Issue 33, 2024

Temperature-dependent yield stress and wall slip behaviour of thermoresponsive Pluronic F127 hydrogels

Abstract

This study explores the temperature-dependent dynamic yield stress of a triblock thermoresponsive polymer, Pluronic F127, with chemical structure (PEO)100(PPO)65(PEO)100, during the sol–gel transition. The yield stress can be defined as static, dynamic, or elastic, depending on the experimental protocol. We examine the dynamic yield stress estimation for this study, which usually entails utilizing non-Newtonian models like the Herschel–Bulkley (HB) or Bingham models to extrapolate the flow curve (shear rate against shear stress). Initially, we determine the yield stress using the HB model. However, apparent wall slip makes it difficult to calculate yield stress using conventional methods, which could lead to underestimates. To validate the existence of apparent wall slip in our trials, we carry out meticulous experiments in a range of rheometric geometries. To determine the true yield stress corrected for slip, we first use the traditional Mooney method, which requires labor-intensive steps and large sample sizes over various gaps in the parallel plate (PP) design. To overcome these drawbacks, we use a different strategy. We modify the Windhab model equation by adding slip boundary conditions to the HB equation, which allowed us to calculate the slip yield stress in addition to the true yield stress. In contrast to other typical thermoresponsive polymers like poly(N-isopropyl acrylamide) (PNIPAM), our findings demonstrate that PF127's yield stress obeys the Boltzmann equation and increases with temperature.

Graphical abstract: Temperature-dependent yield stress and wall slip behaviour of thermoresponsive Pluronic F127 hydrogels

Supplementary files

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Article information

Article type
Paper
Submitted
03 Jūl. 2024
Accepted
20 Jūl. 2024
First published
29 Jūl. 2024
This article is Open Access
Creative Commons BY license

RSC Adv., 2024,14, 23772-23784

Temperature-dependent yield stress and wall slip behaviour of thermoresponsive Pluronic F127 hydrogels

S. N. Sangitra and R. K. Pujala, RSC Adv., 2024, 14, 23772 DOI: 10.1039/D4RA04825C

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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