TECHNOLOGY FOCUS - POLYMERS - Preparation: No general preparation of the hyperbranched polyester amide is given. Preferred Components: The hyperbranched polyester amide has a cloud point of at least 75 degrees C and where the at least one neutral end group on it comprises: at least one zwitterion that has an anionic carboxylate attached to a positively charged nitrogen atom; has a cloud point of at least 80 degrees C and where the at least one neutral end group comprises a group of formula (i). The hyperbranched polyester amide comprises cationic functional groups on it and at least one carboxylate counter anion(s) obtained and/or obtainable from at least one organic (mono or poly) carboxylic acid (including acidic and/or their hydrogen salts); at least one carboxylate counter ion(s) obtained and/or obtainable from citric acid and/or their suitable acid salt; core obtained and/or obtainable from hexahydrophthalic anhydride. The hyperbranched polyester amide has a cloud point of at least 100 degrees C in BRINE. The hyperbranched polyester amide comprises a core obtained and/or obtainable from at least one hexahydrophthalic anhydride, cationic end group and citrate counter anion, where the polyester amide has a cloud point of at least 100 degrees C in BRINE.R1,R2=optionally substituted 1-6C hydrocarbyl groups (preferably 1-6C hydrocarbyl groups, especially both methyl (i.e. betaine group)). EXAMPLE - A double walled glass reactor, which was heated by using thermal oil, fitted with a mechanical stirrer, distillation head, vacuum and nitrogen connection was heated to 70 degrees C. The reactor was charged with N,N-bis(N'N'-dimethylaminopropyl) amine (190.9 g) and diisopropanol amine (91.3 g) and hexahydrophthalic anhydride (220.2 g) was added and then the reaction mixture was stirred for 2 hours. The temperature was increased to 160 degrees C and the pressure was gradually reduced to a final pressure of less than 10 mbar to remove reaction water. Heating and vacuum were maintained until the residual carboxylic acid content was less than 0.3 meq/g (tritrimetrical analysis) to obtain a product having acid value of 10.5 mgKOH/g, amine content of 3.20 meq/g (tritrimetrical analysis) and number average molecular weight (Mn) of 1675 wt.%. The obtained product (175 g) was dissolved in water (175 g), sodium chloro acetate (36.2 g) and water (36.2 g) were added. The reaction mixture was stirred at 80 degrees C until 1H-NMR analysis showed complete conversion of the chloroacetate to obtain betaine-type functional polyester amide.