Biomedical Engineering Reference
In-Depth Information
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As-Produced
Intrinsic Physico-Chemical
Properties and Appropriate
Characterization Tools
Emilia Izak-Nau and Matthias Voetz
CONTENTS
1.1 Introduction ...................................................................................................... 3
1.2 Particle Size/Size Distribution .......................................................................... 7
1.3 Aggregation and Agglomeration State ........................................................... 10
1.4 Shape ............................................................................................................... 11
1.5 Surface Area ................................................................................................... 11
1.6 Composition .................................................................................................... 12
1.7 Surface Chemistry .......................................................................................... 13
1.8 Surface Charge ............................................................................................... 15
1.9 Solubility/Dispersibility .................................................................................. 16
1.10 Control of Properties by Surface Functionalization ....................................... 16
Acknowledgments .................................................................................................... 19
References ................................................................................................................ 19
1.1 INTRODUCTION
It is well known that nanomaterials possess different chemical and physical proper-
ties than bulk materials of identical composition. When the particle size decreases to
nanoscale, the fundamental characteristics of the material often changes, resulting
in completely new properties. For instance, previously colorful materials become
transparent, insulators become conductive, or the melting point of nanoparticles evi-
dently drops when their size is below 100 nm (Nalwa 2004; Wang 2000). When
the particle size decreases, the proportion of atoms found at the surface relative to
the atoms in the interior of the particle increases. Thus, nano-objects have a much
larger surface area per unit mass compared with bigger particles. The increase in the
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