Image Caption: A graphical representation illustrates microgel particles (colored in green) orienting themselves within a fluid medium, their associated ion clouds (depicted in red) appearing on their exterior. Image Courtesy: Urs Gasser
Researchers from the Paul Scherrer Institute (PSI) and the University of Barcelona have successfully demystified the perplexing attributes of microgels. Utilizing neutron beam experimentation, they have pushed the boundaries of this analytical method. The findings offer a wealth of new avenues for exploration in material science and pharmaceutical research.
Microscopic particles or droplets finely dispersed in a solvent flow through our veins, contribute pigmentation to our walls, or enhance the flavor of milk. These dispersed particles collectively create a colloid. While the physics of colloids that contain hard particles, like the pigments in emulsion paint, are fairly understood, colloids with soft particles like hemoglobin or fat droplets in milk present unexpected phenomena.
About 15 years ago, an experiment revealed a surprising characteristic of soft polymer-based particles, known as microgels. These particles undergo a rapid reduction in size when their concentration in a solvent exceeds a certain point. Intriguingly, even particles not in physical contact shrink to match the dimensions of their smaller counterparts.
The question that baffled scientists was how one gel particle could discern the size of its neighboring particle without any physical contact. Was there a sort of “communication” between these microgels?
2016 Hypothesis Validated
Urs Gasser, who has spent a decade examining the unique contraction of microgels in colloids, refutes any such idea. In a 2016 paper, his research team provided an explanation for this behavior. Simply put, the polymer particles are made of extended carbon chains carrying a faint negative charge at one end. These chains coalesce into a sphere known as a microgel, resembling a sponge-like ball of yarn.
Within this three-dimensional labyrinth, negative charges attract positive ions present in the liquid, termed as counterions. These counterions cluster around the negatively charged elements within the sphere, forming a positively charged cloud surrounding the microgel. When microgels approach each other, their ion clouds intersect, resulting in increased internal liquid pressure, which leads to the contraction of the microgel particles until a new equilibrium is achieved.
Previously, however, definitive experimental evidence for the counterion cloud was lacking. Working with his doctoral students Boyang Zhou and Alberto Fernandez-Nieves from the University of Barcelona, Gasser has now supplied this critical evidence, thereby corroborating the 2016 theory. Their results have been documented in the scientific journal Nature Communications.
Significance of SINQ Neutron Source
The breakthrough became possible through the employment of neutrons from PSI’s spallation source, SINQ. Coupled with an experimental methodology, this enabled the researchers to visualize the sparsely populated cloud of counterions, which make up a mere one percent of a microgel’s mass. Gasser, Zhou, and Fernandez-Nieves used two sample colloids, one with sodium ions and another with ammonium ions, to differentiate the neutron scattering patterns, making the elusive ion clouds visible.
Diverse Applications in Multiple Industries
Understanding the behavior of soft microgels in colloids opens the door for a myriad of applications. In the petroleum sector, these particles are injected into subterranean reservoirs to modify the oil’s viscosity, aiding extraction processes. In the cosmetic industry, they lend the requisite texture to creams.
Additionally, the prospects for ‘smart’ microgels are vast. These particles could be engineered to release medicine in reaction to stomach acids or serve as temperature or pressure sensors in confined fluid channels. According to Urs Gasser, the possibilities are endless.
Reference: “Measuring the counterion cloud of soft microgels using SANS with contrast variation” by Boyang Zhou, Urs Gasser, and Alberto Fernandez-Nieves, published on 7 July 2023 in Nature Communications.
DOI: 10.1038/s41467-023-39378-5
Table of Contents
Frequently Asked Questions (FAQs) about Microgels Scientific Breakthrough
What is the main focus of the research conducted by scientists from PSI and the University of Barcelona?
The main focus of the research is to understand the mysterious behavior of microgels, particularly how they shrink when their concentration in a solvent exceeds a certain level. The study employed neutron beam experimentation and has implications for both material science and pharmaceutical research.
Who is Urs Gasser and what role does he play in this research?
Urs Gasser is a physicist who has been studying the behavior of microgels in colloids for a decade. He was part of the team that initially proposed a hypothesis in 2016 to explain the strange shrinking behavior of microgels. In the current study, he worked with doctoral students to provide experimental evidence supporting this hypothesis.
What are colloids and how do microgels fit into this category?
Colloids are mixtures where tiny particles or droplets are finely distributed in a solvent. Microgels are a specific type of soft particle in colloids made from polymers. Unlike hard particles, such as pigments in paint, microgels have surprising attributes like shrinking when their concentration in a solvent increases beyond a certain point.
What was the groundbreaking experimental technique used in this study?
The groundbreaking technique employed was neutron beam experimentation using PSI’s spallation source, SINQ. The team used an innovative method to visualize the sparsely populated cloud of counterions, which were otherwise difficult to detect due to their minimal mass in a microgel.
What are some potential applications for this research in material science and pharmaceuticals?
Understanding the behavior of microgels in colloids offers new avenues for their use in a variety of applications. In the petroleum industry, these particles can be used to adjust the oil’s viscosity in subterranean reservoirs. In cosmetics, they can lend the desired texture to creams. Additionally, ‘smart’ microgels can be engineered to serve as medication delivery systems or as sensors in confined fluid channels.
What is the significance of the counterion cloud?
The counterion cloud is a positively charged cluster of ions that forms around the negatively charged elements within a microgel. This cloud is crucial for understanding why microgels shrink when they come close to each other. The overlapping of these counterion clouds leads to increased internal liquid pressure, causing the microgel particles to contract.
What was the publication where the research findings were published?
The research findings were published in the scientific journal Nature Communications, under the title “Measuring the counterion cloud of soft microgels using SANS with contrast variation,” authored by Boyang Zhou, Urs Gasser, and Alberto Fernandez-Nieves, on 7 July 2023.
More about Microgels Scientific Breakthrough
- Nature Communications Journal Article
- Paul Scherrer Institute (PSI)
- University of Barcelona Research Department
- Overview of Colloid Science
- Introduction to Neutron Beam Experimentation
- Pharmaceutical Research Implications of Microgels
- Material Science and Microgel Applications
- Urs Gasser’s Previous Research on Microgels
10 comments
Neutron beam experimentation? Sounds like sci-fi. but it’s real, and it’s here. mind-blowing.
anyone know where I can read the full article? Nature Communications, but is it free?
So they managed to prove their own hypothesis. Convenient, but I guess that’s how science works sometimes.
im super impressed with how they managed to prove the hypothesis from 2016. science, you never cease to amaze me!
Wow, never knew microgels were so fascinating. Who’d have thought they had these kinda characteristics, right?
hope they consider the environmental impact before going full throttle on these applications. Just sayin’.
Pharmaceutical applications, huh? Color me interested. This could be a game changer in drug delivery systems.
So, we can use microgels to adjust oil viscosity in reservoirs, huh? gotta look into this for sure.
If they can make creams better, I’m all ears. Or should I say, all skin? lol
Urs Gasser’s been at it for a decade, and it finally paid off! That’s some dedication, man.