How Do Micelles Work

Click on the left mouse button and rotate the soap structure.

Soaps are mixtures of sodium or potassium salts of fatty acids which can be derived from oils or fats by reacting them with an alkali (such as sodium or potassium hydroxide) at 80°–100 В°C in a process known as saponification.В

fat + NaOH —> glycerol + sodium salt of fatty acidВ

Try this!!В

Click the right mouse button with the cursor over the image—>

Style —>Labels —> Element Symbols

Click on the left mouse button and rotate the soap structure.

Notice that one end of the molecules is made up of a hydrocarbon chain — the other end is a very polar structure containing oxygen and sodium.

Soap molecules have both properties of non-polar and polar at opposite ends of the molecule.

How does Soap Work?

Nearly all compounds fall into one of two categories: hydrophilic (‘water-loving’) and hydrophobic (‘water-hating’).В WaterВ and anything that will mix with water are hydrophilic. Oil and anything that will mix with oil are hydrophobic. When water and oil are mixed they separate. Hydrophilic and hydrophobic compounds just don’t mix.В

The cleansing action of soap is determined by its polar and non-polar structures in conjunction with an application of solubility principles.В The long hydrocarbon chain is non-polar and hydrophobic (repelled by water).В The «salt» end of the soap molecule is ionic and hydrophilic (water soluble).

Soap is a natural surfactant. A surfactant is any substance that tends to reduce the surface tension of a liquid in which it is dissolved.

The science of how things work has always fascinated me. So, How Does Soap Work?

Soap, water, and oil are all made up of molecules. Some molecules are hydrophilic, (hydro=water and philic=loving) these molecules are attracted to water. Some molecules are hydrophobic, (hydro=water and phobic=fearing), they are repelled by water.

Molecules that readily mix with water are hydrophilic.

Molecules that readily mix with oil are hydrophobic.

Since we all know that water and oil do not mix, then we also know that hydrophilic and hydrophobic compounds do not mix.

Two other words we need to know are polar and nonpolar. Nonpolar compounds, like oil and grease, cannot dissolve in water. Polar compounds can dissolve in water.

Most of what we call dirt is grease or oil which will not come off with just water. This is because oil and grease are non-polar, which means they will not dissolve in the water.

Soap can mix with both water and with oil. Why? The soap molecule has two different ends, one that is hydrophilic (polar head) that binds with water and the other that is hydrophobic (non-polar hydrocarbon tail) that binds with grease and oil.

When greasy dirt or oil is mixed with soapy water, the soap molecules arrange themselves into tiny clusters called micelles.

The water-loving (hydrophilic) part of the soap molecules sticks to the water and points outwards, forming the outer surface of the micelle.

The oil-loving (hydrophobic) parts stick to the oil and trap oil in the center where it can’t come into contact with the water.

With the oil tucked safely in the center, the micelle is soluble in water. As the soapy water is rinsed away the greasy dirt goes along with it. Micelle Picture from Wikipedia

So basically, the soap is attracted to the fat/oil/grease because of its fat-loving side but then tears up the grease by pulling it into the water using its water-loving side. Sounds kind of like a football play—surround the oil particles and move them away from one another.

Ever wonder why it is easier to clean dirty, greasy hands (and other things) in hot or warm water rather than cold water? It is because the fats and oils soften or melt in hot water, which allows them to attach more readily to the hydrophobic end of the soap molecule. In turn, that makes it easier to rinse away.

Soap is a natural surfactant. A surfactant is any substance that tends to reduce the surface tension of a liquid in which it is dissolved.

Almost all cleansing products are based on surfactants. Surfactants not only reduce the surface tension of the water but the way they are constructed (with one hydrophilic end and one hydrophobic end) makes them compatible with both water and oils. This property is what makes them good for cleansing. When surfactants lower the surface tension of water, they basically make the water molecules more slippery, so they are less likely to stick to themselves and more likely to interact with oil and grease.

Natural soap needs no synthetic additives to create lather or to clean because natural soap is a natural surfactant. So it not only makes great bubbles and lather, but it also helps clean oily dirt from your skin—naturally!

