Polymer derived from acrylonitrile

1. A method for producing poly(acrylonitrile) homo- or co-polymers by RAFT polymerisation, the method comprising polymerising acrylonitrile and optionally one or more ethylenically unsaturated co-monomers under the control of a RAFT agent, wherein (i) the mole ratio of the polymerisable monomers to the RAFT agent is at least 4,000, and (ii) the mole ratio of the RAFT agent to initiator compound is no more than 3.

2. The method according to claim 1 , wherein the polymerisation is conducted at a temperature of no more than 70° C.

3. The method according to claim 1 , wherein the acrylonitrile is copolymerised with one or more ethylenically unsaturated co-monomers selected from acrylic acid, methacrylic acid, itaconic acid, allysulfonic acid, maleic acid, crotonic acid, ammonia acrylate, butyl methacrylate, carboxyethyl (meth)acrylate, hydroxyethyl (meth)acrylate, propyl acrylate, stearyl acrylate, isobutyl methacrylate, methyl methacrylate, ethyl methacrylate, vinyl acetate, methyl acrylate, vinyl chloride, vinylidine chloride, styrene and its derivatives, acylamide and methacrylamide and its derivatives, 3-ammoniumcarboxylate-3-butenoic acid methyl ester, vinylsilazanes, vinylcyclic silazanes, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, glycerol allyloxy di(meth)acrylate, 1,1,1-tris(hydroxymethyl)ethane di(meth)acrylate, 1,1,1-tris(hydroxymethyl)ethane tri(meth)acrylate, 1,1,1-tris(hydroxymethyl)propane di(meth)acrylate, 1,1,1-tris(hydroxymethyl)propane tri(meth)acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl phthalate, diallyl terephthalte, divinyl benzene, methylol (meth)acrylamide, triallylamine, oleyl maleate, glyceryl propoxy triacrylate, allyl methacrylate, methacrylic anhydride, 1,1,3,3-Tetramethyl-1,3-divinyldisilazane; 1,3-divinyltetramethyldisiloxane, methylenebis (meth) acrylamide, glycerol 1,3-diglycerolate diacrylate, diurethane dimethacrylate, ammonium and alkali metal salts and alkyl esters of the acid containing monomers, and combinations thereof.

4. The method according to claim 1 , wherein the RAFT agent used is a dithioester or trithiocarbonate RAFT agent.

5. The method according to claim 4 , wherein the dithioester RAFT agent is a dithiobenzoate RAFT agent.

6. The method according to claim 1 , wherein the RAFT agent used is a dithioester or trithiocarbonate RAFT agent in combination with a dithiocarbamate or xanthate RAFT agent.

7. The method according to claim 4 , wherein the dithioester or trithiocarbonate RAFT agent is cyano functionalised, carboxylic acid functionalised, or cyano and carboxylic acid functionalised.

8. The method according to claim 1 , wherein the RAFT agent used is selected from one or more of 1-8, or is provided by a RAFT agent precursor compound selected from 9-11:

where the or each R is independently selected from H or CH 3 , the or each R′ is independently selected from H, CH 3 , or CN, the or each n is independently n=0-15, and the or each m is independently m=0-10.

9. The method according to claim 8 , wherein the RAFT agent is selected from 1 or 5.

10. The method according to claim 1 , wherein the polymerisation is performed in a reaction medium and the reaction medium is selected from dimethylsulfoxide, ethylene carbonate, propylene carbonate, and combinations thereof.

11. The method according to claim 1 , wherein the resulting poly(acrylonitrile) homo- or co-polymers have a number average molecular weight (M n ) of at least 400,000 g/mol and a dispersity ( ) of less than 1.25.

12. A method of producing carbon fibre, the method comprising carbonising a fibre comprising poly(acrylonitrile) homo- or co-polymers produced according to claim 1 .

13. Carbon fibre comprising carbonised residue of poly(acrylonitrile) homo- or co-polymer produced according to claim 1 .

14. The method according to claim 1 wherein the resulting poly(acrylonitrile) homo- or co-polymers are formed into fibre.