Sulfobetaine-based terpolymers used as thickeners for aqueous salt solutions, especially oilfield brines, contain optionally substituted acrylamide, hydroxy-alkyl (meth)acrylate and sulfobetaine monomer units

摘要

Terpolymers based on sulfobetaines, containing 5-79 mol% optionally N-substituted (meth)acrylamide units, 20-94 mol% hydroxyalkyl (meth)acrylate units and 1-75 mol% vinyl monomer units with tetra-organyl ammonium- or pyridinium-sulfobetaine groups Terpolymers based on sulfobetaines, containing (a) 5-79 mol% units of formula (I), (b) 20-94 mol% units of formula (II) and (c) 1-75 mol% units of formula (III): R1 = H or methyl; R2, R3 = H, 1-4C alkyl or phenyl; m = 1-4; X = a group of formula -CO-O-Y-R4-N+R2R3-R4-SO3-, -O-R4-N+(R2R3)-(CH2)n-CH(SO3-)-(CH2)n-Py or -(Py')+-R4-SO3-; Y = O or NH; R4 = -(CH2)m-, 1,4-phenylene, pyridine-3,6-diyl or pyridine-2,5-diyl; Py = 1-pyridyl with a substituent R1 in position 2; Py' = pyridinium-2-yl with a substituent -R4-SO3- on the nitrogen atom; n = 0-3 . An Independent claim is also included for a process for the production of these terpolymers from (meth)acrylamide, hydroxyalkyl (meth)acrylate and sulfobetaine monomers by homogeneous radical polymerisation in aqueous solution at 10-100 deg C.