Polymer particles for use in electrophoretic devices comprising monomer units of a) at least one ethylenically unsaturated monomer; b) at least one polymerisable ionic liquid X-R-A - C + wherein X is a polymerisable group, R is a spacer group, A - is an anion, and C + is a cation selected from phosphonium, sulfonium, ammonium, uronium, thiouronium, guanidinium, imidazolium, pyrazolium, pyrazolinium, pyridinium, pyrrolidinium, triazolium, morpholinium, and piperidinium cations and cations of the following formulae: where the substituents R1' to R4' each, independently of one another, denote - a straight-chain or branched alkyl having 1-20 C atoms, which optionally can be partially fluorinated, but not in α-position to hetero-atom, and which can also include oxygen or/and sulfur atoms in any positions in between carbon atoms; - saturated, partially or fully unsaturated cycloalkyl having 5-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, where the substituents R1', R2', R3' and/or R4' together may also form a ring system; c) optionally at least one polymerisable dye, and d) at least one polymerisable steric stabiliser selected from poly(dimethylsiloxane) macromonomers with at least one polymerisable group. a) at least one ethylenically unsaturated monomer; b) at least one polymerisable ionic liquid X-R-A - C + wherein X is a polymerisable group, R is a spacer group, A - is an anion, and C + is a cation selected from phosphonium, sulfonium, ammonium, uronium, thiouronium, guanidinium, imidazolium, pyrazolium, pyrazolinium, pyridinium, pyrrolidinium, triazolium, morpholinium, and piperidinium cations and cations of the following formulae: where the substituents R1' to R4' each, independently of one another, denote - a straight-chain or branched alkyl having 1-20 C atoms, which optionally can be partially fluorinated, but not in α-position to hetero-atom, and which can also include oxygen or/and sulfur atoms in any positions in between carbon atoms; - saturated, partially or fully unsaturated cycloalkyl having 5-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, where the substituents R1', R2', R3' and/or R4' together may also form a ring system; R1' to R4' each, independently of one another, denote - a straight-chain or branched alkyl having 1-20 C atoms, which optionally can be partially fluorinated, but not in α-position to hetero-atom, and which can also include oxygen or/and sulfur atoms in any positions in between carbon atoms; - saturated, partially or fully unsaturated cycloalkyl having 5-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, - a straight-chain or branched alkyl having 1-20 C atoms, which optionally can be partially fluorinated, but not in α-position to hetero-atom, and which can also include oxygen or/and sulfur atoms in any positions in between carbon atoms; - saturated, partially or fully unsaturated cycloalkyl having 5-7 C atoms, which may be substituted by alkyl groups having 1-6 C atoms, where the substituents R1', R2', R3' and/or R4' together may also form a ring system; c) optionally at least one polymerisable dye, and d) at least one polymerisable steric stabiliser selected from poly(dimethylsiloxane) macromonomers with at least one polymerisable group.