Concern over the 1:10 LiTf:C4mPyrrTf solution solubility (Mon. July 27 & Tues 28th 2016)-
Professor Fleshman has expressed serious concern that 1:10 (moles solute: moles solvent) of lithium triflate will not fully dissociate in N-butyl-N-methylpyrrolidinium triflate, or that solutions with larger alkyl chains at lower temperatures, required for the CAF’s traditional temperature regime of 5-85˚C, will precipitate lithium salt. This concern was brought about due to her observation of her 1:10 LiTf C4mPyrrTf solutions from a year ago that were cloudy and had small amount of crystals. It has been noted that the 1:10 Na and K triflate solutions were not cloudy nor was any precipitate observable (it is good to note that we have been told MgTf is completely insoluble by Allison’s Colleague). Although the use of NaTf and KTf may seem like a clear alternative, Professor Fleshman wishes to use some of our initial data to apply, with several of her colleagues, for a NSF grant. Given the recent interest in using lithium salts dissolved in RTILs for lithium batteries this guise of our research being useful for lithium batteries is essential for receiving funding from the NSF, so NaTf and KTf may be just as useful for our research into the CAF, but for now it is essential that we use LiTf. Although we were able to find some information on dissolving LiTf into imidazolium triflate (see the report from last week) we have found nothing on the dissolution of LiTf into pyrrolidinium triflate, although it is important to note that doping LiTFSI into pyrrolidinium TFSI is quite common. Currently Allison is waiting to hear back from Chris about whether us using a 1:20 solution of LiTf:C4mPyrrTf would work with his research. Hopefully this means we will begin preparing a solution tomorrow, but I have significant doubts. I imagine that we are in delay until more C4mPyrrTf is ordered and shipped, which Allison estimates to take about one work week. Until then I am to study Chapter 20 from Atkins about Molecular Motion.
Triflate to TFSI (Wed. 29th 2016)-
We have finally decided on the using the N-alkyl-N-methylpyrrodinium TFSI RTIL as are solvent and LiTFSI as our solute. This decision came after Allison talked to her colleague and found out that the TFSI anion, which earlier was stated as being a non-option, is alright for his work with Raman Spectroscopy. This does remove a lot of my worry from earlier this week and last about solubility for there are many articles in the literature that use 1:5 molar ratios of LiTFSI:CnPyrrTFSI, giving us plenty of room to play with. On the other hand, we have had concerns over whether our LiTFSI is actually dry, so today we will hopefully put our LiTFSI in a vacuum oven to sit overnight.
The Great Disaster of 2nd week (Thurs. July 30th 2016)-
We analyzed our 0.1M KCl solution today (6/30/16) and found that the solution contained rust-like particles and oil. This would indicate that at least the thermal fluid was leaking into the liquid cell (#2), and has serious implications for future testing. On further analysis slight corrosion of the electrodes were noted and although the damage is not significant there is serious concern on whether it can make accurate measurements anymore. We also noticed that the larger o-rings, around the electrodes, were significantly damaged and upon touch left black reside. We replaced the o-rings for this liquid cell and are attempting to run another 0.1Molal KCl solution to compare with the CRC standard. In order to ensure higher accuracy for this run I have decided to make a 100g solution of 0.1Molal KCl instead of the usual 10g sample. Given that our balances are only accurate to 4 decimal places, and I have my serious doubts about whether the last two digits are accurate, I want to ensure that we have the maximum accuracy for our solution, especially in deciding whether the liquid cell is still operational. At $20,000 a pop, I do not want to be in a position of 2nd guessing myself.
Drought in the Chemistry Building-
The DI water has been out for over a week and half now, and we are running out of stored DI water in order to clean our glassware. Given this, if it does not come back on soon we might have to halt our laboratory work. I was given quite a scare when our stockroom manager told me that the nano-pure water was out, the same system I had been getting water from for all my laboratory needs this entire week, and I immediately went downstairs and disassembled the liquid cell which had a 0.1M solution of KCl running composed of said nanopure water. Much to my relief I was later informed that the nanopure water was probably still ion free given the added filtration, and that using it while the DI water was out was just harder on the filters. Given this, I will probably have to run in Saturday and Sunday to run another, this time less panicked, 0.1M KCl test for liquid cell 2.
Find O-rings for a 26-year-old liquid cell (Fri. 7/1/16)-
I was asked to order (or at least find where to order from) new o-rings for the liquid cell. We have a 16452A Agilent Liquid Test Fixture. It seems that some of the o-rings ordered over the years are actually from Agilent or their new subsidiary company Keysight (now in charge of 16452A product), but some, especially the more specialized different rubber compounds, are ordered from Seal Company Enterprises in Tulsa, Oklahoma. I have decided to avoid buying from the Seal Company since these o-rings were probably special ordered and may be more expensive in general. I have located what I think is the right o-ring on the Keysight website, but want to confirm whether they come in pairs, what rubber they are made out of (I think they should be EPDM), and their dimensions. They run about $10 for an individual ring (I think). I have yet to hear back.