Aggregation in aqueous media of tri-block copolymers tuned by the molecular selectivity of cyclodextrins
The water + cyclodextrin + poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) mixtures have been investigated to explore the temperature effect on the aggregation of the copolymer in the presence of cyclodextrins (CDs). The CDs with different cavity sizes were chosen because they may include either the hydrophilic poly(ethylene oxides) block or both kinds of blocks. The differential scanning calorimetry and viscosity experiments straightforwardly evidenced that the critical micellar temperature is shifted to larger values by adding a CD which is able to include the middle poly(propylene oxide) block while it is not influenced by the presence of CD which is selective to the poly(ethylene oxide) block. The enthalpy of aggregation decreases upon the CD addition for all the investigated systems.
KeywordsCritical micellar temperature Enthalpy of aggregation F68 F88 F108 Hydroxypropyl-α-cyclodextrin Hydroxypropyl-β-cyclodextrin Pseudopolyrotaxanes
The work was financially supported by the University of Palermo.
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