Nanotecnologia

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Materials Chemistry and Physics 125 (2011) 709–717

Contents lists available at ScienceDirect

Materials Chemistry and Physics
journal homepage: www.elsevier.com/locate/matchemphys

CdSe quantum dots stabilized by carboxylic-functionalized PVA: Synthesis and
UV–vis spectroscopy characterization
Herman S. Mansur ∗ , Alexandra A.P. Mansur
Department of Metallurgical and MaterialsEngineering, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil

article

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Article history:
Received 6 July 2010
Received in revised form 6 September 2010
Accepted 25 September 2010
Keywords:
Polymers
Nanostructures
Semiconductors
Surface properties

abstract
Quantum dots (QDs) have drawn the attention of the research community in the last decade due to their
potentialuse in the fast developing area of nanotechnology. In this study, it is reported the synthesis and
characterization CdSe nanoparticles using acid-functionalized poly(vinyl alcohol) (PVA–COOH) polymer
as capping ligands via aqueous route at room temperature by methods of colloidal chemistry. Different
molar concentrations of PVA–COOH were investigated aiming at producing stable nanoparticlesusing
cadmium perchlorate and synthesized sodium selenosulfate. UV–vis spectroscopy was used to evaluate the kinetics and the relative stability of CdSe nanocrystals considering their size as-prepared and
subsequent growth. The QDs sizes were estimated by the “absorbance onset” from UV–vis spectroscopy
spectra, considering theoretical and empirical methods. The results have indicated that precursorsolution
of PVA–COOH at concentration of 1.0 mol L−1 was effective on stabilizing colloidal CdSe QDs in aqueous
suspension. Moreover, ultra-small CdSe nanocrystals were produced with calculated average particles
size under 2.0 nm, indicating they were in the so-called “quantum-size confinement range”. Hence, it was
developed a relatively simple colloidal route using a single-step method toproduce CdSe QDs water soluble and commercially available polymers that offers a window of opportunities to explore these novel
nanohybrid materials.
© 2010 Elsevier B.V. All rights reserved.

1. Introduction
New strategies for nanomaterials fabrication are of paramount
importance in the advancement of science and technology. Since
the early studies pioneered by Brus and co-workers [1]considerable
progress has been made in the synthesis of low-dimensional semiconductor structures. Physical, chemical, and electronic properties
of these zero-dimensional entities change dramatically because of
quantum effects. The semiconductor nanocrystals, often referred
to as “quantum dots” or “QDs”, are one of the most popular terms
in nano-science of the 21st century, essentially because of thealterations in the material as a result of the direct influence of
the ultra-small length scale on the energy band distribution in
the material [2]. These are promising nanomaterials based on
metal chalcogenides (i.e. MX, M = Cd, Pb, Hg and X = S, Se, Te)
concerning to the exploitation of their properties in all areas of
science, mainly associated with biomedical applications such asnanobiotechnology and nanomedicine [2,3]. The synthesis of QDs

∗ Corresponding author at: Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais, Av. Antônio Carlos, 6627 – Engenharia Bloco
2/3639 – Pampulha, 31.270-901 Belo Horizonte, MG, Brazil. Tel.: +55 31 3409 1843;
fax: +55 31 3409 1815.
E-mail address: hmansur@demet.ufmg.br (H.S. Mansur).
0254-0584/$ –see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.matchemphys.2010.09.068

was first described in 1982 by Efros [4] and Ekimov [5] who
grew nanocrystals of semiconductors in glass matrices. Since then,
several publications have reported the preparation of semiconductor nanoparticles by a variety of approaches, LB films [6,7],
SAM [8], zeolites [9], organic [10],...
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