Sensitive Matter: Foams, Gels, Liquid Crystals, and Other Miraclesby Michel Mitov
Life would not exist without sensitive, or soft, matter. Red blood globules, lung fluid, and membranes depend on it, as do industrial emulsions, gels, plastics, liquid crystals, and granular materials. Physicist Michel Mitov ranges from the miracle of mayonnaise to the liquefaction of dry blood in this fascinating introduction.See more details below
Life would not exist without sensitive, or soft, matter. Red blood globules, lung fluid, and membranes depend on it, as do industrial emulsions, gels, plastics, liquid crystals, and granular materials. Physicist Michel Mitov ranges from the miracle of mayonnaise to the liquefaction of dry blood in this fascinating introduction.
A slim, engaging volume that mixes mini lessons on such subjects as thixotropic fluidsthink house paint and ballpoint pen ink, both of which flow when someone applies pressure to them but gel when left alonewith anecdotes from the author's adventurous life...Readers come away from the book with a renewed appreciation for the complexity of such everyday substances as champagne, rubber and toothpaste.
Sandra Upson and Anna Kuchment
Mitov has a light touch, writing like the hip, pop-culture-loving, corduroy-jacket-wearing chemistry teacher that you always wanted but never had.
Champagne bubbles, mayonnaise, rubber, blood and sand are part of the eclectic mix of materials explored in Sensitive Matter...Mitov applies his vivid imagination to explaining how soft materials respond to disturbances...It is a quirky and fun introduction to this practical, complex field.
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Read an Excerpt
From Chapter One: Peacemaking among enemies…easy when a mediator is involved
In 1756, the Duke of Richelieu’s chef brought back from Port Mahon (a town in the Balearic islands that the duke had conquered, in the military sense of the word) a recipe for a sauce based on olive oil and egg yolk. He called his discovery mahonnaise; later, it became mayonnaise. Of course, a story this specific about a preparation this famous is asking to be contested. And indeed, it is said, though less convincingly, that the word is derived from magnonaise (from magner or manier – to handle) or from moyeunaise (in the Middle Ages, the yolk of an egg was known as moyeu). It also (and still) appears that the inhabitants of la Mayenne and Bayonne make some claim to parentage based on phonetic proximity. At any rate, everybody would agree that oil does not mix with water; by this reasoning, it should not mix with egg yolk, either, which is 50 percent water. But why? Although, electrically speaking, a molecule of water is neutral, its atoms do carry charges: the single oxygen (O) has two negative charges, and each of the molecule’s two hydrogen (H) atoms has a positive charge. Two water molecules unite when a hydrogen atom on one is attracted to the oxygen atom on the other, forming a hydrogen bond. Molecules that contain OH groups generally form hydrogen bonds with water molecules. Oil molecules, on the other hand, are triglycerides composed of carbon and hydrogen. Their structure resembles a comb with three teeth and has no space for OH groups. Which brings us back to the question of how to bring oil and water together.
Can it be done? Temporarily, yes, because egg yolk contains not only water but also lecithin molecules, which act as mediators. Each consists of two parts: one water-loving (hydrophilic) and the other – two-tailed – that is water-hating (hydrophobic). We call these dual-affinity molecules amphiphiles from the Greek philos (friend) and amphi (both), which expresses the idea of a double possibility (an amphitheater has a left and a right side, an amphora has two handles). Amphiphilia will feature throughout our journey, whether the amphiphilic molecules be natural or synthetic, and their functions biological or industrial.
In creating a stable mayonnaise with an oil concentration of more than 60 percent, lecithin molecules play a double role. They coat the drops of oil by linking their water-hating tails to them; the resulting “spheres” are called micelles, from the Latin mica, for “morsel” (their thin-leaved structure enables mica fragments to be peeled apart). They also ensure the dispersion of the oil drops by exposing their hydrophilic heads to the water. The egg yolk proteins fulfill the same functions.
Micelles swell as oil is added, and the mix must be beaten all the while to break up the mass of oil into droplets. If too much oil is added, the drops coalesce into unequally sized larger drops. The mayonnaise then fails because there are no longer enough amphiphiles to protect all the interfaces between the oil and the water. If there is too much yolk, the sauce will taste overwhelmingly of egg. The consistency will also be too firm owing to the closeness of the oil drops. Not enough water can ruin a mayonnaise too, although adding a few drops of water, vinegar, or lemon juice while beating may resurrect it. Naturally, these measures also serve to soften the sauce, after which more oil can be added until it becomes too firm again, whereupon additional drops of water can be added, and so forth. This is a practical way of gradually optimizing the quantity of amphiphilic molecules. If the concentration in the aqueous phase (state) is too high, the result will be an emulsion of water in oil that risks catastrophic phase separation of the constituents. Mustard also contributes amphiphilic molecules.
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