Synthesis of energetic polyester thermoplastic homopolymers and energetic thermoplastic elastomers formed therefrom

Abstract

Polymerization of α-bromomethyl-α-methyl-β-propiolactone (BMMPL) or α-chloromethyl-α-methyl-β-propiolactone (CMMPL) yielded thermoplastic homopolymers that upon azidation led to a novel energetic thermoplastic polyester: poly(α-azidomethyl-α-methyl-β-propiolactone) (PAMMPL). An energetic copolyether-ester thermoplastic elastomer was prepared by using glycidyl azide polymer, a dihydroxyl terminated energetic polymer, as a macroinitiator for the polymerization of BMMPL or CMMPL. The azidation of the resulting copolyether-ester yielded an energetic thermoplastic elastomer that melted at between 80° C. and 85° C. Polymerization of α-dibromomethyl-β-propiolactone (DBMPL) resulted in a polymer which upon azidation yielded a new energetic polymer that can be used as a binder or into an energetic thermoplastic elastomer synthesis.

We claim:  
     
         1 . An energetic copolyether-ester thermoplastic elastomer of the formula:  
       PAMMPL-DHTEP-PAMMPL  
       where PAMMPL is poly(α-azidomethyl-α-methyl-β-propiolactone) and DHTEP is dihydroxyl terminated energetic polymer.  
     
     
         2 . The energetic copolyether-ester thermoplastic elastomer as set forth in  claim 1 , wherein said elastomer has a melting point of between 80° C. and 85° C.  
     
     
         3 . The energetic copolyether-ester thermoplastic elastomer as set forth in  claim 1 , wherein the dihydroxyl terminated energetic polymer is selected from the group comprising of glycidyl azide polymer (GAP), poly 3-azidomethyl-3-methyloxetane (AMMO), poly 3-nitratomethyl-3-methyloxetane (NIMMO) and polyglycidyl nitrate (GLYN).  
     
     
         4 . The energetic copolyether-ester thermoplastic elastomer as set forth in  claim 3 , wherein the molecular weight of said soft segment is between 500 and 100 000 g/mol and the molecular weight of said hard segment PAMMPL is between 500 and 200 000 g/mol.  
     
     
         5 . The energetic copolyether-ester thermoplastic elastomer as set forth in  claim 4 , wherein the functionality of said soft segment is between 1 and 250.  
     
     
         6 . The energetic copolyether-ester thermoplastic elastomer as set forth in  claim 5 , wherein said functionality is two.  
     
     
         7 . A process for preparing an energetic copolyether-ester thermoplastic elastomer of the formula:  
       PAMMPL-DHTEP-PAMMPL  
       where PAMMPL is poly(α-azidomethyl-α-methyl-β-propiolactone) and DHTEP is dihydroxyl terminated energetic polymer, comprising: 
 providing a dihydroxyl terminated telechelic energetic polymer having a functionality of two;  
 polymerizing BMMPL or CMMPL with said energetic to form a copolymer; and  
 aziding said copolymer.  
 
     
     
         8 . The process as set forth in  claim 7 , wherein said copolymer has a melting point of between 80° C. and 85° C.  
     
     
         9 . The process as set forth in  claim 7 , wherein said dihydroxyl terminated polyether is a soft segment having a molecular weight between 500 and 200,000 g/mol.  
     
     
         10 . The process as set forth in  claim 7 , wherein said PAMMPL is a hard segment having a molecular weight between 500 and 200,00 g/mol.  
     
     
         11 . The process as set forth in  claim 10 , wherein said dihydroxyl terminated polymer is selected from the group comprising: 3-azidomethyl-3-methyoxetane (AMMO), poly 3-nitratomethyl-3 methyloxetane (NIMMO), poly glycidyl nitrate (GLYN) and glycidyl azide polymer (GAP).  
     
     
         12 . An energetic for use as a prepolymer for binder or thermoplastic elastomer synthesis having the formula:  
       
         
           
           
               
               
           
         
       
     
     
         13 . The energetic polyester as set forth in  claim 12 , wherein n is between 3 to 1100.  
     
     
         14 . The energetic polyester as set forth in  claim 13 , wherein said polyester has a molecular weight of 500 g/mol when n is 3.  
     
     
         15 . The energetic polyester as set forth in  claim 13 , wherein said polyester has a molecular weight of 200,000 g/mol when n is 1100.  
     
     
         16 . A process for preparing an energetic polyester as in  claim 3 , comprising the step of polymerizing DCMPL or DBMPL followed by the azidation of the resulting PDCMPL or PDBMPL.