Aqueous dispersions of polymer particles

Abstract

The invention provides a method for preparing an aqueous dispersion of polymer particles comprising the following steps: (i) preparing a dispersion having a continuous aqueous phase, a dispersed organic phase comprising one or more ethylenically unsaturated monomers, and an amphiphilic RAFT agent as a stabiliser for said organic phase, and (ii) polymerising said one or more ethylenically unsaturated monomers under the control of said amphiphilic RAFT agent to form said aqueous dispersion of polymer particles, novel amphiphilic RAFT agents for use in this method, novel RAFT agents useful in making these amphiphilic RAFT agents and methods for their manufacture.

1 . An amphiphilic RAFT agent of general formula (4a) 
     
       
         
         
             
             
         
       
       where each X is independently a polymerized residue of an ethylenically unsaturated monomer; 
       n is 1 to 100; 
       R 1  is —CH(CH 3 )COOH, —CH(CO 2 H)CH 2 CO 2 H or —CH(CH 3 )CONR a R b , where R a  and R b  are the same or different and independently selected from H, C 1 -C 6  alkyl, C 1 -C 6  alkoxy, C 6 -C 12  aryl, C 7 -C 18  alkylaryl or C 6 -C 12  heteroaryl, each of which is substituted with one or more hydrophilic groups selected from —CO 2 H, —CO 2 R′, —SO 3 H, —OSO 3 H, —SOR′, —OP(OH) 2 , —P(OH) 2 , —PO(OH) 2 , —OH, —OR′, —(OCH 2 —CHR) w —OH, —CONH 2 , CONHR′, CONR′R″, —NR′R″, —N+R′R″R′″, where R is selected from C 1 -C 6  alkyl, w is 1 to 10, R′, R″ and R′″ are independently selected from C 1 -C 6  alkyl and C 6 -C 12  aryl which are optionally substituted with one or more hydrophilic substituents selected from —CO 2 H, —SO 3 H, —OSO 3 H, —OH, —(COCH 2 CHR) w —OH, —CONH 2 , —SOR and SO 2 R, and salts thereof; and 
       Z is selected from optionally substituted alkyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylthio, optionally substituted arylalkylthio, and optionally substituted acylamino. 
     
   
   
       2 . A RAFT agent of general formula (5a) 
     
       
         
         
             
             
         
       
       where R 1  is —CH(CO 2 H)CH 2 CO 2 H, or —CH(CH 3 )CONR a R b , where R a  and R b  are the same or different and independently selected from H, C 1 -C 6  alkyl, C 1 -C 6  alkoxy, C 6 -C 12  aryl, C 7 -C 18  alkylaryl or C 6 -C 12  heteroaryl, each of which is substituted with one or more hydrophilic groups selected from —CO 2 H, —CO 2 R′, —SO 3 H, —OSO 3 H, —SOR′, —SO 2 R′, —OP(OH) 2 , —P(OH) 2 , —PO(OH) 2 , —OH, —OR′, —(OCH 2 —CHR) w —OH, —CONH 2 , CONHR′, CONR′R″, —NR′R″, —N+R′R″R′″, where R is selected from C 1 -C 6  alkyl, w is 1 to 10, R′, R″ and R′″ are independently selected from C 1 -C 6  alkyl and C 6 -C 12  aryl which are optionally substituted with one or more hydrophilic substituents selected from —CO 2 H, —SO 3 H, —OSO 3 H, —OH, —(COCH 2 CHR), OH, —CONH 2 , —SOR and SO 2 R, and salts thereof; and 
       Z is selected from optionally substituted alkyl, optionally substituted aryl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylthio, optionally substituted arylalkylthio, and optionally substituted acylamino. 
     
   
   
       3 . A RAFT agent of general formula (5a) 
     
       
         
         
             
             
         
       
       where R 1  is —CH(CH 3 )COOH; and 
       Z is selected from the group consisting of optionally substituted alkyl, substituted aryl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylthio, optionally substituted arylalkylthio, and optionally substituted acylamino. 
     
   
   
       4 . A method of preparing a RAFT agent by conjugate addition of a dithiocarbonyl compound to an α,β-unsaturated carbonyl or thiocarbonyl compound. 
   
   
       5 . The method according to  claim 4  comprising the conjugate addition of a compound of formula (I): 
     
       
         
         
             
             
         
       
     
     where M is hydrogen, an organic cation, or a metal and Z is any group that can promote sufficient reactivity of the thiocarbonyl group towards radical addition while not slowing the rate of fragmentation to the extent that there is unacceptable retardation of polymerization, to the double bond of compound of formula (II): 
     
       
         
         
             
             
         
       
       where EWG is an electron withdrawing group selected from —CO 2 H, —CO 2 R 2 , —COR 2 , —CSR 2 , —CSOR 2 , —COSR 2 , —CN—SO 2 R 2 , —SOR 2 , —CONH 2 , —CONHR 2 , —CONR 2   2 ; 
       R 3  is selected from H, C 1-6  alkyl, or together with either R 4  or EWG forms a —C(O)O-group; 
       R 4  is selected from H, C 1-6  alkyl, aryl, heteroaryl, —CO 2 H, —CO 2 R 2 , —COR 2 , —CSR 2 , —CSOR 2 , —COSR 2 , —CN—SO 2 R 2 , —SOR 2 , —CONH 2 , —CONHR 2 , —CONR 2   2 ; and 
       R 5  is selected from H, C 1-6  alkyl, aryl, heteroaryl; 
       wherein R 2  is selected from the group consisting of optionally substituted C 1 -C 18  alkyl, optionally substituted C 2 -C 18  alkenyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted heteroarylalkyl, optionally substituted alkaryl, optionally substituted alkylheteroaryl and polymer chains wherein the substituents are independently selected from the group consisting of alkyleneoxidyl (epoxy), hydroxy, alkoxy, acyl, acyloxy, formyl, alkylcarbonyl, carboxy, sulfonic acid, alkoxy- or aryloxy-carbonyl, isocyanato, cyano, silyl, halo, amino, including salts and derivatives thereof. 
     
