The competition of hydrogen-like and isotropic interactions on polymer collapse

Abstract

We investigate a lattice model of polymers where the nearest-neighbour monomer-monomer interaction strengths differ according to whether the local configurations have so-called ``hydrogen-like'' formations or not. If the interaction strengths are all the same then the classical $\theta$-point collapse transition occurs on lowering the temperature, and the polymer enters the isotropic liquid-drop phase known as the collapsed globule. On the other hand, strongly favouring the hydrogen-like interactions give rise to an anisotropic folded (solid-like) phase on lowering the temperature. We use Monte Carlo simulations up to a length of 256 to map out the phase diagram in the plane of parameters and determine the order of the associated phase transitions. We discuss the connections to semi-flexible polymers and other polymer models. Importantly, we demonstrate that for a range of energy parameters two phase transitions occur on lowering the temperature, the second being a transition from the globule state to the crystal state. We argue from our data that this globule-to-crystal transition is continuous in two dimensions in accord with field-theory arguments concerning Hamiltonian walks, but is first order in three dimensions.

References in corpus (3)

• Continuous melting of compact polymers
• Scaling of a collapsed polymer globule in 2D
• Controlling Secondary Structures of Bio-Polymers with Hydrogen-Like Bonding

Cited by in corpus (4)

• Semi-flexible hydrogen-bonded and non-hydrogen bonded lattice polymers
• Exact Solution of Semi-Flexible and Super-Flexible Interacting Partially Directed Walks
• The statistical mechanics of the two-dimensional hydrogen-bonding self-avoiding walk including solvent effects
• Bethe approximation for the hydrogen-bonding self-avoiding walk in a solvent