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Polymer sample preparation techniques

Sputter coating

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)

  • Cast polymer film (see [link] ).
  • 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).

Polystyrene-polylactide bottlebrush copolymers (lamellar spacing)

  • 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).

Cryo-sem colloid polystyrene latex particles (fracture patterns)

  • 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

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
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Damian Reply
absolutely yes
Daniel
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Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
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On having this app for quite a bit time, Haven't realised there's a chat room in it.
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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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