   
   
       6 . The method according to  claim 5 , wherein Z is selected from optionally substituted alkoxy, optionally substituted aryloxy, optionally substituted alkyl, optionally, substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [—P(═O)OR 2   2 ], dialkyl- or diaryl-phosphinyl [—P(═O)R 2   2 ], optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, and a polymer chain formed by any mechanism; wherein R 2  is selected from the group consisting of optionally substituted C 1 -C 18  alkyl, optionally substituted C 2 -C 18  alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted alkaryl. 
   
   
       7 . A paint, filler, adhesive, primer or sealant comprising an aqueous dispersion of polymer particles, wherein the aqueous dispersion of polymer particles is prepared according to a method comprising the following steps:
 (i) preparing a dispersion having a continuous aqueous phase, a dispersed organic phase comprising one or more ethylenically unsaturated monomers, and an amphiphilic RAFT agent as a stabilizer for said organic phase, and   (ii) polymerising said one or more ethylenically unsaturated monomers under the control of said amphiphilic RAFT agent to form said aqueous dispersion of polymer particles.   
   
   
       8 . The paint, filler, adhesive, primer or sealant of  claim 7 , wherein the dispersion of step (i) is prepared by forming a solution of amphiphilic RAFT agent in water and polymerising added ethylenically unsaturated monomer under the control of the amphiphilic RAFT agent. 
   
   
       9 . The paint, filler, adhesive, primer or sealant of  claim 7 , wherein the dispersion of step (i) is prepared by forming a composition comprising water insoluble amphiphilic RAFT agent and ethylenically unsaturated monomer, and combining this composition with water. 
   
   
       10 . The paint, filler, adhesive, primer or sealant of  claim 9 , wherein the RAFT agent is dissolved in monomer, optionally together with organic solvent. 
   
   
       11 . The paint, filler, adhesive, primer or sealant of  claim 7 , wherein the dispersion of step (i) is prepared by forming a composition comprising water insoluble amphiphilic RAFT agent and water, and combining this composition with ethylenically unsaturated monomer. 
   
   
       12 . The paint, filler, adhesive, primer or sealant of  claim 7 , wherein the amphiphilic RAFT agent is of general formula (4): 
     
       
         
         
             
             
         
       
       where each X is independently a polymerised residue of an ethylenically unsaturated monomer, n is an integer ranging from 0 to 100, R 1  is an organic group optionally substituted with one or more hydrophilic groups and Z is any group that can promote sufficient reactivity of the thiocarbonyl group towards radical addition while not slowing the rate of fragmentation to the extent that there is unacceptable retardation of polymerization. 
     
   
   
       13 . The paint, filler, adhesive, primer or sealant of  claim 12 , wherein R 1  is selected from C 1 -C 6  alkyl, C 1 -C 6  alkoxy aryl or heteroaryl, each of which is substituted with one or more hydrophilic groups selected from —CO 2 H, —CO 2 R′, —SO 3 H, —OSO 3 H, —SOR′, —SO 2 R′, —OP(OH) 2 , —P(OH) 2 , —PO(OH) 2 , —OH, —OR′, —(OCH 2 —CHR) w —OH, —CONH 2 , CONHR′, CONR′R″, —NR′R″, —N+R′R″R′″, where R is selected from C 1 -C 6  alkyl, w is 1 to 10, R″ and R′″ are independently selected from alkyl and aryl which are optionally substituted with one or more hydrophilic substituents selected from —CO 2 H, —SO 3 H, —OSO 3 H, —OH, —(COCH 2 CHR) w —OH, —CONH 2 , —SOR and SO 2 R, and salts thereof, and wherein Z is selected from optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy-phosphinyl [—P(═O)OR 2   2 ], dialkyl- or diaryl-phosphinyl [P(═O)R 2   2 ], optionally substituted acylamino, optionally substituted acylamino, optionally substituted amino, R 1 —(X) n —S— and a polymer chain formed by any mechanism; wherein R 1 ; X and n are as defined herein or in  claim 11 , and R 2  is selected from the group consisting of optionally substituted C 1 -C 18  alkyl, optionally substituted C 2 -C 18  alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, and optionally substituted alkaryl. 
   
   
       14 . The paint, filler, adhesive, primer or sealant of  claim 7 , wherein the amphiphilic RAFT agent is of general formula (4): 
     
       
         
         
             
             
         
       
     
     where each X is independently a polymerised residue of an ethylenically unsaturated monomer, n is an integer ranging from 0 to 100, Z is any group that can promote sufficient reactivity of the thiocarbonyl group towards radical addition while not slowing the rate of fragmentation to the extent that there is unacceptable retardation of polymerization, and wherein R 1  is an organic group substituted with one or more hydrophobic groups.