2023 年 33 巻 1_2 号 p. 1-6
An amphiphilic aryl-ether AB2-type dendron(1)bearing oligo ethylene glycol(OEG)chains exhibited lower critical solution temperature behavior in aqueous solutions. In the presence of the salting-out salts(Na2SO4, NaCl, and NaBr), the cloud points of 1 decreased linearly with increasing salt concentration. The slope of the linear decrease changed with the anion type in the order, SO42- > Cl- > Br-. In the presence of the salting-in salts(NaSCN and NaI), the cloud points of 1 increased non linearly with increasing salt concentration. The shape of these curves can be well fitted by adding a Langmuir binding isotherm to the linear term used for the salting-out salts. When monohydric alcohols(ethanol and 1-propanol)were added to the aqueous solutions of 1, the cloud points barely changed but were reduced after adding polyhydric alcohols(ethylene glycol, xylitol, and D-sorbitol). The salt effect on the cloud points of 1 was negligible in the aqueous polyhydric alcohol solutions. Conversely, the addition of monohydric alcohols to the aqueous solutions could amplify the salt effect on the cloud points. The alkyl groups of monohydric alcohols could be hydrated by water molecules accompanied by the formation of a hydration shell with a clathrate-like structure. Hence, free water molecules are consumed by adding monohydric alcohols to the aqueous solutions. Overall, the amplifi cation of the salt eff ect on the clouding points of 1 could be deduced by increasing the salt concentration around 1.