Method of controlling polymer molecular weight and structure

Abstract

This invention concerns the preparation of polymers of low polydispersity and/or controlled molecular weight and architecture employing living free radical polymerization initiated by an alkoxyamine initiator or nitroxide plus, optionally, a free radical initiator; the polymer produced thereby; selected nitroxide and alkoxyamine initiators; and a process for making the initiators; the polymeric products being useful in protective coatings.

1 . A polymer of the formula:  
       
         
           
           
               
               
           
         
       
       wherein: 
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring;  
 X is selected from the group consisting of hydrogen, C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; and X and R 3  can form a 5-8 membered ring;  
 M is one or more monomer units selected from the group consisting of styrene, substituted styrene, alkyl acrylate, alkyl methacrylate, substituted alkyl acrylate, substituted alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, isoprene and butadiene;  
 n is an integer greater than 1;  
 Y is a residue derived from a species that initiates free radical polymerization or is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 1  to C 18  alkoxy, substituted C 1  to C 18  alkoxy, C 6  to C 18  aryl, C 6  to C 18  substituted aryl, C 6  to C 18  aroyloxy, C 6  to C 18  substituted aroyloxy; and  
 all substituents are independently selected from the group that consists of epoxy, hydroxy, C 1  to C 18  alkoxy, acyl, acyloxy, alkoxycarbonyl, aryloxycarbonyl, cyano, silyl, halo, and C 1  to C 18  dialkylamino.  
 
     
     
         2 . A process for preparing the polymers of  claim 1  comprising contacting reactant (i) with one or both of reactants (ii) and (iii) wherein: 
 (i) is at least one monomer M;  
 (ii) is at least one nitroxide of Formula (1)  
                     
 and a source of free radicals Y.; and  
 (iii) is at least one alkoxyamine selected from the formula  
                     
 wherein:  
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 8  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring;  
 X is selected from the group consisting of hydrogen, C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; and X and R 3  can form a 5-8 membered ring;  
 M is one or more monomer units selected from the group consisting of styrene, substituted styrene, alkyl acrylate, alkyl methacrylate, substituted alkyl acrylate, substituted alkyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, isoprene and butadiene;  
 Y is a residue derived from a species that initiates free radical polymerization or is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 1  to C 18  alkoxy, substituted C 1  to C 18  alkoxy, C 6  to C 18  aryl, C 6  to C 18  substituted aryl, C 6  to C 18  aroyloxy, C 6  to C 18  substituted aroyloxy, (C 1  to C 18  alkoxy)carbonyloxy, (C 6  to C 18  aryloxy)carbonyloxy, and sulfate radical anions;  
 all substituents are independently selected from the group that consists of epoxy, hydroxy, C 1  to C 18  alkoxy, acyl, acyloxy, alkoxycarbonyl, aryloxycarbonyl, cyano, silyl, halo, and C 1  to C 18  dialkylamino;  
 Z is a group having at least one carbon atom and is such that the carbon centered radical Z. is capable of initiating free radical polymerization of the monomer (M); and 
 Y and the reaction conditions are selected so that the Y(M) n -O moiety in the compounds of Formula (2) formed from reactants (i) and (ii) undergo facile homolysis;  
 Z and the reaction conditions are selected so that the Z-O moiety and the Z(M) n -O moiety formed by reacting (i) and (iii) undergo facile homolysis; and  
 n is an integer of 1 or greater.  
 
 
     
     
         3 . Nitroxides of the formula  
       
         
           
           
               
               
           
         
       
       wherein: 
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring; and  
 X is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; and X and R 3  can form a 5-8 membered ring; with the proviso that at least one of R, R 1 , R 2 , R 3  and X is not methyl.  
 
     
     
         4 . A nitroxide of  claim 3  selected from the group:  
       
         
           
           
               
               
           
         
       
       where X is selected from the group consisting of alkyl, optionally substituted alkyl, benzyl; and  
       
         
           
           
               
               
           
         
       
       where X is alkyl of C 1  to C 18 .  
     
