A Way to Predict Gold Nanoparticles/Polymer Hybrid Microgel Agglomeration Based on Rheological Studies.

Coro Echeverría,Carmen Mijangos

doi:10.3390/nano9101499

Abstract

In this work, a detailed rheological study of hybrid poly(acrylamide-co-acrylic acid) P(AAm-co-AAc) aqueous microgel dispersions is performed. Our intention is to understand how the presence of gold nanoparticles, AuNP, embedded within the microgel matrix, affects the viscoelastic properties, the colloidal gel structure formation, and the structure recovery after cessation of the deformation of the aqueous microgel dispersions. Frequency sweep experiments confirmed that hybrid microgel dispersions present a gel-like behavior and that the presence of AuNP content within microgel matrix contributes to the elasticity of the microgel dispersions. Strain sweep test confirmed that hybrid microgels aqueous dispersion also form colloidal gel structures that break upon deformation but that can be recovered when the deformation decreases. The fractal analysis performed to hybrid microgels, by applying Shih et al. and Wu and Morbidelli’s scaling theories, evidenced that AuNP significantly affects the colloidal gel structure configuration ending up with the formation of agglomerates or microgel clusters with closer structures in comparison to the reference P(AAm-co-AAc) aqueous microgel dispersions.

Highlights

Among all colloidal systems, the sub micrometer-sized hydrogel particles are of special interest [1,2]
Strain sweep test confirmed that hybrid microgels aqueous dispersion form colloidal gel structures that break upon deformation but that can be recovered when the deformation decreases
In the present work we have studied how hybrid microgel dispersions behave under strain and evaluated the influence of AuNP embedded in the microgel matrix

Summary

Introduction

The sub micrometer-sized hydrogel (microgels) particles are of special interest [1,2]. We first developed poly(acrylamide-co-acrylic acid) microgels featured with the ability to swell upon heating, showing a positive thermosensitivity and an upper critical solution temperature-like (UCST) volume phase transition temperature [17,18]. This thermo-responsiveness derived from the presence of acrylic acid that forms hydrogen bonds with acrylamide. This study outlined their macroscopic elasticity showing that the material behaves as a colloidal gel [17,18]

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