A modified particle comprising a particle having attached a group having the formula: wherein A represents at least one aromatic group or at least one alkyl group; R1 represents a bond, an arylene group, an alkylene group, wherein R4 is an alkyl or alkylene group or an aryl or arylene group; R2 and R3, which can be the same or different, represent hydrogen, an alkyl group, an aryl group, ???OR5, ?