What Causes the Anomalous Aggregation in Pluronic Aqueous Solutions?

Published

May 28, 2018

Author(s)

Kuo-Chih Shih, Zhiqiang Shen, Ying Li, Martin Kroger, Shing-Yun Chang, Yun Liu, Mu-Ping Nieh, Hsi-Mei Lai

Abstract

Pluronic (PL) block copolymers has been widely used as delivery carriers, molecular templates for porous media, process additive of affecting rheological behavior. Unlike most surfactant systems, where unimer transforms into micelle with increased surfactant concentration, anomalous large PL aggregates below the critical micelle concentration (CMC) were found throughout four PL types (F108, F127, F88 and P84). We characterized their structures using dynamic light scattering and small-angle X-ray/neutron scattering. The formation rate of these aggregates is promoted through vigorous shear. Molecular dynamic simulations suggest that the exposed PPO segments promote the shear-induced formation of large clusters in spite of slow process. Addition of acid and base (e.g citric acid, acetic acid, HCl and NaOH) in F108 solution significantly suppressed the aggregate formation up to 20 days due to the repulsion force from the attached H₃O⁺ molecules on PEO segment and the reduction of CMC through the salting out effect, respectively.

Citation

Soft Matter

Volume

14

Pub Type

Journals

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Keywords

Poloxamer, Dynamic Light Scattering, Small-Angle Neutron Scattering, Small-Angle X-ray Scattering, Slow Mode, Micelles, Unimer, Aggregates

Citation

Shih, K. , Shen, Z. , Li, Y. , Kroger, M. , Chang, S. , Liu, Y. , Nieh, M. and Lai, H. (2018), What Causes the Anomalous Aggregation in Pluronic Aqueous Solutions?, Soft Matter, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924598 (Accessed December 26, 2024)