the invention comprises a composition comprising at least one compound defined by the formula ## str1 ## wherein r is hydrogen , c 1 - 4 alkyl or a group ## str2 ## wherein g is a divalent hydrocarbyl - linking group and j , d , e and f are hereinafter defined ; wherein j and e independently are divalent linking groups selected from ## str3 ## wherein r &# 39 ; is hydrogen or c 1 - 4 alkyl ; d is a divalent hydrocarbyl group which lends hydrophobicity to the compound ; and f is a monovalent hydrocarbyl group which lends hydrophilicity to the compound . such compositions are useful as comonomers with water - soluble monomers such as acrylamide and acrylic acid which form water - dispersible thickening agents which are resistant to shear degradation and heat and have a broad range of salt tolerance . aqueous solutions thickened with such copolymers are useful in enhanced oil recovery processes as fluid mobility control agents , as fracturing fluids and drilling muds as well as hydraulic fluids and lubricants in many applications .