In one embodiment, the present invention relates to a modified particle comprising a particle having attached a group having the formula: ##STR10## wherein Ar represents an aromatic group which is attached to the particle; R1 represents a bond, an arylene group, an alkylene group, ##STR11## wherein R4 is an alkyl or alkylene group or an aryl or arylene group; R2 and R3, which can be the same or di