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Introduction
Particles play a fundamental role in shaping our world and have a profound impact on society in ways that often go unnoticed. Whether it’s the control of pollutants in the atmosphere, the development of advanced pharmaceuticals, the optimization of food production processes, or the creation of innovative materials for construction and electronics, the size of particles can significantly influence product quality, environmental sustainability, and human health.
In this era of rapid technological advancement and increasing environmental awareness, the study and manipulation of particle sizes have become central to addressing some of the most pressing challenges facing our society.
Particles have a profound impact on society, particularly within the fields of materials science and environmental sciences. They are worthy of proper characterization as evidenced by the plethora of scientific technologies to measure and characterize particles. But before we can judge the suitability of the various scientific methodologies to characterize particles, we first must have an understanding of what particles are.
Definition of a particle
While particles come in many shapes and sizes, all particles have in common that they can be described as small, localized, objects that can be characterized with physical and chemical properties such as mass, volume, and composition. With such a broad definition of particles, it is no surprise that different disciplines approach particles differently. Here we hope to clarify expectations when material scientists refer to particles.
However, the nature and behavior of particles can vary greatly based on their size, composition, as well as the overall environment the particles are in.
Particle sizes
The smallest particles in the universe are subatomic particles, which are the building blocks of matter. The most well-known subatomic particles include quarks, bosons, and electrons. These particles are the smallest known constituents of matter and play a fundamental role in the structure and behavior of the universe at the quantum level.
At the atomic level, we encounter individual atoms characterized by a nucleus composed of protons and neutrons, encircled by electrons in specific energy levels or orbitals.
On the other hand, molecular particles are formed when two or more atoms bond together through chemical interactions, creating molecules. Molecules exhibit distinct properties that differ from those of their constituent atoms, making them the building blocks of compounds and essential for understanding the chemistry of substances.
Investigating these atomic and molecular particles is crucial in fields such as chemistry, physics, and materials science, enabling us to unravel the mysteries of the microscopic world and apply this knowledge to various technological advancements.
The above particles are often the domain of particle physics whereas material scientists often restrict themselves to particles in the nanometer and larger size ranges. Due to their ability to travel large distances and settle on surfaces, e.g. pollen, micrometer-sized particles are frequently studied.
Colloidal particles represent another intriguing category of particles that exist in a size range between atomic and bulk materials. These particles, often found in colloidal suspensions or colloids, are typically composed of small clusters of atoms or molecules dispersed in a solvent medium. What distinguishes colloidal particles is their ability to exhibit unique and often unexpected properties due to their intermediate size.
They can interact with external forces such as Brownian motion and exhibit distinctive optical, electrical, and mechanical behaviors, The study of colloidal particles is particularly crucial in fields like chemistry, biology, and materials science, where they find use in diverse applications, including drug delivery systems, food science, and nanotechnology.
Particle Sizing
Today several approaches are available to size particles, each with their advantages and limitations. In addition to traditional methods such as sieve analysis and sedimentation, modern techniques including laser diffraction, dynamic light scattering (DLS), and microscopy are available to determine the size and/or morphology of particles.
Transmission electron microscopes and scanning electron microscopes are some of the most powerful analytical techniques to study particles. Not only because of the high magnifications but also because many electron microscopes can be equipped with various detectors to provide insight into local chemistries.
Particle Chemistry
While control of particle size and morphology is critical for many applications, the chemistry of individual particles is often required to confirm particle origin. Depending on the particle size, various analytical techniques are available to determine particle chemistry. A potential pitfall in selecting the appropriate analytical technique is that in some cases chemistry and morphology at the interface between particles or particle and matrix determines material properties. For example, chemical reactions such as corrosion are surface sensitive.
Summary
In conclusion, this application note provides a definition of particle for material scientists as well as introduces various analytical techniques to size particles. Lastly, analytical techniques were identified to determine the chemistries of individual particles. However, in selecting the proper analytical techniques it should be noted that often critical processes occur on the interface between particle and matrix material.