2009 Exam

CHEM 400 Exam – Advanced Polymer Topics – 2009
Time allowed: 24 hours
Due back: 9 am Monday July 13th 2009
Work independently of your fellow Honours students.
Otherwise, you may use any resource available anywhere in the world, but must cite all resources used.

Part One. Answer all questions associated with any six of the nine papers below. (60%)

1. Structure and Properties of Composite Antibacterial PET Fibers
Wang Shuhua, Hou Wensheng, Wei Liqiao, Dai Jinming, Jia Husheng, Liu Xuguang, Xu Bingshe
These researchers work in Taiyuan, a city a visiting academic we had at the University of Sydney once proudly told me was the most polluted in the world.

What should the units of tensile strength be in Table III? Explain how these values were measured and why they might show the trend they do with loading of silica nanoparticles.
What is the double refraction index, Δn? Why should it show a positive correlation to break strength and a negative correlation to extensibility? Explain how the Δn results are consistent/inconsistent with the X-ray diffraction and tensile strength results.
As a scientist interested in polymers and colloids, what is one additional experiment you would have done before publishing this work?


2. The Furan Counterpart of Poly(ethylene terephthalate): An Alternative Material Based on Renewable Resources
Alessandro Gandini, Armando J. D. Silvestre, Carlos Pascoal Neto, Andreia F. Sousa, Mónica Gomes
I have never heard of Aveiro, where the University of Aveiro appears to be located. Has anything interesting ever happened there? Is there anyone famous who comes from Aveiro?

Explain the necessity for ‘concurrent trapping of the released ethylene glycol at liquid nitrogen temperature’.
Explain what is physically happening at the ‘crystallisation isotherm’ in Figure 3.
The authors have explained the origin of the broad background signal in PEF after quenching in Figure 4, but why do you think there are more sharp peaks in the X-ray diffractogram of PEF after quenching than before quenching? Explain and identify the peaks as fully as you can.
As a scientist interested in polymers, what is one additional experiment you would have done before publishing this work?



3. Polygalactose Containing Nanocages: The RAFT Process for the Synthesis of Hollow Sugar Balls
S. R. Simon Ting, Andrew M. Gregory, and Martina H. Stenzel
I applied for a job with this group just around Christmas 2003, but UNSW had put the wrong email address in the advertisement so it bounced back. It was the last day, and for whatever reason- there was some technical glitch or other- I decided ‘stuff it’ and didn’t send the application again.

Explain, with reference to as many chemical structures of RAFT intermediates as are relevant, why the slopes of the three curves in Figure 1 are different and why the induction times before they start are different.
How does the Brookhaven Zetaplus particle determine hydrodynamic diameter? What is hydrodynamic diameter, anyway?
If one of your students was using SEC traces like the ones shown in this paper to calculate polydispersity, what would you say to them?


4. Plasticization of Zein: A Thermomechanical, FTIR, and Dielectric Study
Thomas Gillgren, Susan A. Barker, Peter S. Belton, Dominique M. R. Georget, and Mats Stading
Steve had some students from Gothenburg come and work with him some years ago. As late as the 17th century, Norwich was the second largest city in England. But I don’t really know anything about either of those places.

What do you think is going on with the (lack of) plasticisation by mercaptoethanol in these experiments?
Explain what complex permittivity is and what is going on in Figures 8 and 9. Use as many equations as you have to!
What is Maxwell-Wagner dispersion? Suggest one other experiment that might be done to check for the presence of bulk water in these systems.


5. Exploring the Liquid-like Layer on the Ice Surface
M. P. Goertz, X.-Y. Zhu, and J. E. Houston
When I was young we used to live near Minneapolis. I used to have to walk a mile in the snow to catch the school bus. I was in two school bus accidents where we slid off the icy road into ditches. I think we might have got a different school bus driver after the second one.

