A method of producing a polymeric material including subjecting a starting material to conditions under which polymerisation occurs. The starting material includes a group of sub-formula (XIII) where R16 is selected from hydrogen, halo, nitro, hydrocarbyl, optionally substituted or interposed with functional groups, or R2 and R3 are independently selected from (CR6R7)n or a group CR8R9, CR6R7CR8R9 or CR8R9CR6R7 where n is 0, 1 or 2 and R6 and R7 are independently selected from hydrogen or alkyl, and either one of R8 or R9 is hydrogen and the other is an electron withdrawing group, or R8 or R9 together form an electron withdrawing group. R4 and R5 are independently selected from CH or CR1o where CR1o is an electron withdrawing group, X1 is a group CX2X3, Y1 is a group CY2Y3, and X2 X3, and, if present, Y2 and Y3, are each a C1 to C4 alkyl group.