You can think of soap as the middle-man that helps bring oil and water together so that the dirt and grease on your skin can be easily rinsed away.

A new buzzword in the hair and beauty industry is “micellar,” and products with this adjective may tout “dirt-magnet” or other such cleansing properties.

Thursday

A new buzzword in the hair and beauty industry is “micellar,” and products with this adjective may tout “dirt-magnet” or other such cleansing properties.

A new buzzword in the hair and beauty industry is “micellar,” and products with this adjective may tout “dirt-magnet” or other such cleansing properties.

See also:  How Many Mice In A Nest

To understand this technology, one must first know a chemistry tidbit: A micelle is a mass of molecules that has the ability to dissolve and move non-polar substances through an aqueous medium. Or, as Women’s Health magazine explained in December, in a way readers could comprehend, a micelle is a molecule that has opposite ends — one that is attracted to water and one that is attracted to oil. In essence, these micelles both grab what they need out of hair and off the face, and are able to rinse away easily.

Micelle-infused products are touted by some as solutions to eliminating chlorine, salt, sunscreen and sand from hair after a day of fun in the sun. Often products list the ingredient as “micellar water.”

Skin care products with micelles work to mildly draw impurities from the skin without drying it out. What micellar water will not do on its own is remove heavy eye or face makeup.

Since micelle-infused products are relatively new to the general marketplace, Women’s Health advises experimentation with a few different products. Individuals can judge which ones work on their hair and skin types. There are plenty to choose from; beauty salons have them, as do pharmacies and popular mass merchandisers.

Expect to pay as much for particular brands of hair and skin care products with micelles as without.

Handwashing with soap is easy, inexpensive, and it saves lives. Seems like common sense, but how does handwashing with soap actually work? Why can’t you just use water? What even is soap?

Handwashing with soap is easy, inexpensive, and it saves lives. Seems like common sense, but how does handwashing with soap actually work? Why can’t you just use water? What even is soap?

To answer these questions, we’ll need to go back to school.

An ancient remedy

First, a history lesson. Humans have been using soap for a long, long time. The earliest recorded evidence of the production of soap dates back to around 2800 BC in ancient Babylon. Long before humans understood modern chemistry or biology, they noticed that certain materials, when mixed with water, did a much better job of cleaning than water alone.

At the most basic level, soap is a special type of salt derived from vegetable or animal fats or oils—for example, tallow (rendered beef fat), coconut oil, and olive oil are all popular soap bases. The oil or fat is combined with an alkaline metal solution, which breaks it down into the salt. Depending on additives, byproducts, and materials used, the final soap product can be solid, liquid, thick, thin, oily, or greasy. All types of soap do the same thing: remove dirt and the disease-causing germs it contains.

Removing dirt & germs, one micelle at a time

So, how does soap clean the dirt, grease, and oils off of your hands? To answer that, we’ll need a visit to chemistry class.

Soap molecules dislodge dirt, oil, and grease particles — and the disease-causing germs they carry — from your hands, one micelle at a time. [Source]

When you wash your hands with soap, it dislodges the dirt, grease, oils, and disease-ridden fecal matter particles on your hands by creating these micelles. Surrounded by the soap, the oil molecules become suspended and distributed in the water rather than stubbornly clinging to your skin. This allows the dirt and germs on your skin—or on clothing, surfaces, or towels—to be rinsed away with the water. Ta-da!

Today’s challenge

So now we know what’s happening on a molecular level, but what about the community level? Why does handwashing with soap matter so much for global health? And if soap has been around for so long, why are we still talking about it today?

For these questions, we need lessons from public health and the social sciences. The benefits of handwashing with soap are numerous. It significantly reduces the risk of diarrhea, typhoid, respiratory illnesses, and lots of other waterborne and infectious diseases. It is estimated that universal handwashing with soap could prevent 30% of all diarrhea cases. And because handwashing reduces illnesses and their long-term complications, handwashing also helps improve child growth, development, and school attendance around the world.

The problem is that, despite the low cost and ease of using soap, handwashing with soap is rarely practiced as often as it needs to be. Handwashing with soap requires water and soap to be available when and where people are relieving themselves, and 2.3 billion people worldwide still lack access to basic sanitation. Education and behavior change interventions are needed, too.

