Multiblock copolymers having improved mechanical properties

Abstract

Replacement of the amorphous peptide domain of a structural biopolymer, such as silk from silkworms or spiders, with a nonpeptide segment while maintaining the β-sheet forming crystalline segments provides synthetic multiblock copolymers having solid-state structures and mechanical properties similar to the naturally occurring structural biopolymer is described herein. Such synthetic multiblock copolymers may be produced as films or fibers.

What is claimed is:  
     
         1 . A composition, comprising the following formula:  
       
         
           
           
               
               
           
         
       
       wherein x is an integer from 2 to 15, and wherein n is an integer from 6 to , and wherein y is an integer from 1 to 5.  
     
     
         2 . A composition, comprising the following formula:  
       
         
           
           
               
               
           
         
       
       wherein x is an integer from 4 to 11, and wherein n is an integer from 6 to , and wherein y is an integer from 1 to 5.  
     
     
         3 . A composition, comprising the following formula:  
       
         
           
           
               
               
           
         
       
       wherein x is an integer from 7 to 14, and wherein n is 13, and wherein y is an integer from 1 to 5.  
     
     
         4 . A composition, comprising the following formula:  
       
         
           
           
               
               
           
         
       
       wherein n is 13 and m is an integer from 1 to 9 and y is an integer from 1 to 5.  
     
     
         5 . A composition, comprising the following formula:  
       
         
           
           
               
               
           
         
       
       wherein n is an integer from 6 to , and wherein y is an integer from 1 to 5, and m is an integer from 1 to 9.  
     
     
         6 . A method for synthesizing multiblock polymers, comprising the following steps: 
 (a) performing an anionic ring-opening polymerization of                           by contacting Ala-NCA with an initiator under conditions suitable for anionic ring-opening, wherein said initiator has the formula                           (a, w-diamino-PEG)     resulting in a triblock intermediate, wherein said intermediate has the formula                           (poly(alanine-b-oxyethylene-b-alanine)     and    (b) contacting said triblock intermediate of (a) with water resulting in 
 (i) a water soluble composition having the formula  
                     
    and 
 (ii) a water insoluble composition having the formula  
                     
   (c) contacting either (i) or (ii) or both of (b) with a chain extender in the presence of DPPA/Et 3 N under conditions suitable for extending polymer (i), (ii) or both resulting in a polymer having the general formula                          
     
     
         7 . The method of  claim 6 , wherein said chain extender in step (c) is poly(ethylene gylcol)bis(carboxymethyl) ether.  
     
     
         8 . The method of  claim 7 , wherein said poly(ethylene gylcol)bis(carboxymethyl) ether is in a LiCl/DMSO medium.  
     
     
         9 . The method of  claim 6 , wherein said “x” is an integer 4 to 11 and “n” is an integer from 6 to , and m is an integer from 1 to 9 in said resultant polymer of step (c).  
     
     
         10 . The method of  claim 9 , wherein said polymer has a molecular weight (Mw) of at least 10,000.  
     
     
         11 . The method of  claim 9 , wherein said polymer has a η inh  of about 0.42 dL/g.  
     
     
         12 . The method of  claim 6 , wherein said “x” is an integer from 7 to 14 and “n” is an integer from 6 to , and m is an integer from 1 to 9 in said resultant polymer of step (c).  
     
     
         13 . The method of  claim 12 , wherein said polymer has a molecular weight (Mw) of at least 10,000.  
     
     
         14 . The method of  claim 12 , wherein said polymer has a η inh  of about 0.31 dL/g.  
     
     
         15 . A method for preparing a composition having the following formula  
       
         
           
           
               
               
           
         
       
       comprising the steps of: 
 (a) coupling a glycine-alanine compound having the formula  
                     
  with Fmoc-GlySer(O'Bu)-OH under conditions suitable for coupling including DCC/HOBt, resulting in a compound having the formula  
                     
 (b) deprotecting the “Fmoc” moiety using piperdine and DMF, and the t-butyl moiety using TFA, resulting in a compound having the following formula  
                     
 (c) treating said resulting compound of (b) with HCl and dioxane yielding a hexa(ethylene glycol)-based peptidic diamine salt having the formula  
                     
 (d) catenating said resultant compound of (c) using poly(ethylene glycol)bis(carboxymethyl) ether in solution having DMSO, DPPA, and Et 3 N resulting in a compound having the following formula  
                     
 
     
     
         16 . The method of  claim 15 , wherein said composition of step (d) has an “n” value ranging from about 1 to about 13.  
     
     
         17 . A multiblock copolymer, comprising the following structure:  
       -[peptide-linker 1 -peptide]-linker 2 -[peptide-linker 3 -peptide]-  
       wherein the peptide blocks are derived from peptide sequences found in native silk biomacromolecules such as the crystalline domains of  N. clavipes  or  B. mori  silks, wherein said linkers  1 ,  2 , and  3  have the general formula (A x B) n  wherein A is either CRR′ or SiRR′, if A is CRR′ then x is an integer from 1 to 4 and R and R′ are independently chosen from H, methyl, ethyl, propyl, and B is a heteroatom such as O, N, or S, wherein if B is N then the substituents on B are chosen from H, methyl, ethyl or propyl groups, if A is CH 2  or (CH 2 ) 2  then n<20, if A is (CH 2 ) 3  or (CH 2 ) 4  then n is greater than or equal to 3; or if A is SiRR′ then x island R and R′ are independently chosen from methyl, ethyl, and vinyl.  
     
     
         18 . A method for preparing a composition having the formula  
       
         
           
           
               
               
           
         
       
       wherein m=1 to 9, y=1 to 5, n=6 to 40  
     
     
         19 . A method for synthesizing multiblock copolymers comprising the following steps: 
 (a) coupling of α,ω-diaminopoly(ethylene glycol) having the formula                           where y =1 to 5     with BOC-(GAGA) m —OH in the presence of HOBT.H 2 O,N,N′-dimethylaminopyridine (DMAP) and dicyclohexylcarbodiimide (DCC) in DMF at 0° C. resulting the compound with the formula                          (b) deprotecting BOC moiety using TFA followed by treatment with HCl (5.6 M) in dioxane with stirring resulting in                           wherein m=1 to 9, y=1 to 5    (c) catenating said resultant compound of (b) using poly(ethylene glycol)bis(carboxymethyl) ether in DMSO solution containing DPPA and triethylamine resulting in a polymer having the following formula:                           wherein m=1 to 9, y=1 to 5, and n=6 to 40    
     
     
         20 . The method of  claim 15  where GSGAGA repeats 2 to 9 times resulting in the compound with the formula  
       
         
           
           
               
               
           
         
       
       wherein m=2 to 9, y=1 to 5, and n=6 to 20.