To investigate the salting-in or sating-out effects produced by the addition of ammonium salts to aqueous solutions of thermosensitive polymers, a systematic study on the cloud point properties of PPG1000 aqueous solutions is performed in the presence of a series of these salts. In order to cover a range of hydrophilic and hydrophobic nature of salts, ammonium chloride (NH4Cl), ammonium bromide (NH4Br), tetra ethyl ammonium bromide (TEAB), tetra propyl ammonium bromide (TPAB), tetra butyl ammonium bromide (TBAB), tetra butyl ammonium chloride (TBAC), and dodecyl tri methyl ammonium bromide (DTAB) were investigated. The results show that inorganic ammonium salts (NH4Cl and NH4Br) which have unfavourable interactions with PPG, lower the cloud point temperature of aqueous polymer solutions and so induce salting-out effect. However, the organic ammonium salts (TEAB, TPAB, TBAB, TBAC, DTAB), which have hydrocarbon portions in their structures, interact with PPG favourably, so elevate cloud point temperature and induce salting-in effect on aqueous PPG solutions.
