Preparation of high molecular weight polysuccinimides

Abstract

Described are methods of production of polysuccinimides having molecular weights up to 200,000 daltons and higher. The polysuccinimides of the invention are essentially unbranched and uncrosslinked. They can be modified by crosslinking, ring-opening, and/or other functionalization, if desired, to form gelling materials of superior performance. The high Mw polysuccinimides are also particularly useful as thickening agents, viscosity modifiers, emollients, humectants and in other applications that are known in the art to be serviced most effectively by molecules of higher molecular weight.

1 . A method of solubilizing aspartic acid crystals in an aqueous suspension, to form an aqueous solution of aspartic acid, the method comprising: 
 contacting said crystals in said suspension with a solubilizing agent which does not leave blocking counterions upon drying of the resulting aqueous solution,    wherein said solubilizing agent is selected from (i) a volatile acid, selected from hydrochloric acid, hydrobromic acid, and hydroiodic acid, and (ii) hydrogen ions generated by electrolysis of water in said aqueous suspension.    
   
   
       2 . The method of  claim 1 , wherein said solubilizing agent comprises (ii) hydrogen ions generated by electrolysis of water in said aqueous suspension.  
   
   
       3 . The method of  claim 2 , for use in preparing a polysuccinimide polymer, further comprising the steps of: 
 contacting said aqueous solution with an acidic polymerization catalyst;    drying the solution to give a solid residue; and    heating the residue at a temperature and for an amount of time sufficient to produce a polysuccinimide polymer.    
   
   
       4 . The method of  claim 3 , wherein said acidic polymerization catalyst is selected from the group consisting of phosphoric acid, metaphosphoric acid, diphosphoric acid, polyphosphoric acid, and combinations thereof.  
   
   
       5 . The method of  claim 4 , wherein said catatlyst further comprises phosphorus pentoxide.  
   
   
       6 . The method of  claim 3 , wherein said acidic polymerization catalyst comprises an acidic ion exchange resin.