What do you see as the most significant experimental uncertainties hanging over this work?
Suggest an explanation for the abnormally high viscosity value for the liquid like layer given by the Feibelman equation. Is this viscosity consistent with the macroscopic properties of ice?
Explain what is going on in Figure 3(b). Is the statement ‘the accurate characterization of this “frustrated-capillary” behavior involves a rather sophisticated hydrodynamic model and is certainly beyond the scope of this contribution’ just a hand-waving cop-out, or what?
As a scientist interested in messing about with ice, what is one additional experiment you would have done before publishing this work?


6. Assembly of Self-Assembled Monolayer-Coated Al2O3 on TiO2 Thin Films for the Fabrication of Renewable Superhydrophobic-Superhydrophilic Structures
Shunsuke Nishimoto, Hitomi Sekine, Xintong Zhang, Zhaoyue Liu, Kazuya Nakata, Taketoshi Murakami, Yoshihiro Koide, and Akira Fujishima
I know this guy from uni in Townsville who worked in admin at UTS for a while and then met a Japanese girl and moved to somewhere in greater Tokyo- which probably isn’t actually anywhere near where these guys work. The girlfriend he had before the Japanese girl didn’t like this giant paper mache dog he had that apparently used to hang from the ceiling in a nightclub in Perth, so I said I would take it and it currently takes up a lot of space in my dining room.

What is the significance of the following result: ‘(advancing CA: 167°; receding CA: 152°; CA hysteresis: 15°). Specifically, why is contact angle hysteresis important?
Can you find any experimental justification out there for the assertion that superhydrophilicity is lost due to adsorption of hydrocarbons from the atmosphere? If so, outline the experimental results that have been obtained. If not, suggest an alternative explanation for the loss of superhydrophilicity over time.
What is the point of fluid microchips? Will they change the world? If so, how?


7. Complex Micelles Formed from Two Diblock Copolymers for Applications in Controlled Drug Release
Guiying Li, Lei Guo, Songmei Ma, Junshen Liu
Can’t remember if I ever told you my anecdote about Yantai or not. Just in case, I won’t bore you with it a second time.

Explain the results shown in Figure 7, explaining why the release profiles are the way they are for the different complex micelles.
What is a Janus-micelle? Is it really accurate to call such a thing a micelle?
If you had done this work, how would you have reported the polymer characterisation results differently? What additional information would you have presented and what methods would you have used to get this information?


8. Pattern Formation in PMMA Film Induced by Electric Field
Oleksiy Lyutakov, Ivan Hüttel, Václav Prajzler, Vítěslav Jeřábek, Alexander Jančárek, Vladimír Hnatowicz, Václav Švorčík
How are you supposed to pronounce an ‘ě’, anyhow?

Explain how the different channel profiles obtained in Figure 3 and Figure 6 might arise.
This paper reports primarily on the characterisation of the surface of the PMMA films. What differences might you expect to find in the bulk film between patterned and unpatterned films, and what characterisation methods would you employ to observe these?
The work reported here seems to have certain similarities with ‘electrospinning’. What is electrospinning? What do you expect might have happened if the researchers had just kept cranking up the electric field?


9. Preparation and Characterization of Multiwalled Carbon Nanotube Dispersions in Polypropylene: Melt Mixing Versus Solid-State Shear Pulverization
Saswati Pujari, Thillaiyan Ramanathan, Kosmas Kasimiatis, Jun’ichi Masuda, Rodney Andrews, John M. Torkelson, Catherine Brinson, Wesley R. Burghardt
There was a chemist at USyd whose name I can’t remember right now who got his PhD at Northwestern, he looked like King Henry VIII on graduation days, it was the most fantastically opulent male garment I have ever seen outside of the movies.

In Figure 7, what is q? What is the main thing the figure telling us, and why/how does this work? What information might be theoretically obtainable from the parts of the curve at extreme left and extreme right?
What is the storage modulus, G'? How is the frequency dependence of G' related to chain entanglements? Explain what is going on at the molecular level to give the results shown in Figure 2.
As a scientist interested in why the mechanical and electrical properties are different for the two different methods of dispersing carbon nanotubes, what is one additional experiment you would have done before publishing this work?

