Week 4 in the CNT Lab

This week I’ve gotten to see and do a lot of new things. Since we finally had some purified carbon nanotubes (CNTs), we put them inĀ  chlorsulfonic acid to dissolve the CNTs. The result is a viscous black liquid that we can then analyze.

We then used some of the dissolved nanotubes to make a sample in capillary tubes to be analyzed with Polarized Optical Microscopy (POM), To make the sample, you have to draw up some of the liquid into a tiny glass tube. Then you have to use a blowtorch to melt both ends of the tube. The POM was being finicky, so we didn’t actually get to observe the samples.

We then used an extensional rheometry technique that was developed in the Pasquali lab to determine the aspect ratio of our CNTs. There are two pistons in a glove box that are really close to each other. You take a drop of the dissolved CNTs and place it between the pistons. You record video of the CNTs pulling apart. Here’s what the Pasquali group paper says about the extensional rheometry: “The method is based on measuring the extensional viscosity of CNT solutions in chlorosulfonic acid with a customized capillary thinning rheometer and determining CNT aspect ratio from the theoretical relation between extensional viscosity and aspect ratio in semidilute solutions of rigid rods.” I’m still trying to figure out what that means…

 

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