Entropic Tightening

  Even without interactions, knots could be `tight:'

  Slip-links as surrogate (prime) knots:

   

    Entropy of a constrained slip-link (phantom chain in three dimensions):

  The most probable configurations are composed of a tight and an open loop!


  Self-avoiding Slip-links:

  A large body of work on polymer networks can be used to study slip-linked polymers.

  The number of configurations of a self-avoiding slip-link has the scaling form

  In the limit of a small (tight) loop, the above expression reduces to