%0 Book Section %1 statphys23_0359 %A Parsons, D.F. %A Williams, D.R.M. %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K chain collapsed copolymer globule montecarlo multiblock polymer single statphys23 topic-7 wang-landau %T Geometric frustration in the collapsed globule phases of single chain multiblock copolymers. %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=359 %X A Wang-Landau Monte-Carlo study of single chained AB-multiblock copolymers was performed. The multiblock copolymer was formed by repeating a symmetric AB diblock unit along the length of the whole polymer. Simulations were performed changing the length of the base AB unit for each calculation. The behaviour of the multiblock copolymers in collapsed globule phase divides into three categories depending on the length of the unit diblock: (1) Long block length. In the globule phase the polymer collapses down to a dumbell-shaped diglobule, with the A and B blocks separating into two separate spherical globules attached on one side (similar to the simple diblock copolymer). (2) Intermediate block length. A single spheroid globule is formed with A and B blocks separating to form a `tennis-ball' or `hand-shake' diglobule. When repulsion between A and B monomers is relaxed, the A and B blocks each form a spiral structure entwined around one another. (3) Short block length. A striped globule is formed, composed of alternating flat layers of A and B blocks. We attribute this behaviour to geometric frustration. The dumbell diglobule at long block length is formed by the competing forces of repulsion away from the solvent and repulsion of A and B monomers away from one another, resulting in a separate A and B globule. At intermediate block lengths the length of the block is too short to be able to fill a separate A or B globule, hence these globules become warped, trying to minimise the AB interface, resulting in the observed `handshake' diglobule. At shortest block lengths the small size of the block length relative to the total length of the collapsed globule means that the system behaves in a fashion similar to a bulk diblock copolymer, with the blocks separating into alternate layers. An analytical model is developed to explain the transition between the simple long block dumbell diglobule and the intermediate-length `handshake' diglobule. The block length at which the transition occurs scales with $N^1/6$, where $N$ is the total number of monomers. The Wang-Landau Monte-Carlo technique reveals a set of phase transitions occurring within the collapsed globule at different temperatures. In the case of the long and intermediate-length blocks, the globule passes through a series of collapsed globule states composed of four or five A or B globules just below the coil-globule transition temperature, followed by a triglobule state at slightly lower temperature, before reaching the diglobule states described above at the lowest temperatures accessible to the simulations. In the case of short block length, the higher temperature globule formed just below the coil-globule transition is a disordered globule with the A and B components fully dispersed among one another. The striped globule described above is formed below an order-disorder transition temperature.

@incollection{statphys23_0359, abstract = {A Wang-Landau Monte-Carlo study of single chained AB-multiblock copolymers was performed. The multiblock copolymer was formed by repeating a symmetric AB diblock unit along the length of the whole polymer. Simulations were performed changing the length of the base AB unit for each calculation. The behaviour of the multiblock copolymers in collapsed globule phase divides into three categories depending on the length of the unit diblock: (1) