Raft polymerisation
A method of preparing polymer, the method comprising polymerizing one or more ethylenically unsaturated monomers of formula (I) where U is selected from H, C 1 -C 4 alkyl or halogen; V is halogen or of the form O-G where G is selected from —C(O)R 1 and —R 1 , or V is of the form NGG a where G is as defined above and G a is selected from H and R 1 , G and G a form together with N a heterocyclic ring, or V is of the form CH 2 G b where G b is selected from H, R 1 , OH, OR 1 , NR 1 2 , PR 1 2 , P(O)R 1 2 , P(OR 1 ) 2 , SR 1 , SOR 1 , and SO 2 R 1 ; and where the or each R 1 is independently selected from optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted heteroarylalkyl, optionally substituted alkylaryl, optionally substituted alkylheteroaryl, and an optionally substituted polymer chain, under the control of a RAFT agent of formula (II) or (III), where Y is a Lewis base moiety and Y* is an n-valent Lewis base moiety; X is O or NR 1 , R 1 is as defined above or forms together with Y or Y* and N a heterocyclic ring; m is an integer ≧1; n is an integer ≧2; and where R* is a m-valent radical leaving group that affords R*. which initiates free radical polymerization of the one or more ethylenically unsaturated monomers of formula (I), and R is a free radical leaving group that affords R. which initiates free radical polymerization of the one or more ethylenically unsaturated monomers of formula (I).
1. A RAFT agent of formula (XI),
where X is NR 1 , R 1 is independently selected from optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocyclyl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted heteroarylalkyl, optionally substituted alkylaryl, optionally substituted alkylheteroaryl, and an optionally substituted polymer chain;
R* is a m-valent radical leaving group that affords R*. which initiates free radical polymerisation of one or more ethylenically unsaturated monomers;
m is an integer ≧1;
R* is selected from the group consisting of primary, secondary and tertiary cyanoalkyls, primary, secondary and tertiary alkoxycarbonylalkyls, and primary, secondary and tertiary carboxyalkyls; and
where Y a is a Lewis base moiety selected from optionally substituted heteroaryl.
2. The RAFT agent of claim 1 , wherein R* is selected from cyanomethyl, 1-cyanoethyl, 2-cyanopropan-2-yl, ethoxycarbonylmethyl, 1-ethoxycarbonylethyl, 2-cyanobutan-2-yl, 1-cyanocyclohexyl, 2-cyano-4-methylpentan-2-yl, 2-cyano-4-methoxy-4-methylpentan-2-yl, 2-cyano-4-carboxybutan-2-yl, 2-cyano-5-hydroxypentan-2-yl, cyano(phenyl)methyl, 2-alkoxycarbonylpropan-2-yl, 1-(butylamino)-2-methyl-1-oxopropan-2-yl, phenyl(ethoxycarbonyl)methyl, 1-(cyclohexylamino)-2-methyl-1-oxopropan-2-yl, 1-(2-hydroxyethylamino)-2-methyl-1-oxopropan-2-yl, and 1-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-ylamino)-2-methyl-1-oxopropan-2-yl, 2-(4,5-dihydro-1H-imidazol-2-yl)propan-2-yl, and 2-(1-(2-hydroxyethyl)-4,5-dihydro-1H-imidazol-2-yl)propan-2-yl.
3. The RAFT agent of claim 1 selected from:
where R x is selected from an optionally substituted alky group or R y ; and R y is an optionally substituted pyridyl group (all isomers).
4. The RAFT agent of claim 3 , wherein R* is selected from primary, secondary or tertiary cyanoalkyl.