We can change this. Universal handwashing with soap is an essential part of the toolkit required to defeat diarrheal disease and help every child thrive. To reach this goal, governments, the private sector, civil society, and other stakeholders need to work together to promote handwashing with soap alongside clean water and sanitation.

We all need to give each other a hand – a clean hand, that is! Thankfully, soap is here to help make that happen.

If you are the author of this article you do not need to formally request permission to reproduce figures, diagrams etc. contained in this article in third party publications or in a thesis or dissertation provided that the correct acknowledgement is given with the reproduced material.

Article information

Polymeric micelles as drug delivery vehicles

If you are not the author of this article and you wish to reproduce material from it in a third party non-RSC publication you must formally request permission using Copyright Clearance Center. Go to our Instructions for using Copyright Clearance Center page for details.

Authors contributing to RSC publications (journal articles, books or book chapters) do not need to formally request permission to reproduce material contained in this article provided that the correct acknowledgement is given with the reproduced material.

See also:  How Are Mice Getting In My Basement

Reproduced material should be attributed as follows:

  • For reproduction of material from NJC:
    Reproduced from Ref. XX with permission from the Centre National de la Recherche Scientifique (CNRS) and The Royal Society of Chemistry.
  • For reproduction of material from PCCP:
    Reproduced from Ref. XX with permission from the PCCP Owner Societies.
  • For reproduction of material from PPS:
    Reproduced from Ref. XX with permission from the European Society for Photobiology, the European Photochemistry Association, and The Royal Society of Chemistry.
  • For reproduction of material from all other RSC journals and books:
    Reproduced from Ref. XX with permission from The Royal Society of Chemistry.

If the material has been adapted instead of reproduced from the original RSC publication «Reproduced from» can be substituted with «Adapted from».

In all cases the Ref. XX is the XXth reference in the list of references.

If you are the author of this article you do not need to formally request permission to reproduce figures, diagrams etc. contained in this article in third party publications or in a thesis or dissertation provided that the correct acknowledgement is given with the reproduced material.

Reproduced material should be attributed as follows:

  • For reproduction of material from NJC:
    [Original citation] — Reproduced by permission of The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC
  • For reproduction of material from PCCP:
    [Original citation] — Reproduced by permission of the PCCP Owner Societies
  • For reproduction of material from PPS:
    [Original citation] — Reproduced by permission of The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC
  • For reproduction of material from all other RSC journals:
    [Original citation] — Reproduced by permission of The Royal Society of Chemistry

If you are the author of this article you still need to obtain permission to reproduce the whole article in a third party publication with the exception of reproduction of the whole article in a thesis or dissertation.

Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

«Micellar stratification in soap films: a light scattering study»
O. Krichevsky and J. Stavans, Phys. Rev. Lett. 74, 2752 (1995).

Architecture of soap films and the forces that stabilize them

Soap films are nothing more than thin liquid layers whose water-air interfaces have been stabilized by a surfactant. The picture below illustrates an ideal soap film:

In reality there is always excess surfactant remaining in solution. Surfactants have a dual character built-in within the same molecule: part of it -the head- is hydrophilic, whereas the other part — the tail- is hydrophobic. The surfactant molecules remaining within the water core need to shield their tails from water as much as possible. To do so, they self-assemble into quasi-spherical structures called micelles:

Thickness h vs time t of a film drawn from a solution with c=12 wt %

«Micellar stratification in soap films: a light scattering study»
O. Krichevsky and J. Stavans, Phys. Rev. Lett. 74, 2752 (1995).

«Confined fluid between two walls: the case of micelles inside a soap film»
O. Krichevsky and J. Stavans, Phys. Rev. E. 55, 7260 (1997).

The CMC is also important in determining which method should be used for detergent removal as detergents may interfere with certain applications. Detergents with high CMCs are easily removed by dialysis ( Tube-O-DIALYZER™). D etergents with low CMCs are typically removed by adsorption to hydrophobic beads ( DetergentOUT™ Tween ®) or be removed by column chromatography (DetergentOUT™ GBS10).

