Star-branched polymer with dendrimer core

Abstract

Polyisobutylene (PIB) functionalized with terminal reactive unsaturation is disclosed. Carbocationically polymerized monohalogen-terminated PIB is dehydrohalogenated in a hydrocarbon solvent using an alkoxide of the formula RO-M wherein R is alkyl of at least 5 carbon atoms and M is alkali metal. The PIB obtained has terminal unsaturation which is 100% in the reactive ‘exo’ form which can be converted to succinic anhydride groups (PIB-SA) by the ene reaction with maleic anhydride. The PIB-SA is reactive with amine functional dendrimers to obtain a star-branched polymer having a dendrimer core and PIB branches joined by succinimide linkages. Blends of the star-branched polymer with polypropylene have improved energy absorption properties and controllable moisture/oxygen permeabilities useful in films.

We claim:  
     
         1 . A method for preparing polyisoolefins comprising the steps of: 
 (a) dehydrohalogenating a halogen-terminated polyisoolefin in a hydrocarbon solvent in the presence of alkoxide of the formula RO-M wherein R is alkyl of at least 5 carbon atoms and M is alkali metal; and    (b) recovering polyisolefin having terminal unsaturation.    
     
     
         2 . The method of  claim 1  wherein the dehydrohalogenation step (a) obtains polyisobutylene having a terminal double bond chain end in ‘exo’ form essentially free of ‘endo’ form.  
     
     
         3 . The method of  claim 2  wherein the polyisoolefin is monohalogen-terminated.  
     
     
         4 . The method of  claim 1  wherein the alkoxide is t-pentoxide.  
     
     
         5 . The method of  claim 4  wherein the alkoxide is potassium t-pentoxide.  
     
     
         6 . The method of  claim 1  wherein the isoolefin has from 4 to about 12 carbon atoms.  
     
     
         7 . The method of  claim 6  wherein the isoolefin is isobutylene.  
     
     
         8 . Polyisoolefin having a terminal double bond chain end in ‘exo’ form essentially free of ‘endo’ form.  
     
     
         9 . The polyisoolefin of  claim 8  wherein the polyisoolefin comprises polyisobutylene.  
     
     
         10 . The polyisoolefin of  claim 9  having a molecular weight from 500 to 25 500,000.  
     
     
         11 . The polyisoolefin of  claim 10  having a molecular weight of 500 to 30,000.  
     
     
         12 . The polyisoolefin of  claim 11  having a molecular weight of 500 to 20,000.  
     
     
         13 . The polyisoolefin of  claim 10  having a molecular weight of 20,000 to 500,000.  
     
     
         14 . A method for preparing functionalized polyisoolefins comprising the steps of: 
 (a) dehydrohalogenating a halogen-terminated polyisoolefin in a hydrocarbon solvent in the presence of alkoxide of the formula RO-M wherein R is alkyl of at least 5 carbon atoms and M is alkali metal;    (b) reacting the product from step (a) with maleic anhydride, and    (c) recovering PIB-SA.    
     
     
         15 . A method for preparing a hydrolytically stable star-branched polymeric material having a dendrimer core and polyolefin branches, comprising the steps of: 
 (a) reacting a functionalized polyolefin with a hydrolytically stable dendrimer having primary amine functionality in an outer core, and    (b) recovering star-branched polymeric material.    
     
     
         16 . The star-branched polymeric material prepared by the method of  claim 15 .  
     
     
         17 . A hydrolytically stable star branched polymeric material comprising a hydrolytically stable dendrimer core with branches of polyolefin.  
     
     
         18 . The star branched polymeric material of  claim 17  wherein the polyolefin is a polyisoolefin.  
     
     
         19 . The star-branched material of  claim 18  wherein the polyisoolefin is polyisobutylene.  
     
     
         20 . The star branched polymeric material of  claim 19  wherein at least two polyisobutylene branches have different molecular weights.  
     
     
         21 . The star branched polymeric material of  claim 19  wherein the polyisobutylene branches have a molecular weight between 500 and 20,000.  
     
     
         22 . The star branched polymeric material of  claim 17  comprising a mixture of dendrimer cores of at least 2 generations.  
     
     
         23 . The star branched polymeric material of  claim 19  also comprising branches of polyethylene, polypropylene or ethylene-propylene copolymer.  
     
     
         24 . The star branched polymeric material of  claim 17  wherein the polyolefin is a alpha-olefin polymer.  
     
     
         25 . A composition comprising a blend of polyalpha-olefins with a star-branched polymer comprising a hydrolytically stable dendrimer core with branches of a polyisoolefin, polyalpha-olefins or a mixture of polyisoolefins and polyalpha-olefins.  
     
     
         26 . The composition of  claim 25  wherein polyalpha-olefin is selected from polyethylene, polypropylene, ethylene-propylene copolymers, and polyisobutylene.  
     
     
         27 . The composition of  claim 25  wherein the polyolefin is polypropylene prepared with a metallocene based catalyst.  
     
     
         28 . A film comprising polyolefin blended with a star branched polymeric material comprising a hydrophilic dendrimer core with branches comprising a polyisoolefin.