Fibers and Coatings

a) I’ll start by the arguments why our group decided to examine and make improvements in this direction, to be exact, in nanocristalline diamond. Second I’m going to touch upon the main problem we tried to overcome in the course of our research and explain what way we managed to solve it. My third point is concerned with methods and techniques, with special attention to electrospinning, we applied to tailor specified properties for new materials. Then, I’d like to talk about characteristics and properties of the films and fibers obtained and finally I want to show how and where these unique nanomaterials can be used.

b) Dear collegues, it’s a well-known fact that nanocrystalline diamond is quickly becoming one of the most widely studied nanomaterials, however achieving a large fraction of diamond nanoparticles in a polymer coating and fibers has been an unresolved problem.

c) Nanodiamond (ND) powder, also known as ultradispersed diamond (UDD), exhibits unique properties of diamond on the nanoscale and is becoming one of the more widely studied nanomaterials. Superior hardness and thermal conductivity of the diamond core is combined in nanodiamond powders with large accessible surface area covered by readily tailorable surface functional groups....

d) Dear colleagues! It is good to see you all here today. Let me first introduce myself. My name is Vadim Molchanov I’m a senior associate of MSc& E laboratory. At this conference I represent the international research group from Drexel Nanotechnology Institute. We carry out our investigations in the Department of Materials Science and Engineering.

e) The title of the report is “Nanodiamond-Polymer Composite Fibers and Coatings”.

f) Next half an hour or so I’m going to report about the latest achievements and developments we’ve performed in the nanocomposite field. Ladies and gentlemen, if you’ll have any questions, please, feel free to ask them any time.

g) ND is produced by a detonation synthesis in large volumes and is a relatively inexpensive carbon nanomaterial for a broad range of potential applications, including composites.

h) So, as it’s seen from the title, this presentation is devoted to the composite fibers and coatings made of hybrid nanomaterial, containing nanodiamond powder (ND).

i) One major obstacle for ND composites is the ability to deliver nanodiamond in the form of well-dispersed particles into a polymer matrix. Traditional polymer processing techniques such as casting and extrusion have yielded poor dispersion due to agglomeration/reagglomeration of the nanodiamonds within the polymer matrix leading to a compromise of the properties. Besides, the addition of more than several percent of nanodiamond to the whole volume of a polymer component would substantially increase the cost and weight. Therefore, diamond should preferably be used in those places where it is needed, for example as a surface coating.

j) In particular there are 3 main items which I wish to put you this afternoon.

k) While there have been more than a hundred of articles published on electrospun polymer-nanotube fibers in the past 5 years, there are no reports on electrospun ND-polymer fibers therefore one of the objectives of our work was to demonstrate feasibility of manufacturing composite polymer-nano-diamond fibers by electrospinning.

l) Fibers and films of polyacrylonitrile (PAN) and ND have been manufactured and characterized. To show the applicability of this method to other polymer systems, we also introduced diamond into polyamide 11 (PA-11). Next show-room you can see the test-samples which are ready for serial production.

m) I’d like to pay your attention that electrospinning provides many benefits stemming from the small and tunable fiber diameter. Polymer composites produced via the electrospinning method allow for a polymer nanofiber to act as a host for nanoparticles.Polymer nanofibers can be used as a coating or appliques, thus delivering nanodispersed particles while effectively preventing their agglomeration. The confinement of the fiber diameter, polymer surface tension, and strong electrostatic force pulling the fiber in the electrospinning process may help in deagglomeration of nanopartides, similarly as it has led to a debundling of single-walled carbon nanotubes and their alignment along the fiber axis. So far, various nanomaterials have been incorporated into electrospun fibers. Among them are ceramic nanonanowires, quantum dots, nanotubes, and others.

n) By harnessing electrospinning as a procedure to produce and apply thin films to various substrates, ND-polymer composites could be transformed into thin scratch-resistant coatings that would effectively protect from UV rays on windows, or prevent degradation of UV sensitive materials. Moreover, ND powders, being biocompatible and having a tailorable, and easily accessible surface, certainly have a great potential to be used as a filler of a polymer matrix in many applications.

o) And, what is more, we’ll further be able to show that these fibers can be used for producing thin and transparent diamond-containing coatings with very high diamond contents.

Read and translate the short fragments which were not included in the presentation. Look through the text of presentation again and unite each fragment with the appropriate part of presentation.

1. In addition, as soon as the fiber solidifies upon evaporation of the solvent during electrospinning, reagglomeration of nanopartides is effectively suppressed; thus, a resulting nanocomposite incorporates uniformly dispersed, size-confined nanopartides.

2. Diamond- containing electrospun fibers could be used for biomedical applications such as wound dressings, cell growth scaffolds, sensing, and drug delivery systems, as well as in smart and UV-protecting clothing.

3. Thus, as you’ve seen, polymer nano- and microfibers containing high loadings of 5 nm diamond particles (up to 80 wt % in polyacrylonitrile and 40% in polyamide-11) have been demonstrated using electrospun nanofibers as a delivery vehicle.

4. The electrospun nanofibers with a high load of nanodiamond in the polymers were fused into thin transparent films, which had high mechanical properties; an improvement of 4 times for the Young's modulus and 2 times for the hardness was observed already at 20% nanodiamond in polyamide-11.

5. As a powder, ND could be introduced into fibers, coatings, or other shapes to harness its useful properties.

9. Make your own presentation. Then look through it again and answer the questions concerning: