Phase Behavior of a “Clouding” Nonionic Polymer in Water. Effects of Hydrophobic Modification and Added Surfactant on Phase Compositions

Abstract

Cloud point curves and conjugate coexistence curves for the quasi-binary water systems of ethyl(hydroxyethyl)cellulose (EHEC) and its hydrophobically modified analogue (HMEHEC) have been determined. The cloud point curves are remarkably independent of the polymer concentration up to as high as 20 wt % polymer, and they are clearly different from the coexistence curves. This is interpreted as an effect of the multicomponent nature of the polymer. Hydrophobic modification of EHEC lowers the cloud point by approximately 15 °C. On heating above the cloud point, EHEC redistributes to the concentrated phase, but, however, a substantial amount of the polymer remains in the dilute phase even far above the cloud point. For HMEHEC, essentially all polymer is found throughout in the concentrated phase. Addition of the anionic surfactant, sodium octylbenzenesulfonate (SOBS), affects the phase behavior. Small amounts of SOBS cause a swelling of the concentrated phase for both EHEC and HMEHEC, due to an electrostatic repulsion between polymer−surfactant aggregates. On further addition of SOBS, a dissolution of polymer from the concentrated phase is observed for EHEC. For HMEHEC, the surfactant binding swells the concentrated phase until the one-phase region is reached.

Interactions between Local Anaesthetic Agents and Poly(N-isopropyl acrylamide) through Phase Behavior, Surface Tension, and Adsorption Measurement

“…2b, the ability to depress the cloud point follows the order Na + > Li + > Cs + . These findings agree with the results from other studies for pNIPAM (37) and are also analogous to the effect of anions on the CP of aqueous solutions of other polymers such as PEO and cellulose ethers (58,59).…”

Anionic surfactant aggregation with (Hydroxypropyl)cellulose in the presence of added salt

“…17, No. 5, 2006 hydrophobic modifications into polymers, as for example poly(sodium acrylate), 4 (hydroxyethyl)cellulose, [5][6][7] (hydroxypropyl)cellulose, 8 ethyl(hydroxyethyl)cellulose, 9,10 and poly(oxyethylene). 11 It was verified that hydrophobically modified polymers have improved properties in comparison to their unmodified analogues.…”

Temperature-dependent interactions between hydrophobically modified ethyl(hydroxyethyl)cellulose and methyl nanocellulose

“…The association between EHEC and surfactants has been determined with cloud point measurements. When the EHEC solution is heated it starts to separate at a certain temperature into polymer-rich and polymer-poor phases and becomes cloudy (Carlsson et al 1986;Joabsson et al 1998;Khuman et al 2014). It is known that the concentration and type of electrolyte affect the cloud point of EHEC.…”