The CMC is also important in determining which method should be used for detergent removal as detergents may interfere with certain applications. Detergents with high CMCs are easily removed by dialysis ( Tube-O-DIALYZER™). D etergents with low CMCs are typically removed by adsorption to hydrophobic beads ( DetergentOUT™ Tween ®) or be removed by column chromatography (DetergentOUT™ GBS10).

For more information on detergents, membrane protein isolation and micelles, check out our other Protein Man Blogs:

So, hydrolysis of a fat under basic conditions, such as with hydroxide, generates glycerol and three molecules of the fatty acid carboxylate. It is these carboxlyates that are the soap molecules, and historically this is exactly how soap was made, i.e. by «cooking» fats with sodium hydroxide in the form of lye.

O-Chem in Real Life: Soaps and Detergents

The definition of a carboxylic acid derivative is a compound that hydrolyzes (usually with an acid or base catalyst) to a carboxylic acid. An ester hydrolyzes to a carboxylic acid and an alcohol. If this hydrolysis is performed in the presence of base, then the anionic form of the carboxylic acid is formed, the carboxylate anion.

So, hydrolysis of a fat under basic conditions, such as with hydroxide, generates glycerol and three molecules of the fatty acid carboxylate. It is these carboxlyates that are the soap molecules, and historically this is exactly how soap was made, i.e. by «cooking» fats with sodium hydroxide in the form of lye.

Soap molecules have problems in hard water. Hard water contains minerals in the form of salts, for example that from the SALT RIVER!! Magnesium and calcium salts are particularly problematic. Although sodium carboxylates are water soluble, calcium and magnesium carboxylates tend to be much less water soluble. Adding soap to water hard water forms soap «scum», i.e. precipitates of calcium and magnesium carboxylates.

Calcium and magnesium salts of sulfonates are water soluble, thus the soap scum problem is solved! There is a problem, however. Since soaps are natural products they are fairly biodegradable, whereas the non-natural detergents are often not biodegradable, leading to foamy looking polluted water. Chemists are currently working on more efficient detergents that do biodegrade.

See also:  How Mice Get In Basement

I once did quite a lot of work on photochemical reactions in soaps and related structures. Because many organic molecules locate themselves inside hydrophobic interiors of micelles, they can act as tiny reactors or cages for organic molecules. These tiny reactors could be used to alter the course of and control many chemical reactions in interesting ways.

For simplicity, let’s consider only the air-water interface. The cohesive forces between the water molecules are very strong making the surface tension of water high. As surfactants absorb they break these interactions. The intermolecular forces between surfactant and water molecule are much lower than between two water molecules and thus surface tension will decrease. When the surfactant concentration is high, they form micelles. The point at which micelles are formed is called critical micelle concentration.

Surfactants absorb at interfaces

Because of their amphiphilic nature, surfactants absorb at the air-water or oil-water interface. At the interface, surfactants align themselves so that the hydrophobic part is in air (or oil) and hydrophilic part in water.

For simplicity, let’s consider only the air-water interface. The cohesive forces between the water molecules are very strong making the surface tension of water high. As surfactants absorb they break these interactions. The intermolecular forces between surfactant and water molecule are much lower than between two water molecules and thus surface tension will decrease. When the surfactant concentration is high, they form micelles. The point at which micelles are formed is called critical micelle concentration.

The main purpose of the surfactants is to decrease the surface and interfacial tension and stabilize the interface. Without surfactants washing laundry would be difficult and many of the food products like mayonnaise and ice cream would not exist. Thus optimization of surfactants for different applications is highly important and surface and interfacial tension measurements have the key role in it.

If you would like to read more how surfactants are utilized in industry, please download the overview below.

Pre-Class Questions: Lipid Structure: B. Lipids in Water — Question

  • Contributed by Henry Jakubowski
  • Professor (Chemistry) at College of St. Benedict/St. John’s University

A post-doc once told me that to understand biochemistry and immunology, he had to pretend that he was a molecule. We want to know how lipid molecules, specifically single and double chain amphiphiles, interact with each other and solvent when they are added to water. Before you read the answer, look at the image below and ask yourself the question: What would I do if I were a single chain amphiphile ready to jump into water?

