Diamine compound represented by one of the general formula (Ia): wherein: A, B each independently represents 1,4-phenylene, which is unsubstituted or mono- or poly-substituted by a halogen atom, and/or by acryloyloxy or methacryloyloxy, and/or by an alkoxy, alkylcarbonyloxy or an alkyloxycarbonyl group, having from 1 to 10 carbon atoms, and D represents a straight-chain or branched alkyl residue having from 1 to 20 carbon atoms E represents an oxygen atom; and S 1 is a single bond, S 2 represents a single bond or a straight-chain alkylene group, having from 1 to 12 carbon atoms, wherein one or more -CH 2 -groups may independently be replaced by a group of formula, -(Z 1 -C 1) a1 -(Z 2 -C 2) a2 - wherein: C 1, C 2 each independently represents 1,4-phenylene or 1,4-cyclohexylene; and Z 1, Z 2 each independently represents -COO-, -OCO-, -CH 2 -CH 2 -, -OCH 2 -, -CH 2 O- -CH=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, or a single bond; and a 1, a 2 each independently represents 0 or 1; and F represents a substituted or unsubstituted aromatic diamino group having from 1 to 40 carbon atoms selected from formula: HN(R 5)-(C 3) a3 -(Z 4 -C 4)a4 -N(R 6)H wherein: R 5 and R 6 are identical and represent a hydrogen atom, a methyl, an ethyl or an isopropyl group, and C 3, C 4 represent benzene; and Z 4 represents a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond or represents a substituted or unsubstituted straight-chain or branched alkylene group having from 1 to 16 carbon atoms, in which one or more -CH 2 - groups may be replaced by a heteroatom and/or by a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond and/or one or more carbon-carbon single bonds may be replaced by a carbon-carbon double bond or a carbon-carbon triple bond; and a 3, a 4 each independently represents an integer from 0 to 2, such that a 3 + a 4 ≤ 3; and wherein: F is linked to group S 2 in formula (Ia) via group C 3 and/or group Z and/or group C 4, with the proviso that at least one of a 3 and a 4 is not equal to zero, and X, Y each independently represent hydrogen, fluorine, chlorine, cyano, and n is 1 or 2. A, B each independently represents 1,4-phenylene, which is unsubstituted or mono- or poly-substituted by a halogen atom, and/or by acryloyloxy or methacryloyloxy, and/or by an alkoxy, alkylcarbonyloxy or an alkyloxycarbonyl group, having from 1 to 10 carbon atoms, and D represents a straight-chain or branched alkyl residue having from 1 to 20 carbon atoms E represents an oxygen atom; and S 1 is a single bond, S 2 represents a single bond or a straight-chain alkylene group, having from 1 to 12 carbon atoms, wherein one or more -CH 2 -groups may independently be replaced by a group of formula, -(Z 1 -C 1) a1 -(Z 2 -C 2) a2 - C 1, C 2 each independently represents 1,4-phenylene or 1,4-cyclohexylene; and Z 1, Z 2 each independently represents -COO-, -OCO-, -CH 2 -CH 2 -, -OCH 2 -, -CH 2 O- -CH=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, or a single bond; and a 1, a 2 each independently represents 0 or 1; and Z 1, Z 2 each independently represents -COO-, -OCO-, -CH 2 -CH 2 -, -OCH 2 -, -CH 2 O- -CH=CH-, -C≡C-, -CH=CH-COO-, -OCO-CH=CH-, or a single bond; and a 1, a 2 each independently represents 0 or 1; and F represents a substituted or unsubstituted aromatic diamino group having from 1 to 40 carbon atoms selected from formula: HN(R 5)-(C 3) a3 -(Z 4 -C 4)a4 -N(R 6)H wherein: R 5 and R 6 are identical and represent a hydrogen atom, a methyl, an ethyl or an isopropyl group, and C 3, C 4 represent benzene; and Z 4 represents a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond or represents a substituted or unsubstituted straight-chain or branched alkylene group having from 1 to 16 carbon atoms, in which one or more -CH 2 - groups may be replaced by a heteroatom and/or by a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond and/or one or more carbon-carbon single bonds may be replaced by a carbon-carbon double bond or a carbon-carbon triple bond; and a 3, a 4 each independently represents an integer from 0 to 2, such that a 3 + a 4 ≤ 3; and wherein: R 5 and R 6 are identical and represent a hydrogen atom, a methyl, an ethyl or an isopropyl group, and C 3, C 4 represent benzene; and Z 4 represents a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond or represents a substituted or unsubstituted straight-chain or branched alkylene group having from 1 to 16 carbon atoms, in which one or more -CH 2 - groups may be replaced by a heteroatom and/or by a group selected from -CH -, -CH(CH 3)-, -C(CH 3) 2 -, -CO-, -COO-, -COCF 2 -, -CF 2 CO- or a single bond and/or one or more carbon-carbon single bonds may be replaced by a carbon-carbon double bond or a carbon-carbon triple bond; and a 3, a 4 each independently represents an integer from 0 to 2, such that a 3 + a 4 ≤ 3; and wherein: F is linked to group S 2 in formula (Ia) via group C 3 and/or group Z and/or group C 4, with the proviso that at least one of a 3 and a 4 is not equal to zero, and X, Y each independently represent hydrogen, fluorine, chlorine, cyano, and n is 1 or 2.