Two Birds with One Stone (Wk 3 S16)

Rumors have been circling about how I didn’t do a wupdate last week and I’d like to address the issue head on: I will provide a wupdate on not just my work from week 3, but week 2’s work as well. Double the fun in half the time. I know, ambitious.

During week two, I spent part of my time making the figures for the paper. Initially, I did a rough version of them because I was a little too excited to get to the paragraph writing. In retrospect, it would have saved me some time to just make them #flawless, but ya live & ya learn I guess. Additionally, I made a table of the extracted Ea’s for the IL family members. Each family member has an Ea resulting from the SAE and 2 resulting from the CAE (slope & intercept). These Ea’s were compiled in the table and each was plotted as a function of alkyl chain length. The plot of SAE Ea’s as a function of alkyl chain length looked like ln(x) in shape, steadily increasing with the rate of change slowly decreasing. The range of these Ea’s was about 7 kJ/mol.  Meanwhile, the slopes & intercepts looked like a “right-skewed bump” when plotted as a function of alkyl chain length. These Ea’s had a range of about 2 kJ/mol, which is significantly smaller than the SAE. It is also worth noting that the slope Ea (CAE) is lower than the intercept Ea (CAE) for both the cation & anion at alkyl chain lengths of 3 and 8, but the opposite is true for lengths 4, 5, and 6. Lastly, the magnitudes of the cation slope/intercept Ea’s were about 2 kJ/mol larger than the corresponding anion diffusion Ea’s for all alkyl chain lengths. On the other hand, the SAE showed differences of about 0.5 kJ/mol, with the anion being consistently larger than the cation (opposite trend).

The other part of my time was spent reading through about 10 papers to see how the scaling procedure was presented, among other things. I mostly took note of what I liked/didn’t like and tried to summarize how the information was being presented. From there, I made an outline of how I wanted to present the data, results, and scaling procedure. I drew it all out on the blackboard in the research office (picture attached).


During one of our meetings this week, Allison ran me through the theory paper, which was something I’d been meaning to get to because as I wrote on the blackboard, the theory paper should help me explain some of the parts that I still need help understanding. We also talked about how we know when the CAF “works” and when something follows “Arrhenius behavior” because the R^2 value of ln(D) or ln(D/D_r) doesn’t seem to be a very strong qualifier.

Finally, I’ll touch on the aims of the paper in general and how I am working toward those which are much broader goals.

There are somewhere between 3 and 4 goals of the IL Diffusion paper and they are:

  1. Diffusion coefficients for ILs can be modeled using the CAF. A corollary to this is being able to justify applying Onsager’s model to associating liquids, which allows us to utilize the dipole density, N(T)/T, to represent the polarizability of the molecules instead of the static dielectric constant, epsilon_s.

    Currently, I’m working to achieve this goal with the master curves of the diffusion coefficients for the anion and cation. There are some quirks to the master curves, but the bottom line is the CAF works. I’m putting this aspect of the paper into words as we speak and I have a pretty solid draft right now that goes from the initial D as a function of N(T)/T plot down to the table of energies of activation I mentioned earlier. The point of the table being that if the CAF works, the energies of activation will be significantly different (and they are). What I still have to write is the story from the analysis of the table to the master plots they ultimately form. Segue!

  2. Comparison of cation diffusion coefficients and anion diffusion coefficients: what in the Ea is going on??

    Once I have the master curves sufficiently analyzed, I’m going to be comparing both the Ea’s they produce (Cat = 47.4 kJ/mol, An = 44.8 kJ/mol) and the functional form of the exponential prefactor (which as of right now, they look identical).

  3. Comparison of diffusion data to the conducitivity and fluidity data for TMAA-TFSA IL.

    I think this aim should be addressed after the analysis of the spectroscopy data because the purpose of Chris’s data is to help try to explain the differences in the Ea’s of the cation and the anion. In a perfect world, we will be able to account for the differences between the Ea’s and then show the similarities between the conductivity (avg of 46.9 kJ/mol) and the diffusion Ea as a precursor to the claim that diffusion of a cation/anion in an IL is synonymous with charge transport (conductivity) in ILs.

    Either way, the figures for this have already been made so the analysis is what remains.

  4. Spectroscopic Data

    I think I’ll let the trained Ph.D. spectroscopists (CMB & AMF) handle this one… Ooh! I’m not totally benched on this one, though, because Allison gave me a paper on spectroscopy to read (hurray!)

That’s all for now. Happy Sunday! P.S this thing is SO cool.





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