A salt-tolerant star macromolecule that when dissolved in water at a concentration of 0.4 wt.% forms a homogeneous gel and has a dynamic viscosity of at least 10,000 cP in a 0.4 wt.% NaCl aqueous solution when measured at a temperature of 25 °C and a shear rate of 1 rpm, according to the Salt Tolerance Test; wherein the salt-tolerant star macromolecule comprises a plurality of polymeric arms comprising at least two types of arms, wherein: i) a first polymeric arm that extends beyond a second polymeric arm; and ii) the first polymeric arm has a salt-tolerant-enhancing segment on its distal end; and wherein the monomeric residues of one or more polymerized salt-tolerant-enhancing monomers present within the salt-tolerant-enhancing polymeric segment comprise: methyl acrylate, methyl methacrylate, methyl ethacrylate, ethyl acrylate, ethyl methacrylate, ethyl ethacrylate, n-butyl acrylate, n-butyl methacrylate, n-butyl ethacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl ethacrylate, N-octyl acrylamide, 2-methoxyethyl acrylate, 2-hydroxyethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, acrylic acid, methacrylic acid, N-t-butylacrylamide, N-sec- butylacrylamide, N,N-dimethylacrylamide, N,N-dibutylacrylamide, N,N-dihydroxyethyllacrylamide, 2-hydroxyethyl methacrylate, benzyl acrylate, 4-butoxycarbonylphenyl acrylate, butyl acrylate, 4-cyanobutyl acrylate, cyclohexyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, heptyl acrylate, iso-butyl acrylate, 3-methoxybutyl acrylate, 3-methoxypropyl acrylate, N-butyl acrylamide, diethyleneglycolethyl acrylate, 2-fluoroethyl acrylate, or 2-fluoroethyl methacrylate. wherein the salt-tolerant star macromolecule comprises a plurality of polymeric arms comprising at least two types of arms, wherein: i) a first polymeric arm that extends beyond a second polymeric arm; and ii) the first polymeric arm has a salt-tolerant-enhancing segment on its distal end; and i) a first polymeric arm that extends beyond a second polymeric arm; and ii) the first polymeric arm has a salt-tolerant-enhancing segment on its distal end; and wherein the monomeric residues of one or more polymerized salt-tolerant-enhancing monomers present within the salt-tolerant-enhancing polymeric segment comprise: methyl acrylate, methyl methacrylate, methyl ethacrylate, ethyl acrylate, ethyl methacrylate, ethyl ethacrylate, n-butyl acrylate, n-butyl methacrylate, n-butyl ethacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl ethacrylate, N-octyl acrylamide, 2-methoxyethyl acrylate, 2-hydroxyethyl acrylate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, acrylic acid, methacrylic acid, N-t-butylacrylamide, N-sec- butylacrylamide, N,N-dimethylacrylamide, N,N-dibutylacrylamide, N,N-dihydroxyethyllacrylamide, 2-hydroxyethyl methacrylate, benzyl acrylate, 4-butoxycarbonylphenyl acrylate, butyl acrylate, 4-cyanobutyl acrylate, cyclohexyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, heptyl acrylate, iso-butyl acrylate, 3-methoxybutyl acrylate, 3-methoxypropyl acrylate, N-butyl acrylamide, diethyleneglycolethyl acrylate, 2-fluoroethyl acrylate, or 2-fluoroethyl methacrylate. <EOS>