Synthesis of Colloidal Au Nanoparticles through Ultrasonic Spray Pyrolysis and Their Use in the Preparation of Polyacrylate-AuNPs' Composites.

Doris Golub,Andrej Ivanič,Peter Majerič,Rebeka Rudolf,Ivan Anžel,Hanuma Reddy Tiyyagura

doi:10.3390/ma12223775

Abstract

Colloidal gold nanoparticles (AuNPs) were prepared from two different liquid precursors (gold (III) acetate and gold (III) chloride), using the Ultrasonic Spray Pyrolysis (USP) process. The STEM characterisation showed that the AuNPs from gold chloride are spherical, with average diameters of 57.2 and 69.4 nm, while the AuNPs from gold acetate are ellipsoidal, with average diameters of 84.2 and 134.3 nm, according to Dynamic Light Scattering (DLS) measurements. UV/VIS spectroscopy revealed the maximum absorbance band of AuNPs between 532 and 560 nm, which indicates a stable state. Colloidal AuNPs were used as starting material and were mixed together with acrylic acid (AA) and acrylamide (Am) for the free radical polymerization of polyacrylate-AuNPs’ composites, with the purpose of using them for temporary cavity fillings in the dental industry. SEM characterisation of polyacrylate-AuNPs’ composites revealed a uniform distribution of AuNPs through the polymer matrix, revealing that the AuNPs remained stable during the polymerization process. The density measurements revealed that colloidal AuNPs increase the densities of the prepared polyacrylate-AuNPs’ composites; the densities were increased up to 40% in comparison with the densities of the control samples. A compressive test showed that polyacrylate-AuNPs’ composites exhibited lower compressive strength compared to the control samples, while their toughness increased. At 50% compression deformation some of the samples fracture, suggesting that incorporation of colloidal AuNPs do not improve their compressive strength, but increase their toughness significantly. This increased toughness is the measured property which makes prepared polyacrylate-AuNPs potentially useful in dentistry.

Highlights

Over the past two decades, metal nanoparticles, especially gold nanoparticles (AuNPs), have attracted a lot of attention from the scientific community due to their specific and unique chemical, physical, photochemical, optical and electronic properties, which differ from the properties of materials in their bulk state [1]
The increased toughness implies that the incorporation of colloidal AuNPs greatly improved energy absorption for this material system, which is a major feature composites for their use in dental applications
We reported the successful synthesis of colloidal AuNPs from two different gold metal salt precursors, gold (III) chloride and gold (III) acetate, respectively, using modified Ultrasonic Spray Pyrolysis (USP) and their use in the preparation of polyacrylate-AuNPscomposites

Summary

Introduction

Over the past two decades, metal nanoparticles, especially gold nanoparticles (AuNPs), have attracted a lot of attention from the scientific community due to their specific and unique chemical, physical, photochemical, optical and electronic properties, which differ from the properties of materials in their bulk state [1]. The most common methods for the top-down approach are mechanical grinding and ball-milling, chemical etching, nanolithography and laser ablation [28,29,40,41]. All of these methods are suitable for the production of small quantities of nanoparticles, whose sizes and shapes are dependent on the used batch

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