Tensiometer and Dissertation Defense

We arrived early to set up the 0.12% solution for three tensiometer readings. The first result is 40, the second run gave us 44, and the third run gave us 42. Jiangshui then suggested that we determine the surface tension of a 3% sample. This seems to be quite a jump in concentration, but he wants us to see that there is a limit to the effect of surfactant concentration on the surface tension of water. We will investigate both .30% and 3%. At 10 am we attend the dissertation defense of Edwin P. Chan, a member of Dr. A. Crosby's group. This is Mr. Chan's fourth year; upon receipt of his degree today, he will do postdoctoral work at M.I.T.. His dissertation, "Adhesion of Patterned Polymer Interfaces", was inspired by nature; specifically the ability of beetles, bugs, and geckos to climb up walls. Edwin compares adhesion using a single smooth surface to a surface with a patterned series of posts, then he varies the size, number, and shape of the posts to see the effects of these changes on adhesion. After this work was concluded, he determined that the establishment of these patterns was both labor intensive and expensive, so he sought another means to establish a pattern of adhesion posts. He then investigated wrinkling. He was able to establish a relationship between wrinkling pattern, pattern orientation, and the area being subjected to the stress that causes wrinkling. This provides a quick, inexpensive, and simple way to affect adhesion. After about an hour, it was not Mr. Chan anymore, it was Dr. Chan, he had been awarded his PhD. Congratulations!!
We returned to the lab to set up another reading for the 0.12% solution, then went to lunch. The usual Friday fare was followed by a 4th year PhD candidate's explanation of her work. Liz is a graduate of Carnegie-Mellon with a degree in Chemistry. She is working on nanoparticles for drug delivery systems, concentrating on the use of gold and PEG (polyethylene glycol) nanoparticles, which are amphiphilic and aggregate at an oil/water or nonpolar/polar liquid interface. We then returned to the lab to complete our work with the tensiometer.

Final entry for RET experience.

Some link and info:

Sabra's experience

Dave's experience

Lauren, Mary and Renee's experience

Thanks Go Out To:

Dr. Thomas P. Russell
Dr. Narayanan Menon
Dr. Greg Dabkowski
Jiangshui Huang
MRSEC
NSF
PSE staff and students
UMass - Amherst
Bill Brewer
Joe Alvarado

More Tensiometer!!

Just because I use exclamation points does not mean its a bad thing, its actually very interesting. Today was all tensiometer since we need to get data for each surfactant concentration and several readings for each. The 0.03% solution results from yesterday are 59, 60, and 61. We are satisfied that this surface tension is around 60. We then empty the 0.03% solution from the syringe, and rinse the syringe three times using the 0.06% solution. We then set up the tensiometer to take three readings on this solution, and the surface tension of the 0.06% solution was determined to be 50, 51.5, and 51, so the average surface tension is 51 for 0.06% surfactant solution. We will continue with the remaining solutions tomorrow.

AFM, Tensiometer and Dr. Menon

Today we were shown how the Atomic Force Microscope (AFM)works. This is one of the things I have enjoyed most being here, just seeing and sometimes using all the different devices I have ready about. We will not use this instrument, but Ji Xu explained the principles of its operation and how to use it. He was very helpful and did not mind all the questions I asked. :-)

The AFM is not optical; it has a tip (visible only using an optical microscope) that vibrates vertically in response to an oscillating voltage, so that in effect it gently taps, very gently, the surface of the sample at a constant amplitude as it moves along its surface. The constant amplitude of the tapping allows the tip to move up and down with the variations of the topography of the sample. The tip is attached to a cantilever which is just barely visible to the naked eye; this is attached to a black matrix that is large enough to be manipulated into position on the instrument. Prior to analyzing the sample, the AFM must be calibrated for that specific sample. First, the tip size is selected; the smaller the tip, the higher the possible magnification. Resolution is determined by the number of oscillations, or vibrations, of the tip on the sample surface, and magnification is again affected by the amplitude of the oscillation of the tip.

