Characterizing engineered nanomaterials: vendors offer an extensive portfolio of instruments to analyze material features on the nanoscale. But hurdles must be cleared before nanomaterials enter the manufacturing mainstream.
Most major materials companies and chemical companies are involved with nanomaterials, and almost every college with a materials program is involved in nanotechnology research and development. On the vendor side, instrument manufacturers such as PerkinElmer, Waltham, Mass., are making substantial commitments to understand the wide range and types of measurements needed to characterize nanomaterials.
To characterize a nanomaterial, it is necessary to know chemical and physical pararmeters including the size of the particle, its shape, surface characteristics, presence of surface coatings, and the presence of impurities.
At the nanoscale, analytical measurement challenges are considerable. For example, choosing to measure the elemental concentration of gold in a suspension by inductively coupled plasma-mass spectrosmetry (ICP-MS) as the only metric may be insufficient for the control of a manufacturing process. Complementary characterization of size, size distribution, or shape may be required.
Nanomaterials are typically defined by several characteristics, including particle size distribution, surface charge, surface area, shape, agglomeration, and structure. Acquisition of this information is typically accomplished through one or more analytical technique:
* Scanning electron microscopy (SEM)
* Transmission electron microscopy (TEM)
* Atomic force microscopy (AFM)
* Confocal microscopy (CFM)
* Dynamic light scattering (DLS)
* Field flow fractionation (FFF)
* Molecular gas adsorption (BET)
* Electrophoresis particle size
If a material is known and is reflective, ultraviolet/visible (UV/Vis) spectroscopy and fluorescence (FL) spectroscopy can be use for particle size identification. Fluorescence spectroscopy is also used for agglomeration studies.
Many analytical techniques can be used to determine nanoparticle concentration and composition; the correct method is determined by the material, coatings, and nano application.
For nanoparticle concentration, a researcher can choose one or more analytical techniques:
* Indutively coupled plasma and mass spectroscopy (ICP-MS)
* Liquid chromatography and mass spectroscopy (LC-MS)
* Ultraviolet/visible spectroscopy (UV/Vis)
* Fluorescence spectroscopy (FL)
For nanoparticle composition, analytical options include:
* Thermogravimetry (TGA)
* Differential scanning calorimetry (DSC)
* Dynamic mechanical analysis (DMA)
* Fourier transform infrared spectroscopy (FTIR)
* Thermogravimetry and mass spectroscopy (TGA-MS)
* Thermogravimetry, gas chromatography, and mass spectroscopy (TGAGC/MS)
* Raman spectroscopy
Impact of characterization on manufacturing
A saying among engineers goes: "If you can't measure it, you can't build it." Measurement is needed throughout the nanomaterial manufacturing process. This includes the source and quality of raw materials, control of the nanomaterial manufacturing process, end product formulation, incorporation in another product, and end use. Without material characterization (QC and QA), the end-product manufacturing process may be difficult to control and result in products that do not meet specification.
In addition, materials and hazardous waste disposal may be necessary at different points on the manufacturing chain. Because nanomaterials can enter the human body by dermal exposure, inhalation, and ingestion, nano-waste raises different concerns than bulk material waste. While there are no federal nanomaterial regulations to date, there is increasing review and concern--both within industry and in the environmental field--as to the fate of these materials.
--Andrew W. Salamon
Sr. Staff Scientist, PerkinElmer Inc.
Analytical Sciences & Laboratory Services
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|Comment:||Characterizing engineered nanomaterials: vendors offer an extensive portfolio of instruments to analyze material features on the nanoscale.|
|Author:||Salamon, Andrew W.|
|Publication:||R & D|
|Date:||Apr 1, 2011|
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