Simulation of the Coiling of a Polymer Strand
Simulation of the Coiling of a polymer strand
Tsvetoslav Pavlov Department of Materials, Imperial College London, United Kingdom
27th Feb 2012
1. Abstract
This study will examine the temperature dependence of internal energy, heat capacity and R2 value (representative of the end to end distance) using a Langevin Dynamics simulation. It will also consider the dependence of the internal energy, heat capacity and R2 value with increasing polymer chain length. Internal energy has been found to be is negative at low temperatures, increases linearly with temperature and becomes positive at high temperatures. Heat capacity seems to increase linearly with a higher number of atoms in the chain due to additional atoms storing additional energy. The internal energy increases initially with a higher number of atoms. with increasing atomic separation. It then reaches a peak and decreases rapidly with further increases in chain length. This has been explained to be due to the negative eect of non- bonding interactions
2. Introduction
For many applications the interaction of a polymer with a solvent is vital. Polymer interactions can be examined using computational methods such as a Metropolis Monte Carlo method, Molecular Dynamics or Langevin Dynamics. It is important to know when for a certain system a solvent is good, bad or in-between (theta solvent). A good solvent would maximise the polymer-solvent interaction by unfolding while a bad solvent will minimize these interactions by keeping the polymer folded. It is also important to understand how the polymer behaves at dierent temperatures and chain lengths. Computer simulations allow for a polymer to be examined in great detail whereby very accurate values can be obtained, the accuracy of which depends on the accuracy of the applied model. Using computer simulations removes the costs associated with numerous lab experiments.
3. Method
Langevin Dynamics has been used to set up the simulation. It is
Tsvetoslav Pavlov Department of Materials, Imperial College London, United Kingdom
27th Feb 2012
1. Abstract
This study will examine the temperature dependence of internal energy, heat capacity and R2 value (representative of the end to end distance) using a Langevin Dynamics simulation. It will also consider the dependence of the internal energy, heat capacity and R2 value with increasing polymer chain length. Internal energy has been found to be is negative at low temperatures, increases linearly with temperature and becomes positive at high temperatures. Heat capacity seems to increase linearly with a higher number of atoms in the chain due to additional atoms storing additional energy. The internal energy increases initially with a higher number of atoms. with increasing atomic separation. It then reaches a peak and decreases rapidly with further increases in chain length. This has been explained to be due to the negative eect of non- bonding interactions
2. Introduction
For many applications the interaction of a polymer with a solvent is vital. Polymer interactions can be examined using computational methods such as a Metropolis Monte Carlo method, Molecular Dynamics or Langevin Dynamics. It is important to know when for a certain system a solvent is good, bad or in-between (theta solvent). A good solvent would maximise the polymer-solvent interaction by unfolding while a bad solvent will minimize these interactions by keeping the polymer folded. It is also important to understand how the polymer behaves at dierent temperatures and chain lengths. Computer simulations allow for a polymer to be examined in great detail whereby very accurate values can be obtained, the accuracy of which depends on the accuracy of the applied model. Using computer simulations removes the costs associated with numerous lab experiments.
3. Method
Langevin Dynamics has been used to set up the simulation. It is