Effect of Additives on the Cloud Points of Aqueous Solutions of Ethylene Oxide–Propylene Oxide–Ethylene Oxide Block Copolymers

✍ Scribed by Rodrigo Cardoso da Silva; Watson Loh

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 84 KB
• Volume: 202
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1998.5456

✦ Synopsis

pend strongly on the copolymer composition, with higher The cloud points of aqueous solutions of eight ethylene oxide values for those containing a larger percentage of EO units. (EO)/propylene oxide (PO) triblock copolymers were measured Typically, copolymers with more than 70% EO present cloud in the presence of eight additives. The additives increased these points above 100ЊC (6). temperatures in the following sequence: urea, dimethylurea, tetra-One of the strategies for increasing the cloud points of propylammonium bromide õ nicotinamide õ sodium thiocyanate nonionic surfactant solutions is using additives, usually reõ sodium p-toluenesulfonate õ sodium xylenesulfonate õ tetraferred to as hydrotropes, chaotropes, or antihydrophobic butylammonium bromide. No similar trend could be derived in agents (7), known for causing aqueous solubility increase. relation to the polymers structure or composition. The same addi-Pandya et al. ( ) have described the effect of a variety of tives were tested with two ethoxylated nonylphenols and with three PPO and were only effective to increase the cloud points of com-compounds on the cloud points of one of these copolymers pounds containing EO chains. This observation suggests that these (L 64), being able to identify ''salting in'' and ''salting additives affect the solvation capacity of water in relation to the out'' effects. For electrolytes, these effects were observed EO units, especially at higher temperatures.