A single chain amphiphile jumps into water!

When added to water, single chain amphiphiles form both monolayers on the surface of the water and micelles, while some monomer remain in solution. Double chain amphiphiles form bilayers instead of micelles. (Note: single and double chain amphiphiles can form other multimolecular aggregate structures as well, but these are the most common and are the only ones we will consider. )

Figure: Structures of single and double chain amphipiles in water — Micelles and Bilayers

Jmol Updated Micelle Jmol14 (Java) | JSMol (HTML5)

Jmol: Updated Nonhydrated Bilayer Jmol14 (Java) | JSMol (HTML5)

Common single chain amphiphiles that form micelles are detergents (like sodium dodecyl sulfate — SDS) as well as fatty acids, which themselves are detergents. NaOH feels slippery on your skin since the base hydrolyses the fatty acids esterified to skin lipids. The free fatty acids then aggregate spontaneously to form micelles which act like detergents.

Pre-Class Questions: Lipid Structure: B. Lipids in Water — Question

Liposomes produced in the lab can be unilamellar, consisting of a single bilayer surrounding the internal aqueous compartment, or multilamellar, consisting of multiple bilayers surrounding the enclosed aqueous solution. You can image the multilamellar vesicles resembles an onion with its multiple layers. Cartoons of unilamellar and multilamellar liposomes are shown below, where each concentric circle represents a bilayer.

Given the large degree of unsaturation at C2, what do you expect the transition temperature of a liposome composed only of egg yolk PC to be? (Vesicles made using more saturated PC from mammalian sources have (T_m) of around 40ºC.) This high degree of unsaturation makes egg yolk PC very susceptible to oxidation, which could alter the properties of the liposome dramatically. Synthetic PC made with saturated fatty acids could alleviate that problem.

Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in a chemical reaction called saponification. Each soap molecule has a long hydrocarbon chain, sometimes called its ‘tail’, with a carboxylate ‘head’. In water, the sodium or potassium ions float free, leaving a negatively-charged head.

The Disadvantage of Soap

Although soaps are excellent cleansers, they do have disadvantages. As salts of weak acids, they are converted by mineral acids into free fatty acids:

These fatty acids are less soluble than the sodium or potassium salts and form a precipitate or soap scum. Because of this, soaps are ineffective in acidic water. Also, soaps form insoluble salts in hard water, such as water containing magnesium, calcium, or iron.

The insoluble salts form bathtub rings, leave films that reduce hair luster, and gray/roughen textiles after repeated washings. Synthetic detergents, however, may be soluble in both acidic and alkaline solutions and don’t form insoluble precipitates in hard water. But that is a different story.

Source
http://www.worldofmolecules.com/3D/how-does-soap-work.html
http://www.chagrinvalleysoapandsalve.com/blog/posts/how-does-soap-work/
http://www.providencejournal.com/zz/timeandmoney/20180621/what-are-micelles-and-what-are-they-doing-in-my-shampoo
http://www.defeatdd.org/blog/how-does-soap-actually-work
http://pubs.rsc.org/en/content/articlelanding/2014/ra/c3ra47370h#!divAbstract
http://www.weizmann.ac.il/complex/stavans/liquids-confined-gerometries-micelles-soap-films
http://info.gbiosciences.com/blog/importance-of-detergent-micelle-levels-in-membrane-protein-purification
http://www.asu.edu/courses/chm233/notes/derivatives/derivativesRL2/soap.html
http://www.biolinscientific.com/blog/what-are-surfactants-and-how-do-they-work
http://bio.libretexts.org/Bookshelves/Biochemistry/Book%3A_Biochemistry_Online_(Jakubowski)/01%3A_LIPID_STRUCTURE/1.2%3A_Lipids_in_Water/1.2A%3A_Micelles_and_Bilayers
http://www.thoughtco.com/how-dos-soap-clean-606146
Share:
No comments

Добавить комментарий

Your e-mail will not be published. All fields are required.

×
Recommend
Adblock
detector