l ethers of formula CH2???CR1CH2OAmBnApR2 wherein R1 is chosen from hydrogen atoms and methyl groups, A is chosen from propyleneoxy and butyleneoxy groups, B is ethyleneoxy, n is equal to zero or an integer less than or equal to 200, such as less than 100, m and p are zero or an integer less than n, and R2 is chosen from hydrophobic groups of at least 8 carbon atoms, such as C8-C30; and (vi) nonio