abstract |
Compounds of formula (I): wherein p is at least 1 and n is at least 1 and less than or equal to p; Ar is a polycyclic aromatic moiety, R 1 is hydrogen or an optionally substituted hydrocarbyl group, and each R 2 , R 3 and R 4 is independently an optionally substituted hydrocarbyl group with the proviso that R 2 , At least one of R 3 and R 4 has at least 6 carbon atoms. |