A laser beam shines down onto the cantilever and, as the tip moves across the topography of the sample, the beam is reflected at different angles. The reflected laser is collected by receptors that are analyzed and interpreted by the computer to create images. Ji Xu has hexagons that self-assembled as his polymer annealed. A close up of one of the hexagons is seen below, from the AFM, the other picture shows the sample in an optical microscope, the hexagons are the tiny dots to the left of the large drop.


After lunch, we then set up the Tensiometer to measure the surface tension of the 0.03% solution again.

At 2 pm we went with Jaingshui to meet with Dr. Menon of the physics department in Hasbrouck. The first discussion focused on our progress with wrinkling, use of the reflectometer, and data analysis with ImageJ and Origin software. We then discussed problems that we could encounter using the surfactant. The surfactant is amphipathic, and the polar tails actually stick up from the surface of the water, making the environment at the surface of the drop different from the drop's internal environment. The same is true in a bowl of water/surfactant solution: the hydrophobic tails of the surfactant stick up while the hydrophilic heads are oriented toward the water. In the rest of the water, the hydrophobic tails of the surfactant are attracted to one another and form mycellae. The mycellae eventually form spheres (head to head/tail to tail attraction). If the spheres are broken apart (agitation, heat) they may reassemble as cylinders. If the concentration of the surfactant continues to increase, and the cylinders are broken apart, then lamellae may form. The formation of these various structures is dictated by the general rule that material tries to form the geometrical shape with the smallest surface area relative to its concentration.

Jiangshui then discussed the next focus of his research with Menon. Jaingshui will be working to create experimental evidence to support the mathematical explanation for wrinkling patterns when a force, using a tip, is applied to the surface of the film.

Tensiometer and Surfactant solutions

Since we are relatively trained on using the Tensiometer, we will prepare solutions of differing surface tensions by using a 5% stock solution of Dodecylsulfate, Sodium salt. By we, I mean Sabra since I really don't want to deal with a syringe, since I know how clumsy I am. Sabra prepared 0.03%, 0.06%, 0.09%, 0.12%, and 1% solutions

We then set up the tensiometer to determine the surface tension of the water/surfactant solution. We let it run for about an hour. We received a surface tension reading of 61.

After lunch was the Russell group weekly meeting. Dr. Russell set the sequence of presentations, then spoke with individual group members about their progress, expenditures, and references. He spoke with some of the newer PhD candidates about the upcoming cumes. First and second year PhD candidates must take exams (cumes) as part of their program. The exams are offered on the second Saturday of the even numbered months, and consist of six questions; two chemistry, two physics, and two engineering based. PhD students must answer four of the six questions at each session. The students must pass four Cumes in a row, or five total.

Tensiometer

So far we have been wrinkling with water as our base liquid, which is what the film floats on, and with water as the liquid for the drops. Now we will be wrinkling with solutions of different surface tensions, which will be water but with differing amounts of surfactant. Remember surfactants decrease the surface tension. The normal surface tension of water is 72 mN/m (milliNewton per meter). We will determine the surface tension using a device, the Tensiometer, which measures the surface tension of a liquid based on a drop of the liquid.
First, we need to learn how to set up the Tensiometer. This instrument has a precise set up regimen. After turning the instrument on, a microsyringe is filled with the solution to be analyzed. Then the syringe is inserted into the syringe holder, just to the right of the thermometer. A cuvette has one ml of water added to it, then it is covered with parafilm. A hole is cut into the parafilm so that the tip of the syringe can be inserted into the covered cuvette; all this is done to prevent evaporation of water from the surface of the drop being analyzed during the measuring period and it reduces any disturbance from the air hitting the drop. It is critical that the syringe is precisely perpendicular to the water surface, and that the drop is as large as possible without falling off the tip of the syringe.


