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Faculté des Sciences
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Scalable continuous flow technology for the preparation of high-value added nanoparticles

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Bianchi, Pauline ULiège
Promotor(s) : Monbaliu, Jean-Christophe ULiège
Date of defense : 21-Feb-2020 • Permalink : http://hdl.handle.net/2268.2/9792
Details
Title : Scalable continuous flow technology for the preparation of high-value added nanoparticles
Author : Bianchi, Pauline ULiège
Date of defense  : 21-Feb-2020
Advisor(s) : Monbaliu, Jean-Christophe ULiège
Committee's member(s) : Eppe, Gauthier ULiège
Dreesen, Laurent ULiège
Gimmler, Christoph 
Language : English
Keywords : [en] continuous flow technology
[en] nanoparticles
[en] quantum dots
Discipline(s) : Physical, chemical, mathematical & earth Sciences > Chemistry
Research unit : Center for Integrated Technology and Organic Synthesis
Institution(s) : Université de Liège, Liège, Belgique
Degree: Master en sciences chimiques, à finalité approfondie
Faculty: Master thesis of the Faculté des Sciences

Abstract

[en] The nanotechnology field has found a wide range of utilities in our daily life and has deeply impacted the way of conceiving the world. Nanoparticles are inherently endowed with a high surface-to-volume ratio and possess remarkable size- and shape-dependent properties. The protocols for the preparation of nanoparticles are therefore really demanding for the accurate tailoring of size, shape and size dispersion control. The emergence of continuous flow technology and its application to the nanotechnology field has greatly improved the quality of such protocols by enabling accurate control of the local parameters, homogeneous mixing, fast thermal and mass transfers, convenient and fast monitoring, high reproducibility and fast lab-to-market transitions. Within this context, this research program aimed at the development of novel, potentially scalable, flow processes for the preparation of two types of nanoparticles, namely, cadmium selenide quantum dots and gold nanoparticles. The assets of continuous flow manufacturing were exploited to afford robust protocols aiming at potentially industrial productions. Their development was also thought in the context of sustainability. Aqueous protocols were developed to ease the implementation of further biological functionalizations.

The first section of this work is devoted to the development of a novel water-soluble selenide precursor for the continuous flow synthesis of cadmium selenide quantum dots. The optimization of the synthesis of the novel Se precursor was first carried out before taking care of the quantum dots production. Different process parameters such as pH, ligand concentration, temperature and selenide-to-cadmium ratio, were first optimized under batch conditions and compared to those obtained in fluidic reactors. The preliminary observations (slow kinetics) led to a significant modification of the process with the segregation of the nucleation step from the growth process in two independent concatenated flow modules. Small nuclei were obtained rapidly at elevated temperatures (> 200 °C), moderate pressure (17 to 25 bar) and short residence times (< 10 s). The competing surface fluorescence was not completely suppressed. The optimization of this two-step protocol is still undergoing to afford a size-tunable production. Due to the nature of the ligand, CdSexSy alloys capped by thiolates were actually obtained.

The second part of this work is dedicated to the development of a scalable photochemical flow process towards spherical gold nanoparticles. This protocol emerged as a potential and robust alternative to the well-known high-temperature citrate reduction. In this protocol, an unprecedented water-soluble acylphosphinate photoinitiator was identified for the preparation of gold nanoparticles. Upon exposure with UV irradiation, it underwent a Norrish type I cleavage and produced radicals able to reduce chloroauric acid into Au(0), eventually leading to the formation of nanoparticles. One of the main breakthroughs of this research program was the identification of robust and reproducible conditions that precluded the formation of a gold coating on the internal surfaces of the reactor. Such an issue is described in the literature and is seen as a major obstacle for the development of scalable and robust processes towards gold nanoparticles. The optimized protocol included the addition of external stabilizing ligands as well as finely tuned experimental parameters. Such ligands were also used to ensure stability for the nanoparticles over time. pH fluctuations were limited by working in a phosphate buffer. The implementation of an in-line UV spectrometer enabled real-time process monitoring for the optimization at the lab-scale. The optimized conditions were successfully transposed to pilot and production scales for the very first time of the history of continuous flow gold nanoparticle synthesis. A productivity of 65 g/day for a residence time as short as 10 s was achieved.

This work opens new perspectives for the development of robust protocols towards high-value added nanoparticles and highlights the potential assets of continuous flow technology in the nanotechnology field.


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Author

  • Bianchi, Pauline ULiège Université de Liège > Master en sc. chimiques, à fin.

Promotor(s)

Committee's member(s)

  • Eppe, Gauthier ULiège Université de Liège - ULiège > Département de chimie (sciences) > Chimie analytique inorganique
    ORBi View his publications on ORBi
  • Dreesen, Laurent ULiège Université de Liège - ULiège > Département de physique > Biophotonique
    ORBi View his publications on ORBi
  • Gimmler, Christoph Fraunhofer IAP > Zentrum für Angewandte Nanotechnologie CAN > Nanoskalige Energie- und Strukturmaterialien
  • Total number of views 44
  • Total number of downloads 14










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