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20-434: (Redirected from Langmuir-Blodgett ) Langmuir-Blodgett may refer to: Langmuir–Blodgett film Langmuir–Blodgett trough Irving Langmuir and Katharine Burr Blodgett Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Langmuir–Blodgett . If an internal link led you here, you may wish to change

40-506: A hydrophilic head and a hydrophobic tail (example: fatty acids ) or nowadays commonly of nanoparticles . Langmuir–Blodgett films are named after Irving Langmuir and Katharine B. Blodgett , who invented this technique while working in Research and Development for General Electric Co. Advances to the discovery of LB and LM films began with Benjamin Franklin in 1773 when he dropped about

60-425: A gas in a container. The density of surfactant molecules as well as the surface pressure increases upon reducing the surface area A ('compression' of the 'gas'). Further compression of the surfactant molecules on the surface shows behavior similar to phase transitions . The ‘gas’ gets compressed into ‘liquid’ and ultimately into a perfectly closed packed array of the surfactant molecules on the surface corresponding to

80-409: A simple anti-reflective coating . Langmuir films are formed when amphiphilic (surfactants) molecules or nanoparticles are spread on the water at an air–water interface. Surfactants (or surface-acting agents) are molecules with hydrophobic 'tails' and hydrophilic 'heads'. When surfactant concentration is less than the minimum surface concentration of collapse and it is completely insoluble in water,

100-532: A solid substrate to create highly organized thin film coatings. Langmuir–Blodgett troughs Besides LB film from surfactants depicted in Figure 1, similar monolayers can also be made from inorganic nanoparticles. Adding a monolayer to the surface reduces the surface tension , and the surface pressure, Π {\displaystyle \Pi } is given by the following equation: where γ 0 {\displaystyle \gamma _{0}}

120-611: A solid surface is inserted into an aqueous solution containing organic moieties, the organic molecules will deposit a monolayer homogeneously over the surface. This is the Langmuir–Blodgett film deposition process. Through this work in surface chemistry and with the help of Blodgett, Langmuir was awarded the Nobel Prize in 1932. In addition, Blodgett used Langmuir–Blodgett film to create 99% transparent anti-reflective glass by coating glass with fluorinated organic compounds, forming

140-400: A teaspoon of oil onto a pond. Franklin noticed that the waves were calmed almost instantly and that the calming of the waves spread for about half an acre . What Franklin did not realize was that the oil had formed a monolayer on top of the pond surface. Over a century later, Lord Rayleigh quantified what Benjamin Franklin had seen. Knowing that the oil, oleic acid , had spread evenly over

160-537: A ‘solid’ state. The liquid state is usually separated in the liquid-expanded and liquid-condensed states. All the Langmuir film states are classified according to the compressionality factor of the films, defined as -A(d ( Π {\displaystyle \Pi } )/dA), usually related to the in-plane elasticity of the monolayer. The condensed Langmuir films (in surface pressures usually higher than 15 mN/m – typically 30 mN/m) can be subsequently transferred onto

180-417: Is equal to the surface tension of the water and γ {\displaystyle \gamma } is the surface tension due to the monolayer. But the concentration-dependence of surface tension (similar to Langmuir isotherm ) is as follows: Thus, or The last equation indicates a relationship similar to ideal gas law . However, the concentration-dependence of surface tension is valid only when

200-450: Is the difference in forces. The Wilhelmy plate measurements give pressure – area isotherms that show phase transition-like behaviour of the LM films, as mentioned before (see figure below). In the gaseous phase, there is minimal pressure increase for a decrease in area. This continues until the first transition occurs and there is a proportional increase in pressure with decreasing area. Moving into

220-895: The affected area since the organic molecules were arranged vertically. Langmuir’s breakthrough did not occur until he hired Katherine Blodgett as his assistant. Blodgett initially went to seek for a job at General Electric ( GE ) with Langmuir during her Christmas break of her senior year at Bryn Mawr College , where she received a BA in Physics . Langmuir advised to Blodgett that she should continue her education before working for him. She thereafter attended University of Chicago for her MA in Chemistry . Upon her completion of her Master's, Langmuir hired her as his assistant. However, breakthroughs in surface chemistry happened after she received her PhD degree in 1926 from Cambridge University . While working for GE, Langmuir and Blodgett discovered that when

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240-518: The link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Langmuir–Blodgett&oldid=932957853 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Langmuir%E2%80%93Blodgett film The monolayers are assembled vertically and are usually composed either of amphiphilic molecules (see chemical polarity ) with

260-743: The monolayer collapse may remain approximately constant (in a process near the equilibrium) or may decay abruptly (out of equilibrium - when the surface pressure was over-increased because lateral compression was too fast for monomolecular rearrangements). Many possible applications have been suggested over years for LM and LB films. Their characteristics are extremely thin films and high degree of structural order. These films have different optical, electrical and biological properties which are composed of some specific organic compounds. Organic compounds usually have more positive responses than inorganic materials for outside factors ( pressure , temperature or gas change). LM films can be used also as models for half

280-455: The plate leads to the following equation for the surface pressure: only when w p ≫ t p {\displaystyle w_{p}\gg t_{p}} . Here, ℓ p , w p {\displaystyle \ell _{p},w_{p}} and t p {\displaystyle t_{p}} are the dimensions of the plate, and Δ F {\displaystyle \Delta F}

300-413: The solid region is accompanied by another sharp transition to a more severe area dependent pressure. This trend continues up to a point where the molecules are relatively close packed and have very little room to move. Applying an increasing pressure at this point causes the monolayer to become unstable and destroy the monolayer forming polylayer structures towards the air phase. The surface pressure during

320-494: The solutions are dilute and concentrations are low. Hence, at very low concentrations of the surfactant, the molecules behave like ideal gas molecules. Experimentally, the surface pressure is usually measured using the Wilhelmy plate . A pressure sensor/electrobalance arrangement detects the pressure exerted by the monolayer. Also monitored is the area to the side of the barrier which the monolayer resides. A simple force balance on

340-533: The surface density compatible with the collapse of the monolayer (which leads to polylayers structures) the surfactant molecules execute a random motion on the water–air interface. This motion can be thought to be similar to the motion of ideal-gas molecules enclosed in a container. The corresponding thermodynamic variables for the surfactant system are, surface pressure ( Π {\displaystyle \Pi } ), surface area (A) and number of surfactant molecules (N). This system behaves similar to

360-481: The surfactant molecules arrange themselves as shown in Figure 1 below. This tendency can be explained by surface-energy considerations. Since the tails are hydrophobic, their exposure to air is favoured over that to water. Similarly, since the heads are hydrophilic, the head–water interaction is more favourable than head-air interaction. The overall effect is reduction in the surface energy (or equivalently, surface tension of water). For very small concentrations, far from

380-406: The water, Rayleigh calculated that the thickness of the film was 1.6  nm by knowing the volume of oil dropped and the area of coverage. With the help of her kitchen sink, Agnes Pockels showed that area of films can be controlled with barriers. She added that surface tension varies with contamination of water. She used different oils to deduce that surface pressure would not change until area

400-435: Was confined to about 0.2 nm . This work was originally written as a letter to Lord Rayleigh who then helped Agnes Pockels become published in the journal, Nature , in 1891. Agnes Pockels’ work set the stage for Irving Langmuir who continued to work and confirmed Pockels’ results. Using Pockels’ idea, he developed the Langmuir (or Langmuir–Blodgett ) trough. His observations indicated that chain length did not impact

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