain transfer agent is selected from at least one square planar cobalt(II) or cobalt(lll) chelate. 3. A method according to Claim 2 wherein the cobalt chelate chain transfer agent is selected from at least one member of the group Co(II)(DPG-BF2)2 Y=Z=Ph, L=ligand Co(π)(DMG-BF2)2 Y=Z=Me, L=ligand Co(H)(EMG-BF2)2 Y=Me, Z=Et, L=ligand Co(II)(DEG-BF2)2 Y=Z=Et, L=ligand and Co(π)(CHG-BF2)2 Y+Z=-(CH2)4-, L=ligand. 4. A method according to Claim 3 wherein the cobalt chelate chain transfer agent is Co(ϋ) (dimethyl glyoxime-BF2)2- 5. A method according to Claim 3 wherein the cobalt chelate chain transfer agent is Co(II) (diethyl glyoxime-BF2)2- 6. A method according to Claim 2 wherein the cobalt chelate chain transfer agent is selected from at least one member of the group RCo( )(DPG-BF2)2 Y=Z=Ph, R= alkyl, L=ligand RCo(m)(DMG-BF2)2 Y=Z=Me, R= alkyl, L=ligand RCo(m)(EMG-BF2)2 Y=Me, Z=Et, R= alkyl. L=ligand RCo(HI)(DEG-BF2)2 Y=Z=Et, R= alkyl. L=ligand RCo(III)(CHG-BF2)2 Y+Z=-(CH2)4- , R= alkyl- L=lιgand and RCo(m)(DMG-BF2)2 Y=Z=Me, R= halogen, L=ligand 7. A method according to Claim 6 wherein the cobalt chelate chain transfer agent is alkylCo(III) (dimethyl glyoxime-BF2)2 8. A method according to Claim 6 wherein the cobalt chelate chain transfer agent is alkylCo(III) (diethyl glyoxime-BF2)2- 9. A method according to Claim 1 wherein the polymer formed is a macromonomer. 10. A cobalt chelate chain transfer agent selected from the group: composing. RCo(m)(EMG-BF2)2 Y=Me, Z=Et, R= alkyl, L=ligand; RCo(πi)(DEG-BF2)2 Y=Z=Et, R= alkyl, L=ligand; and RCo(ffl)(CHG-BF2)2 Y+Z=-(CH2)4- , R= alkyl, L=ligand.

Inventors: FRYD MICHAEL, KRSTINA JULIA, MOAD CATHERINE LOUISE, MOAD GRAEME, RIZZARDO EZIO, THANG SAN HOA, FRYD, MICHAEL, KRSTINA, JULIA, MOAD, CATHERINE, LOUISE, MOAD, GRAEME, RIZZARDO, EZIO, THANG, SAN, HOA
Applicants: COMMW SCIENT IND RES ORG, DU PONT, FRYD MICHAEL, KRSTINA JULIA, MOAD CATHERINE LOUISE, MOAD GRAEME, RIZZARDO EZIO, THANG SAN HOA, COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH OR, E.I. DU PONT DE NEMOURS AND COMPANY, FRYD, MICHAEL, KRSTINA, JULIA, MOAD, CATHERINE, LOUISE, MOAD, GRAEME, RIZZARDO, EZIO, THANG, SAN, HOA
Application year: 1995
Main classification: C08F2
IPC codes: C08F2, C08F12, C08F20, C08F290, C08F293