As is true of every instrument we have encountered in the lab, the Tensiometer is computer driven. The software, SCA20, is initiated and the parameters for the system and for the ambient conditions are entered into the computer. Once the program is set, the computer directs the volumes to be dispensed from the syringe to create the drop to be analyzed.
The data is recorded for at least 30 minutes since it takes some time for the drop to become stable, so the first ten to fifteen minutes of readings are discarded. The readings then become stable and are displayed alphanumerically as well as graphically.
At the end of the day, we attended a seminar presented by two professors from Tsinghua University in Beijing, considered China's M.I.T., which has a total enrollment of 30,000 students. Dr. Quingling Feng presented her work on :The Fabrication and Characterization of Scaffolds for Tissue Engineering", which explained the use of biomimetic composites to encourage bone growth. The biomimetric composites are based on studies of natural bone; nanohydroxyapatite/collagen can be molded on PLLA to create a bone scaffold very similar in structure to naural bone. In some work, chitin was used instead of hydroxyapatite in conjuncton with the collagen, and more crosslinking between molecules (therefore higher compression strength) was found. A combination of the two polymers was used to repair fractures in goat tibia, and the healing time was decreased. The material has received approval for trials in humans in China. The second presentation was by Professor Guosheng Gai, whose field of expertise is the behavior of fine powders. His current research investigates the construction of composite particles and modification of their shape. He controls the microstructure within the material to affect particle shape. He has been able to create conductie plastics through particle coating. This was hard for me to follow.

X-Ray, Wrinkling Analysis and Presentations

We arrived at Conte by 7:30. Today was going to be used to check out our hypothesis about different thicknesses. We made several films and I set up the X-Ray Reflectometer.
The data was just OK...we only got three consistent waves in a row, and there should be five in a row to get a good measurement of film thickness. We calculated the thickness to be about 100 nm thick, which is thicker than either Jaingshui or Dave get ( about 86 nm). The second slide was processed, but this time we got no usable data, the specimen may have been in backwards, so there was no film on the slide
The normal Friday noon lunch for R.E.T.s (us) and R.E.U.s (undergrads doing research) was held, followed by two presentations by doctoral candidates. Kate was first to present; working with the Lesser group on improving the environmental resistance of PBO. PBO replaced Kevlar as the primary constituent of bullet-proof gear because it has a higher tensile strength than Kevlar and is lighter in weight and simpler and less expensive to produce. It has failed, however, after prolonged exposure to UV light and moisture. The project is hoping to develop a polymer to coat the PBO that will confer UV and moisture resistance to the substance without reducing tensile strength.The second presentation, by Simon, was entitled "Novel Hybrid Polymers Incorporating Carboranes as Pendant Groups". These structures are used in Boron Neutron Capture Therapy; the structures are incorporated into tumor tissues then bombarded with neutrons. The result is site specific, isolated radiation therapy.
The remainder of the day was spent measuring thicknesses of films and measuring wrinkle patterns obtained on Thursday.

Birthday

Still need to catch up on blog but today I needed to celebrate my Birthday. Darn, I am getting old but that is the way it goes :-)

Here are some pics of celebrating my birthday with my friends here at UMass.

Thanks again for the cake Sabra. Thanks Dave. Thanks to Greg and all the students that wished me a Happy Birthday. It was bad being away from home but I was able to celebrate a little.

Saran Wrap, X'Pert Pro and More Wrinkling

For the last couple of days, Jiangshui, Sabra, Dave and I had been discussing how we could bring these experiences with wrinkling into the classroom. Today we tried what we thought would be a good idea. Saran Wrap! Its a film, sort of thin, could float on water. I am including a picture (for educational purposes) in case anyone has not seen this wondrous product.Sabra brought some from home. We got a large glass container to hold the water. Jiangshui cut out a piece, kind of circular, and placed on top of the water. The saran wrap floated. That worked, next, we used a pipette to place a drop of water on the saran wrap. Success? Nope, failure. No wrinkles. Added more water, still no wrinkles. Added more ....... No success. We decided that the saran wrap is too think. Tried parafilm. Did not work. Tried glue between slides. Just came apart, no film developed. It seems that the film must be a nanostructure. Sabra thought of the film that develops on top of pudding or scaled milk. We will keep thinking about it. Remember though, just because they were failures was not bad, it helped us figure out possibly why.

For the rest of the day, we worked on floating films for wrinkling and placed a slide for x-ray reflectivity.
We made the films by spin coating.

