Melt functionalization of polymers

Abstract

A process is provided to graft functional moieties to base polymers by contacting the base polymer with functional group containing diazo compounds. The preferred function group containing diazo is ethyl diazoacetate. The base polymer is a copolymer or polymer having monomer units of alpha olefins, conjugated diolefins, vinyl aromatics, or hydrogenated conjugated diolefins. The process is performed in a melt and results in low levels of scissioning, coupling and degradation.

I claim: 
     
       1. A process comprising the steps of: a) providing a melt of a base polymer, the base polymer comprising polymerized monomers selected from the group consisting of, vinyl aromatics, conjugated diolefins, and hydrogenated conjugated diolefins;   b) contacting the melt of the base polymer with a functional group containing diazo compound thereby producing a functionalized polymer; and   c) recovering the functionalized polymer.   
     
     
       2. The process of claim 1 wherein the diazo compound functional group is an ester group. 
     
     
       3. The process of claim 1 wherein the diazo compound is an alkyl diazoacetate. 
     
     
       4. The process of claim 1 wherein the diazo compound is ethyl diazoacetate. 
     
     
       5. The process of claim 1 wherein the base polymer comprises conjugated diolefin monomer units. 
     
     
       6. The process of claim 1 wherein the polymer is a hydrogenated conjugated diolefin polymer. 
     
     
       7. The process of claim 1 wherein the base polymer is a radial hydrogenated conjugated diolefin polymer. 
     
     
       8. The process of claim 1 wherein the base polymer is a block copolymer comprising at least one block which comprises predominantly conjugated diolefin monomer units and at least one block which comprises predominantly vinyl aromatic monomer units. 
     
     
       9. The process of claim 8 wherein the block copolymer comprises at least two blocks which comprise predominantly vinyl aromatic monomer units. 
     
     
       10. The process of claim 8 wherein the block copolymer is a hydrogenated block copolymer with at least 80 percent of the initial ethylenic unsaturation eliminated by hydrogenation. 
     
     
       11. The process of claim 9 wherein the block copolymer is a hydrogenated block copolymer with at least 98 percent of the initial ethylenic unsaturation eliminated by hydrogenation. 
     
     
       12. The process of claim 1 wherein the base polymer is contacted with between about one and about 200 moles of the diazo compound per mole of base polymer. 
     
     
       13. The process of claim 1 wherein the base polymer is contacted with between about 5 and about 100 moles of the diazo compound per mole of base polymer. 
     
     
       14. The process of claim 1 wherein the monomer is styrene. 
     
     
       15. The process of claim 1 wherein the monomer is butadiene. 
     
     
       16. The process of claim 1 wherein the monomer is isoprene. 
     
     
       17. The process of claim 9 wherein the base polymer is a poly(conjugated diolefin)-polystyrene-poly(conjugated diolefin) block copolymer. 
     
     
       18. The process of claim 17 wherein the block copolymer is selectively hydrogenated block copolymer with more than 90 percent of the ethylenic unsaturation hydrogenated and 95 percent or more of the aromatic unsaturation remaining. 
     
     
       19. The process of claim 1 wherein the base polymer and the diazo compound are contacted in an extruder. 
     
     
       20. The process of claim 2 further comprising the step of hydrolyzing at least a portion of the ester functionality of the functionalized polymer to form acid functionality. 
     
     
       21. The process of claim 20 further comprising the step of neutralizing at least a portion of the hydrolyzed functionality with a metal ion. 
     
     
       22. The process of claim 1 wherein the base polymer is a solid at room temperature. 
     
     
       23. The process of claim 4 wherein the contacting of the melt of the base polymer and the ethyl diazoacetate is accomplished in an extruder. 
     
     
       24. The process of claim 23 wherein the amount of diazoacetate is between about one mole and about 200 moles per mole of base polymer. 
     
     
       25. The process of claim 24 wherein the base polymer is a hydrogenated radial polyisoprene polymer. 
     
     
       26. The process of claim 23 wherein the base polymer is a hydrogenated polybutadiene. 
     
     
       27. The process of claim 23 wherein the base polymer is a polystyrene. 
     
     
       28. The process of claim 23 wherein the base polymer is a selectively hydrogenated block copolymer comprising at least one block which comprises predominantly conjugated diolefin monomer units and at least one block which comprises predominantly vinyl aromatic monomer units and the hydrogenation as eliminated more than 90 percent of the initial ethylenic unsaturation and less than 5 percent of the initial aromatic unsaturation. 
     
     
       29. The process of claim 28 wherein the vinyl aromatic is styrene. 
     
     
       30. The process of claim 29 wherein the conjugated diolefin is isoprene. 
     
     
       31. The process of claim 29 wherein the conjugated diolefin is butadiene. 
     
     
       32. The process of claim 29 wherein the block copolymer comprises at least two blocks which comprise predominantly styrene monomer units. 
     
     
       33. The process of claim 28 wherein the block copolymer and the alkyl diazoacetate are contacted in the extruder at a temperature between about 150° C. and about 260 ° C. for a time period of between about 5 seconds and about ten minutes. 
     
     
       34. The product of the process of claim 1. 
     
     
       35. The product of the process of claim 28.