Many people have noticed how, after visiting a coffee shop, their favorite sweater smells like roasted beans, and the plastic container retains the aroma of spices even after washing. The ability of surrounding objects to retain odors is not an accident, but a complex physical and chemical process based on diffusion And adsorption.
Porous structure of materials
The main reason why fabrics, wood and even some types of plastic “remember” odors lies in their structure. Most household materials have a huge number of microscopic pores. When odorous volatile compounds land on such a surface, they penetrate deep into the fibers or cavities. Natural fabricssuch as wool or cotton, are ideal sponges for gas molecules due to their high hygroscopicity.
Chemical affinity of molecules
Smells are specific chemicals. How strongly something smells depends on the type of molecules.
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Fat-soluble compounds: Most intense aromas (such as the smell of tobacco smoke or fried meat) are highly soluble in fat.
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Lipid layer: If there is a thin film of fat on the surface of an object or skin, it instantly binds odorous particles, “sticking” them to the wearer.
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Polymers: Plastic utensils often absorb food odors because plastic molecules are structurally related to organic food molecules, allowing them to literally mix at the molecular level.
Effect of humidity and temperature
The external environment plays the role of a catalyst. At high humidity the pores of the materials expand, and water droplets in the air retain aromatic compounds, making it easier for them to settle on objects. Temperature It also accelerates the movement of molecules: in a warm room the absorption process occurs several times faster than in a cold room.
Memory effect and desorption
The reverse process of absorption is called desorption. This is the gradual release of accumulated molecules back into the air. This is why old furniture or clothes can exude aromas accumulated over the years for a long time. The denser the structure of the material and the higher it is adhesion (the ability for molecules to stick), the more difficult it is to get rid of the intrusive plume without special chemical treatment or long-term ventilation.
The ability of objects to absorb volatile substances is a natural property of matter, determined by the structure of molecular bonds and the characteristics of the surface of objects.
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