The floating went well. Took lots of pictures since we did three slides a piece. None of us had any problems with the films today and we did them a lot faster. All the practice has helped us get better at this procedure

We went back to check the results from the x-ray reflectivity analysis. The film was ~100 nm. This is a bit higher than the other films and higher than Jiangshui's. When we compare these readings to what we have done before and to the number of wrinkles, we seem to be getting a trend of Dave's films have a lower thickness, Sabra's have a higher thickness, and mine fall somewhere in between. This could account for the difference in the number of wrinkles. Since we have taken turns on whose slide get analyzed, we have not kept track if we are being consistent on our own slides. We have decided for tomorrow to show up early so we can do at least two slides in a row for each of us to see if we are each dealing with different thicknesses. This difference could be due to our own way of making the film. ** Scientific Method at Work **

More Practice and Filmetrics Interferometer

Today, we were going to practice more on floating of the PS films and checking the thickness of the films. We are going to learn how to use the Filmetrics Interferometer.
Everyone made two films for wrinkling analysis at Hasbrouck. An additional slide was made for X-ray reflectivity. We set up the X'Pert Pro for analysis for the thickness of the film. We made a quick video on placing the slide on the stage. As you can see, it takes a couple of tries sometimes for it to close correctly and then it must be raised or lowered, using a screwdriver, to get the proper count rate to start the analysis.

We left it running and went to Hasbrouck to perform the wrinkling.

We went through the usual procedure. Cut out film, float film, add 2 microliters to the center, take picture of whole film and zoom it and take picture of wrinkles. Go through all the increments and take pictures at each one. Each of us did our films, I messed up on one. When moving the film towards the middle to take the picture, I touch the top of the film instead of the side and it created wrinkles all over the film so I could not continuing using it. This is why we, or I, need practice on this procedure. Save the pictures of analysis.

In the afternoon, Ling Yang showed us how to use the Filmetrics Interferometer. This instrument uses reflection of light directed at the film so the light must bounce back. This would not happen if we used a glass slide so we used a piece of silicion sheet instead as our substrate. We broke off a piece of silicon and spin coated, at a slower speed since the interferometer needs a thicker film to analyze.

Once spin coated, we took it to the room with the interferometer but that one was not working so Ling Yang took us to her interferometer set up. She demonstrated how to calibrate the Filmetrics interferometer and how to focus the light. This is required to acquire accurate readings.


The thickness range for the Filmetrics is between 30 nm to 1mL which would be adequate for our thickness readings on our films. But, there is always a but, the X'Pert Pro gives much more accurate readings for thickness. And since were are comparing wrinkles and thickness, we want the most accurate readings possible.

Thesis Defense, Image-J/Excel and Group Meeting

We started the day by going to a thesis defense. Richard Woudenberg presented Anhydrous Proton Conducting Materials for Use in High Temperature Polymer Electrolyte Membrane Fuel Cells. As I understood it, he works for the Marken corporation and was given time and support to get his PhD. He talked about developing materials that did not require water, anhydrous, to function. He mentioned work on polymer electrolyte membrane fuel cells. Some of the other stuff he mentioned was a bit over my head. But I need to say, it was very interesting to see someone going through this process and seeing what they had to do.

After that, we went to the Russell Group computer room and started analyzing the pictures from the wrinkling. We opened up the pictures using Image-J to get the pixel areas of the whole film, of the water drop, of the wrinkles, of the water drop again, the zoomed in picture, and the number of wrinkles. Once we had the areas, we used Origin or Excel to analyze the data to determine the diameter of the water droplets and the length of the wrinkles.

After lunch, we attended the group meeting for the Russell Group. These are the students, working on their PhD's, and post-docs working with Dr. Russell.

Other people that are not in this picture: Ji Xu - Sivakumar Nagarajan - Narupol Intasanta

During the meeting, which are usually held weekly, some of the individuals were called on to give a talk on an assigned published paper. The individual must describe what the experiment or idea is and give their opinion on it. Dr. Russell asks specific questions to either check what was on the paper or to force the individual to think what can be done with this information. Other individuals gave a presentation on the progress of their current research. Another experience into what is involved in attaining a PhD. Quite Fascinating.

