A sputter coater may be purchased that deposits single layers of gold, gold-palladium, tungsten, chromium, platinum, titanium, or other metals in a very controlled thickness pattern. It is possible, and desirable, to coat only a few nm’s of metal onto the sample surface.
Spin coating
Many polymer films are depositing via a spin coater which spins a substrate (often ITO glass) and drops of polymer liquid are dispersed an even thickness on top of the substrate.
Staining
Another option for polymer sample preparation is staining the sample. Stains act in different ways, but typical stains for polymers are osmium tetroxide (OsO
4 ), ruthenium tetroxide (RuO
4 ) phosphotungstic acid (H
3 PW
12 O
40 ), hydrazine (N
2 H
4 ), and silver sulfide (Ag
2 S).
Examples
Comb-block copolymer (microstructure of cast film)
To view interior structure, the film was cut with a microtome or razor blade after the film was frozen in liquid N
2 and fractured.
Stained with RuO
4 vapor (after cutting).
Structure measurements were averaged over a minimum of 25 measurements.
SEM micrograph of comb block copolymer showing spherical morphology and long range order. Adapted from M. B. Runge and N. B. Bowden,
J. Am. Chem. Soc. , 2007,
129 , 10551. Copyright: American Chemical Society (2007).
Pressed polymer samples into disks and annealed for 16 h at 170 °C.
To determine ordered morphologies, the disk was fractured (see
[link] ).
Used SEM to verify lamellar spacing from USAXS.
SEM image of a fractured piece of polymer SL-1. Adapted from J. Rzayev,
Macromolecules , 2009,
42 , 2135. Copyright: American Chemical Society (2009).
Swnts in ultrahigh molecular weight polyethylene
Dispersed SWNTs in interactive polymer.
Samples were sputter-coated in gold to enhance contrast.
The films were solution-crystallized and the cross-section was imaged.
Environmental SEM (ESEM) was used to show morphologies of composite materials.
WD = 7 mm.
Study was conducted to image sample before and after drawing of film.
Images confirmed the uniform distribution of SWNT in PE (
[link] ).
M
W = 10,000 Dalton.
Study performed to compare transparency before and after UV irradiation.
SEM images of crystallized SWNT-UHMWPE films before (left) and after (right) drawing at 120 °C. Adapted from Q. Zhang, D. R. Lippits, and S. Rastogi,
Macromolecules , 2006,
39 , 658. Copyright: American Chemical Society (2006).
Nanostructures in conjugated polymers (nanoporous films)
Polymer and NP were processed into thin films and heated to crosslink.
SEM was used to characterize morphology and crystalline structure (
[link] ).
SEM was used to determine porosity and pore size.
Magnified orders of 200 nm - 1 μm.
WD = 8 mm.
M
W = 23,000 Daltons
Sample prep: spin coating a solution of poly-(thiophene ester) with copper NPs suspended on to ITO coated glass slides. Ziess, Supra 35
SEM images of thermocleaved film loaded with nanoparticles with scale bar 1 μm. Adapted from J. W. Andreasen, M. Jorgensen, and F. C. Krebs,
Macromolecules , 2007,
40 , 7758. Copyright: American Chemical Society (2007).
Used cryogenic SEM (cryo-SEM) to visualize the microstructure of particles (
[link] ).
Particles were immobilized by fast-freezing in liquid N
2 at –196 °C.
Sample is fractured (-196 °C) to expose cross section.
3 nm sputter coated with platinum.
Shapes of the nanoparticles after fracture were evaluated as a function of crosslink density.
Cryo-SEM images of plastically drawn polystyrene and latex particles. Adapted from H. Ge, C. L. Zhao, S. Porzio, L. Zhuo, H. T. Davis, and L. E. Scriven,
Macromolecules , 2006,
39 , 5531. Copyright: American Chemical Society (2006).
Bibliography
H. Ge, C. L. Zhao, S. Porzio, L. Zhuo, H. T. Davis, and L. E. Scriven,
Macromolecules , 2006,
39 , 5531.
J. Rzayev,
Macromolecules , 2009,
42 , 2135.
J. W. Andreasen, M. Jorgensen, and F. C. Krebs,
Macromolecules , 2007,
40 , 7758.
M. B. Runge and N. B. Bowden,
J. Am. Chem. Soc. , 2007,
129 , 10551.
P. J. Goodhew, J. Humphreys, and R. Beanland,
Electron Microscopy and Analysis , Taylor&Francis Inc., New York (2001).
Q. Zhang, D. R. Lippits, and S. Rastogi,
Macromolecules , 2006,
39 , 658.
Questions & Answers
Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you.
Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Source:
OpenStax, Physical methods in chemistry and nano science. OpenStax CNX. May 05, 2015 Download for free at http://legacy.cnx.org/content/col10699/1.21
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