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:
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
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