Wrinkling, X-Rays and Dr. Russell

Started off the day setting up threes slides. One was set up for X-ray reflectivity. We set up the X'Pert Pro. Since it takes 1.5 hours, we left it running and went to Hasbrouck to do the wrinkling. We are getting more proficient at the wrinkling procedure. We are becoming faster at adding the 0.2 microliter incremental amounts and at taking the pictures of the film and of the wrinkles. Each one of us did two films with the given amounts of water and the pictures at each point and transferred the pictures to the computer. We will analyze the pictures later.

Met with Dr. Russell today. We discussed what we have done over the last two weeks. We mentioned all the instruments we have been trained on, the spin coating procedure and the wrinkling procedure. He talked about how the x-ray reflectivity worked and related it to the colors seen on the surface of the bubble, same as an oil slick on water. They both show colors based on constructive interference, destructive interference and index of refraction which can be used to determine the thickness of the "film."

We went to look at the data from the X'Pert. The data looked good once it was set to a logarithmic scale. It showed the peaks and the troughs that we needed in order to calculate the thickness of our film.

We got the necessary data from the troughs and calculated, using Excel, the thickness of the film. It came out to 98.133 nm, which is a bit thicker than we should have gotten.

We spin coated two more slides and took them to Hasbrouck to do the wrinkling on them. We have lots of pictures so we will need to start analyzing them soon. For now, we want to make sure we can do the procedures and that we do them well. Practice, Practice, Practice. :-)

SEM (very cool), Lecture, Current Research and Wrinkling

The day started off with Dian, one of the PhD candidates, showed us how to use the Scanning Electron Microscope (SEM). In the morning, we went to one of the microscopy rooms. This room held the Transmission Electron Microscope (TEM) and the Scanning Electron Microscope (SEM). Dian first showed us around the room. She then started setting up the sample to be coated with gold. Samples must be coated with either gold or platinum so that they conduct electrons and so the SEM doesn't destroy it during the analysis. The sample is set up on a metal base and carbon tape. This way the sample is set up to conduct during its use on the SEM.

Once coated, the sample is ready to be placed in the SEM (pictures of the sputter coater are in Sabra's pictures link Dian placed the sample in the SEM and we were able to see the sample and zoom in on it to see the nanotubes.

Dian showed us how to use the SEM and then each one of us had a chance to use it on a new part of the sample. Dian is trying to determine the thickness of the nanotubes and the roughness the exterior.


After working with the SEM, we went to another lecture by Dr. T. Hashimoto. In this lecture, he talked about how carbon black affects polymerization. The research was using the same scattering techniques that he talked about yesterday. And that is about all I really understood. :-) Just a bit over my head on these discussions. After that, it was time for the Friday Talks/Lunch. The talks were given by two PhD candidates and it was about their current research.

Chris talked about his work in photovoltaic cells (solar cells) but using organic substances. Since its organic, it would make the cells much less expensive which is one of the problems with solar cells. Since they are nanostructures, it may make them more efficient which is another problem for solar cells. Andrew talked his attempts of getting polymers to self heal. Just like when we cut ourselves, our skin repairs itself. The group Andrew is in is trying to figure a set up where polymers can repair themselves. There are quite a few ideas on how polymers could do this.

In the afternoon, we set up more slides. One for X-ray analysis and the others for wrinkling practice. We need quite a bit of practice doing this; it is very precise work. Practice makes perfect.

Analyzing with Image-J & Origin, Lecture and X-Rays

We started off the day by analyzing the pictures of the wrinkles. Image-J is used to determine pixel areas of the whole film, water droplet, wrinkle film and water droplet at different magnifications. Origin takes this data and sets up a ratio between the areas and then by comparing it to the known diameter of the film is able to calculate the length of the wrinkles. The wrinkle length is one of the parameters we wish to calculate. The other parameter is the number of wrinkles. We still use Image-J, but just to zoom in, and we manually have to count the wrinkles. Like I mentioned, Image-J is on the Internet for free but not Origin so I converted the formulas from Origin to Excel. This way I can do the analysis at the dorms, if I need to.
Around lunch time, Dr. T. Hashimoto from the Japan Atomic Energy Agency in the Advanced Science Research Center gave a quick lecture on ..... (look at the pictures below)