     
         5 . An alkoxyamine of the formula  
       
         
           
           
               
               
           
         
       
       wherein: 
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring;  
 X is selected from the group consisting of hydrogen, C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; X and R 3  can form a 5-8 membered ring; and  
 Z is a group having at least one carbon atom and is such that the carbon centered radical Z. is capable of initiating free radical polymerization of the monomer (M).  
 
     
     
         6 . An alkoxyamine of  claim 5  wherein Z is selected from the group consisting essentially of —C(Me) 2 Ph, —C(Me) 2 CN, —C(Me)(CN)CH 2 CH(Me) 2 , —C(Me)(CN)(substituted alkyl), —C(Me) 2 CO 2 Alkyl, —C(Me) 2 CO 2 H, —C(Me) 2 CH 2 C(Me) 3 , —C(Me) 3 , —C(Me)HPh and Y(M) n -; wherein: 
 Y is a residue derived from a species that initiates free radical polymerization or is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 1  to C 18  alkoxy, substituted C 1  to C 18  alkoxy, C 6  to C 18  aryl, C 6  to C 18  substituted aryl, C 6  to C 18  aroyloxy, C 6  to C 18  substituted aroyloxy, (C 1  to C 18  alkoxy)carbonyloxy, (C 6  to C 18  aryloxy)carbonyloxy, and sulfate radical anions; and  
 all substituents are independently selected from the group that consists of epoxy, hydroxy, C 1  to C 18  alkoxy, acyl, acyloxy, alkoxycarbonyl, aryloxycarbonyl, cyano, silyl, halo, and C 1  to C 18  dialkylamino.  
 
     
     
         7 . A method for making the nitroxide of Formula (1):  
       
         
           
           
               
               
           
         
       
       wherein: 
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups that are in a geminal position with respect to each other can together form a 4-8 membered ring, and R groups that are in a cis position with respect to each other can together form a 4-8 membered ring;  
 X is selected from the group consisting of hydrogen, C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; X and R 3  can form a 5-8 membered ring; 
 comprising the steps: (i) preparing a colorless aqueous ammonium sulfide solution containing sodium thiocyanate by titrating an aqueous ammonium sulfide solution containing ammonium polysulfide with sodium cyanide under nitrogen; (ii) sequentially adding an aminonitrile and a ketone to the aqueous ammonium sulfide solution under nitrogen; (iii) adding base and then neutralizing; and (iv) oxidizing the reaction product of step (iii) to form the nitroxide.  
 
 
     
     
         8 . The method of  claim 7  wherein: 
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring; and  
 X is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; or X and R can form a 5-8 membered ring; and X and R 3  can form a 5-8 membered ring; with the proviso that at least one of R, R 1 , R 2 , R 3  and X is not methyl.  
 
     
     
         9 . The method of  claim 7  comprising stopping the process before step (iv) and isolating the reaction product of step (iii), and then practicing step (iv).  
     
     
         10 . The method of  claim 7  without intermediate isolation of the reaction product of step (iii) before the reaction in step (iv).  
     
     
         11 . A colorless aqueous ammonium sulfide solution containing sodium thiocyanate and substantially no ammonium polysulfide.  
     
     
         12 . A method for making an alkoxyamine of  claim 5  comprising one of steps (i) to (iii): 
 (i) adding Z. to the nitroxide  
                     
 (ii) adding Z-O to the amine  
                     
 (iii) alkylating the hydroxylamine derived from a nitroxide of Formula (1); wherein:  
 R, R 1 , R 2 , R 3  are each independently selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; R groups in a geminal position with respect to each other can together form a 4-8 membered ring; and R groups in a cis position with respect to each other can together form a 4-8 membered ring;  
 X is selected from the group consisting of C 1  to C 18  alkyl, substituted C 1  to C 18  alkyl, C 6  to C 18  aryl, C 6  to C 18  substituted aryl; acyl; X and R can form a 5-8 membered ring; and X and R 3  can form a 5-8 membered ring; and  
 Z is a group having at least one carbon atom such that the carbon centered radical Z. is capable of initiating free-radical polymerization of monomer (M).