Issue 37, 2023

Salt induced micellization conduct in PEO–PPO–PEO-based block copolymers: a thermo-responsive approach

Abstract

The nanoscale self-assembly behavior in ethylene oxide (EO) and propylene oxide (PO)-based block copolymers (BCPs) commercially available as Pluronics®: L44 (PEO10–PPO23–PEO10) and F77 (PEO53–PPO34–PEO53) is put forth in aqueous solution and in the presence of sodium salts NaCl and Na2SO4. The moderate hydrophilicity of L44 is attributed to its low molecular weight PPO segment, while the high percentage of PEO content in F77 contributes to its extreme hydrophilicity. The impact of sodium salts (NaCl and Na2SO4) on the self-assembly is investigated to understand their influence and role in micellization, by employing various physicochemical techniques such as phase behavior conduct, calorimetry, tensiometry, scattering, and spectral analysis. The results indicate that at a low temperature range of 20–30 °C, Pluronics® solutions with a concentration of 10% w/v remain molecularly dissolved as individual units called unimers (Gaussian chain), which have a hydrodynamic size (Dh) of approximately 4–6 nm. Additionally, loose clusters of a few hundred nanometers in size are also observed. Though, at higher concentrations of BCPs and in the presence of salt or elevated temperatures, the examined micellar structures exhibit a higher degree of organization i.e., spherical or ellipsoidal in terms of size and shape. Also, the solubilization enhancement of a hydrophobic dye called orange OT within the examined micellar system is also undertaken using a spectral approach.

Graphical abstract: Salt induced micellization conduct in PEO–PPO–PEO-based block copolymers: a thermo-responsive approach

Article information

Article type
Paper
Submitted
08 Jul 2023
Accepted
12 Sep 2023
First published
19 Sep 2023

Soft Matter, 2023,19, 7227-7244

Salt induced micellization conduct in PEO–PPO–PEO-based block copolymers: a thermo-responsive approach

N. Tripathi, D. Ray, V. K. Aswal, K. Kuperkar and P. Bahadur, Soft Matter, 2023, 19, 7227 DOI: 10.1039/D3SM00896G

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