9 comments on “My Research Part 2: Liquid Crystals

  1. This might be quite technical but your explanation seems to work for actual balls but 2 sec google search seem to indicate that they only work when it is a polymer, is this right ? If so Why ?

    • It isn’t just polymers that work, any molecule with the right shape and size would work. However, polymers are nice because most of them, in solution, will coil on themselves and form ball shapes. Also, it is easy to make polymers be shorter or longer chains. This corresponds to a bigger or smaller ball in the solution causing a different depletion interaction. So, in short, polymers are nice because chemists have figured out how to very precisely control their attributes.

  2. Hmm I read about the mathematical model of this and the polymers are modelled as hard spheres. Is there exptl observation when it is actually spherical objects ?
    How small is small : what is relation between the ball size and cylinder length for this to work ?

    • I honestly am not sure on either count. I am in the process of learning this stuff. I do know that the rods (viruses) must have a ratio of their length to diameter of >~10 in order for the depletion interaction to work correctly. Also, they must be either rigid or semi-flexible. In physics language, that means their persistence length must be much longer than the length of the rod. Both of these conditions are easily satisfied by these viruses. I unfortunately know less about the depletant material itself.

  3. Pingback: My Research Part 3: Optical Tweezers « The Philosophical Physicist

  4. Pingback: My Research Part 4: Stretching Flagella « The Philosophical Physicist

  5. Pingback: My Research Part 5: Flagella Bundles « The Philosophical Physicist

  6. Pingback: My Research Part 6: Applications « The Philosophical Physicist

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