What is the Order of Coil-Globule Transition

Polymer chains with peculiar interactions, in which third (or higher) virial coefficient becomes negative at a temperature (or solvent conditions) where second virial coefficient is still positive. An example is the system in which monomers can form complexes, similar to micells, with a defined number of participants. Following de Gennes, this is sometimes called p-cluster model. 

Macromolecules capable of internal local orientational ordering, usually of nematic type, in the globular state, like in toroid DNA case. Macromolecules with other types of symmetry or organization in the globule, up to a crystal. 

Polymers in which monomers can have two different states, such as helical or non-helical, when globule can be formed due to the jump in, e.g., the degree of helicity. 

Polymers in which monomers can absorb ligands from the solvent, such that globule can be formed due to a jump in the number of absorbed ligands. 

Polymer chains in multicomponent solvents, when globule formation can be achieved by the re-distribution of solvent components between the globule interior and the outer solution. 

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