 
Part Two: Answer all questions associated with any three of the six papers below. (25%)


10. Stabilization of Enzymes in Silk Films
Shenzhou Lu, Xiaoqin Wang, Qiang Lu, Xiao Hu, Neha Uppal, Fiorenzo G. Omenetto, and David L. Kaplan

With most biological materials, the higher the water content, the more rapid degradation processes can occur. In this work, however, the trend is the opposite way around. Why is this?
Pretend you are one of those lame science-fiction writers of the old school who puts in big blocks of exposition explaining the new technology postulated in the story. Write a paragraph of exposition describing a gee-whiz technical innovation based on the research in this paper and explaining how it works for the folks at home.


11. Non-cytotoxic Silver Nanoparticle-Polysaccharide Nanocomposites with Antimicrobial Activity
Andrea Travan, Chiara Pelillo, Ivan Donati, Eleonora Marsich, Monica Benincasa, Tommaso Scarpa, Sabrina Semeraro, Gianluca Turco, Renato Gennaro, and Sergio Paoletti

What is a “surface plasmon resonance band”? I am sure I have had it explained to me a number of times but it has never sunk in properly, so use small easy words.
Do the results in this paper fully assuage any fears you might have about the cytotoxicity of silver nanoparticles? Suggest some additional experimental tests to reassure yourself (if you answered no), or some timid people you know (if you answered yes), that might be worth trying before you licensed this technology for commercial applications.


12. Inactivation of Bacterial Pathogens by Carbon Nanotubes in Suspensions
L. Renea Arias and Liju Yang

Outline the different results obtained for inactivation of bacterial pathogens by SNTs chemically-modified in different ways. How do the authors explain these differences, and the differences between SWNTs and MWNTs? Can you think of any other possibilities to explain the differences?
In chemical terms, what is the difference between Gram-positive and Gram-negative bacteria? How do these chemical differences relate to the environments where these bacteria might be found?


13. Using the Flotation of a Single Sphere to Measure and Model Capillary Forces
C. W. Extrand, and Sung In Moon

An old and wise scientist I know once (well, often) told me: ‘Just because the model fits the data, it doesn’t mean the model is true.’ Is there anything important left out of the model given that really should be there to give a complete physical picture of what is going on? Is there anything included that doesn’t make a great difference to the predictions obtained but makes the equations much more complicated?
What does the model predict Rmax to be for a PTFE sphere in water with a surface modified to be superhydrophobic?


14. Design of Surface Hierarchy for Extreme Hydrophobicity
Yongjoo Kwon, Neelesh Patankar, Junkyu Choi, and Junghoon Lee

You have probably heard of SNU in connection with ‘Snuppy’, the first cloned dog.
This paper talks quite a lot about the transition between the Wenzel state and the Cassie state. What are these states?
Most of our encounters of superhydrophobicity have discussed plane surfaces. What are some potential applications of superhydrophobicity to fibres, and what are some of the pitfalls that we might need to watch out for in trying to achieve these applications?


15. Innovative Approach for Producing Injectable, Biodegradable Materials Using Chitooligosaccharides and Green Chemistry
Luciano F. Boesel, Rui L. Reis and Julio San Román
My only connection with this group is that I cited them once.
To what extent do you think the products discussed in this paper are actually ‘biodegradable’? To what extent do you think the chemistry is actually ‘green’? Naturally, justify your assertions.
Tell me all about MALDI-TOF and its application to polymers. How is it different from other mass spectrometry techniques?


Part Three (15%)

And finally...
Of all the papers we have read this semester, which line of research would you be most interested in investigating further is someone gave you $5 million to continue on from one of them? What major questions would you seek to answer and what experiments would you initially carry out to work toward answering these questions?