The first picture is for the title of the lecture and the second picture shows some of the methods used for the analysis of the samples. One of the main things he was talking about was how the cellulose nanostructures look very similar to the smoke coming out of volcanoes. So it seems that when the cellulose self assembles it follows some physical behavior that may be inherent in all substances. The rest of the lecture was interesting especially types of scattering used for analysis.
The rest of the afternoon we continued analyzing the wrinkles with Image-J and Origin and we set up a sample for X-ray reflectivity. The film had a thickness of 93.895 nm.

Spin Coating and Wrinkles

We will work on setting up the slides by spin coating and then going to the Hasbrouck building, since that is where the microscope is set up, to take pictures of the film and the wrinkles.
Placed three large petri dishes in the hood, they will hold the finished slides. Placed several weighing papers inside on the bottom to keep the slides from getting contaminated. Each petri dish will hold the three slides that each one of us will make. I made my slides by the usual procedure: clean surface of spin coater, place slide on spin coater, set speed to 1200 RPM, clean slide with acetone, spin to remove acetone, place solution on slide, spin to coat slide, remove and place in petri dish. Once I was done will all three, I covered the petri dish, this is to prevent contamination here and on our way to Hasbrouck. Sabra and David prepared their slides.
We walked over to the Habrouck building since that is where the instruments are set up to take the pictures of the wrinkles.

We then set up the slide so we could score the size of the film we wish to float onto the water.

We then floated the film onto the water and started the wrinkling by adding tiny amounts of water,2 mL at a time and taking pictures.


During each addition of water, we took picture of the overall film and a picture zoomed in on the drop and the wrinkles it created. The pictures were then analyzed using the Image-J program, for areas, and then the Origin program, for numerical analysis.

For more pictures of the process, check the pictures link on the upper right hand of blog.

X-Rays and Another Method of Determining Film Thickness

Still about a week behind. Sorry. Though, I have been working :-) I had to set up my new website for the school I am moving to. And learned how to use Picasa for the pictures I am using on the blogger. Also found the site for the software we use to analyze the wrinkles, its free. Anyways, let me continue on the blog.

Today, we will use the X'Pert to detemine the thinkness of more film samples that we set up. We followed the same procedures as before: set up the spin coater, prepared the slide by cleaning with acetone, set up the correct speed for the spin coater, applied solution and started spin coater, if the film looks good, take to X'Pert room. Jiangshui allowed us to try it on our own, with him watching us. I really feel like a scientist at these times. We each tried it. We started up the X'Pert, put in the required settings for thickness analysis, set up the required componts, started X'Pert to detemine the "blank" and correct peak settings, placed slide in the X'Pert, set to required count rate and began analysis. Will take 1.5 hours so we went to explore another method of determing film thickness.

The other method requires a Profilometer and a cut on the film. This device actually places a very small needle, the stylus, on the surface of the film. The needle moves across the surface and then drops into the cut and then comes back up. By analyzing the readings from the normal surface height and the height of the cut, the computer can determine the thickness of the film.



This is a great device for deteming thickness since it is very easy to use. The only problem is that the film must be at least 1 micron or micrometer ( mm) and our films are ~90 nm which is ten times smaller than what can be used by the Profilometer. Because of this limitation we can't use it on the films we are working on so we made an extra one but it was made by dissolving a styrofoam cup in toluene. We let it dissolve for about an hour while we were doing the x-ray reflctivity and then did the spin coating with it. After setting up the profilometer and adjusting the stylus (see picture above). We started the device and collected the data. The data must be standardized and then the comparison is done. The film was about 1.36 microns ( mm) .

Even though we will not be using the profilometer, it was an experience to work with it. Remember it is called the Research Experience for Teachers so we are learning and experiencing all we can in the lab. Later on we will get to see how a scanning electron microscope works and other instruments along the way. We went back to the X'Pert and looked at our data on the computer and calculated the thickness to be 93.478 nm.