How Microscopic Imperfections Transform Our Macroscopic World
August 27-31, 2018 • Lublin, Poland
Imagine running your fingers over a seemingly smooth piece of glass. To your touch, it feels perfectly uniform, but at the molecular level, you're actually traversing a complex landscape of peaks, valleys, and chemical variations that influence everything from how water beads on its surface to how effectively it repels dust. This invisible world of surface heterogeneity—the microscopic irregularities and chemical variations on material surfaces—may escape our naked eye observation, yet it fundamentally governs processes critical to addressing global challenges in energy, environmental remediation, and advanced manufacturing.
The scientific community dedicated to understanding these fascinating surface properties gathered in Lublin, Poland, from August 27-31, 2018, for a landmark event: the tenth International Symposium on Effects of Surface Heterogeneity in Adsorption, Catalysis and related Phenomena (ISSHAC-10). This jubilee symposium brought together over 130 leading researchers from 18 countries to share breakthroughs in how we understand, characterize, and harness surface heterogeneity for technological advancement 1 . Their work reveals that what we often consider "imperfections" in materials are actually gateways to unprecedented functionality.
Surface heterogeneity refers to both the geometric and chemical variations that occur across solid surfaces at atomic and molecular scales. These variations create a landscape of different binding sites with varying affinities for other molecules—a concept that revolutionizes how we understand interactions between materials and their environments.
Occurs when different chemical functional groups or elements are present on a surface. Imagine a patchwork of hydrophilic (water-attracting) and hydrophobic (water-repelling) areas on a single material, each behaving differently when exposed to moisture.
Involves physical variations in surface topography—pores, steps, ridges, and valleys at the nanoscale that create unique microenvironments for molecular interactions.
These seemingly minor variations have major consequences. They determine how effectively catalysts accelerate chemical reactions, how well adsorbents capture greenhouse gases, how efficiently filtration systems remove contaminants, and how precisely medical implants integrate with biological tissues 1 5 .
The ISSHAC symposium series began in 1992 as the brainchild of Professor Wladek Rudziński (Maria Curie-Skłodowska University, Poland) and Professor Bohdan Wojciechowski (Queen's University, Canada). What started as a gathering of "several dozen scientists" in the picturesque Polish town of Kazimierz Dolny has evolved into a premier international scientific event that rotates through Poland's most beautiful cities every three years 1 .
First ISSHAC symposium in Kazimierz Dolny with several dozen scientists
Jubilee ISSHAC-10 in Lublin with over 130 researchers from 18 countries
Planned ISSHAC-12 to continue the tradition of scientific exchange
The 2018 jubilee symposium in Lublin—where the original idea was conceived—featured an impressive 58 oral presentations and 117 poster presentations, reflecting the growing importance and diversity of this field 1 . The tradition of publishing selected papers in prestigious journals like Adsorption (which dedicated its entire Volume 25, Issue 3 to ISSHAC-10研究成果) ensures these advancements reach the global scientific community 6 .
The art of selective capture
Molecular interactions driving global industries
Advanced applications beyond traditional fields
Adsorption—the process where atoms or molecules adhere to a surface—is profoundly influenced by surface heterogeneity. Different binding sites on a heterogeneous surface can selectively capture specific molecules from complex mixtures, a principle fundamental to numerous technologies:
The symposium featured cutting-edge research on designing materials with tailored heterogeneities to enhance these adsorption processes 5 .
Heterogeneous catalysis—where the catalyst exists in a different phase from the reactants—accounts for approximately 90% of all industrial chemical processes. Surface heterogeneity creates active sites with varying catalytic properties, influencing both the speed and selectivity of reactions:
Designing catalysts that efficiently convert renewable resources into fuels
Developing more selective catalysts that reduce waste byproducts
Creating catalytic converters that operate effectively under real-world conditions
One particularly illuminating study presented at ISSHAC-10 and later published in the special issue of Adsorption demonstrates how scientists tackle the challenge of characterizing surface modifications that are invisible to conventional imaging techniques. Researchers from AGH University of Science and Technology investigated how hydrophobization—making materials water-repellent—affects the fine structure of limestone materials 8 .
The research team employed a sophisticated approach using gas adsorption techniques to map the changes in limestone surfaces after treatment with various hydrophobic agents.
The research yielded fascinating insights into how surface treatments alter material properties in ways invisible to conventional microscopy:
| Sample Treatment | Specific Surface Area (m²/g) | Pore Volume (cm³/g) | Hydrophobicity Index |
|---|---|---|---|
| Raw limestone | 5.82 | 0.031 | 0 (reference) |
| Stearic acid | 4.91 (-16%) | 0.026 (-16%) | 0.87 |
| Silicone | 4.23 (-27%) | 0.022 (-29%) | 0.92 |
| Bituminous | 3.97 (-32%) | 0.020 (-35%) | 0.95 |
The data revealed that all treatments reduced both specific surface area and pore volume—indicating that hydrophobic agents partially block access to the porous structure. More significantly, the research demonstrated that the degree of reduction correlated directly with improved hydrophobicity 8 .
Perhaps the most important finding was that both nitrogen and krypton adsorption told the same story about the effectiveness of the different modifiers, despite their different chemical properties. This consistency across measurement techniques provides scientists with a reliable toolset for evaluating surface modifications.
| Measurement Property | Nitrogen | Krypton | Correlation |
|---|---|---|---|
| Surface area reduction | 16-32% | 15-30% | Excellent |
| Pore volume reduction | 16-35% | 18-34% | Excellent |
| Relative ranking of modifiers | Consistent | Consistent | Identical |
Surface heterogeneity research employs specialized materials and reagents designed to probe and manipulate molecular interactions. Here are some key components of the surface scientist's toolkit:
| Reagent/Material | Primary Function | Research Applications |
|---|---|---|
| Nitrogen gas | Standard adsorbate for surface characterization | Measuring surface area, pore size distribution, and adsorption energetics |
| Krypton gas | Alternative adsorbate for low-surface-area materials | Characterizing poorly-adsorbing materials, ultra-precise surface measurements |
| Hydrophobic agents (stearic acid, silanes) | Modify surface chemistry | Creating water-repellent surfaces, studying self-assembly phenomena |
| Probe molecules (CO₂, H₂O, various organics) | Assess specific surface interactions | Mapping chemical heterogeneity, evaluating catalytic active sites |
| Porous framework materials (zeolites, MOFs) | Highly defined yet heterogeneous surfaces | Designing tailored separation systems, catalyst supports, gas storage materials |
The research presented at ISSHAC-10 demonstrates that surface heterogeneity is far from a scientific curiosity—it is a fundamental materials property that we are learning to measure with increasing precision and manipulate with growing sophistication. As symposium organizers noted, this understanding "plays a key role in a wide range of physical processes including adsorption, catalysis, separation, gas storage, hydrophobic surfaces, electrochemistry, and many others" 1 .
As the ISSHAC tradition continues—with ISSHAC-12 already planned for September 2025 in Lublin —we can anticipate ever deeper understanding of how the molecular landscape of surfaces shapes our macroscopic world.
This research reminds us that sometimes, perfection lies not in flawless uniformity, but in strategically designed diversity—a lesson from surface science that extends far beyond the laboratory.