The Electrospinning Process

While looking around on YouTube, I found a few interesting videos that highlight a few aspects of electrospinning:

The first video (below) shows an actual stream of nanofiber coming out of a charged syringe. At first, the stream is very well-defined, ; however, it soon becomes blurry due to rapid movement. This movement is an observable phenomenon in which the charged fiber forms a natural cone in an attempt to distance itself from the rest of its own identically charged length.

http://www.youtube.com/watch?v=87uRQ7KwbB0

As a side note, just as the nanofiber solution leaves the charged syringe, another natural phenomenon can be observed in the form of a Taylor Cone (labeled in the picture below). A Taylor Cone is fascinating because it refers the the tendency for a droplet of liquid/solution to deform from its normal spherical shape in the presence of excessive charge. This deformity causes the solution to be stretched into a fiber that measures in the nanometer scale, and thus creates nanofibers.

http://www.chromacademy.com/Electrospray-Ionization-ESI-for-LC-MS.asp?tpm=1_1

One other video caught my interest because it adequately describes the process through which we have decided to electrospin. As shown in the previous YouTube video, a typical elctrospinning setup includes one charged syringe, and thus, only one jet of nanofiber. This setup works, but is not efficient because it could take ninety minutes or more to create enough fiber to have a workable sample. However, as shown in the video below at time 1:50, various groups are in the process of designing a more efficient method of electrospinning. We have taken this type of design as our model, and hope to optimize it for the most efficient production of quality nanofibers. While the segment of the video from 1:50 - 2:12 deals with the basis behind our design, the rest of the video provides a general overview to the entire proces of nanofiber production.

http://www.youtube.com/watch?v=zhZ2u_tZFP4&feature=related

April 25th Events

Today Matt and I went to lab to create our first batch of polymer solution, which will eventually be tested in our K'Nex electrospinner. It was rather simple to create the solution, as we just collected the components, carefully massed them on a high precision scale, and mixed them together. The solution consisted of 4.5 grams of dimethylformamide and .5 grams of polyacrylontrile. Below is a picture of the finished solution:

This solution has undergone various testings at Drexel in the past, and once electrospun a nanofilm of this solution will calcinate into carbon nanofibers at approximately 800 degrees celsius. Later in the week, (once the components are completely in solution) Matt and I will use this solution in electrospinning (with an electrospinner from another lab) and practice our first calcination.

Meanwhile, Nikita and Travis have successfully completed their initial design for our K'Nex Electrospinner! While there will be optimizations to be made based on electrospinning tests, the base design is complete and the group is right on schedule with making a successful K'Nex electrospinner, and using it to electrospin a polymer solution that will be calcinated into carbon nanofibers. In lab later today our group will be conducting the first tests on this electrospinner, and noting improvements that need to be made. Later Nikita will add pictures and data from the first electrospinning trial.


-Nick Pescatore

Week 3 Review

During the past week, Nick and I were trained in the techniques of various performance analysis tests that are able to be run on calcinated nanofibers, which included both the cyclic voltammetry and cyclic charge-discharge tests. The ability to be able to perform these tests will allow us to analyze our product nanofibers and to hopefully compare their efficiencies to that of the other conductive material.

As for the electrospinner itself, Travis and Nikita believe that they are finished with the optimizations; however, unfortunately, we were not able to test their optimized design due to a lack of lab space, which will hopefully be resolved soon.

Nanofiber Application Research

For the second part of our project, Nick and I are researching the remainder of the process through which the spun nanofibers are modified into carbon nanofibers, which can be used as conductive material for energy-related applications.

Given the time constraints of the project, we will focus our efforts upon creating the finished nanofibers. If time allows, Nick and I will implement this into an energy application such as a capacitor. We then can compare how the nanofibers improve the performance of a capacitor, as opposed to the typical film inserted between the two electrical conductors of a normal capacitor.

Through working in an external lab, we have been able to learn the basic techniques of electrospinning and calcination. This process was simple, but had several steps that required a thorough attention to detail. For example measuring out the polymer solution to be used, the electrospinning setup, and the calcination settings had to be carefully done in order to ensure optimal results.

The next step for us will be to learn and begin conducting performance analysis on calcinated carbon nanofibers!

-Matt Cameron and Nick Pescatore

Redesigning the Electrospinner (Week 2)

Last Wednesday, after our Engineering Lab, we received the K'Nex pieces we needed to begin building the original design of the electrospinner, shown below:

The major design components that we wish to modify and optimize are:

• the collection area and the height of the collector
• the tray and grounding wire
• distance between gears

Since then, Nikita and I have been focusing on the height and collector component of the electrospinner. The first thing we did was redesign how the copper mesh (which we are using to collect the nanofibers) is held up. We created a holder (shown below) with one side open, in order to allow the nanofibers to land on the mesh without any interference. This assembly can be removed easily from the poles of the electrospinner, allowing the nanofibers to be easily removed. Also, should the copper mesh need to be replaced, the blue rods can be removed and the two pieces can be separated to easily remove the mesh.

The second thing we redesigned was how the collector was held in place. What we used was a simple bracket coming up from the base and held stable by the two bars next to it. The collector would simple rest on this. The yellow bars can be replaced should the height of the collector need to be changed.

The only other change we made was a minor one, in which we raised the base of the electrospinner to allow easier access to the tray that would be underneath it, as well as to make replacing any parts easier.