Effect of ionic liquid on diffusion in P123 gel: fluorescence correlation spectroscopy

Area of Science:

• Polymer science
• Materials science
• Physical chemistry

Background:

• Triblock copolymers like Pluronic P123 form gels with unique properties.
• Understanding molecular diffusion in these gels is crucial for applications.
• Room-temperature ionic liquids (RTILs) are versatile solvents with tunable properties.

Purpose of the Study:

• To investigate the effect of RTILs on the diffusion of fluorescent dyes in a Pluronic P123 gel.
• To determine how RTILs influence the local viscosity and structure of the gel.
• To elucidate the interaction mechanism between RTILs and the triblock copolymer gel.

Main Methods:

• Fluorescence Correlation Spectroscopy (FCS) was used to measure diffusion coefficients.
• Field-Emission Scanning Electron Microscopy (FESEM) was employed to analyze gel morphology.
• Three fluorescent dyes (DCM, C480, C343) with varying hydrophobicity were utilized.

Main Results:

• RTILs increased the diffusion coefficients of all tested dyes in the P123 gel.
• The effective local viscosity of the gel core decreased upon RTIL addition.
• FESEM confirmed that RTILs did not alter the macroscopic structure of the P123 gel.
• RTILs were found to modify micellar aggregate size and penetrate the gel core.

Conclusions:

• RTILs act as viscosity reducers in Pluronic P123 gels.
• The interaction of RTILs with the gel involves structural modification at the nanoscale.
• This study provides insights into the use of RTILs for tuning polymer gel properties.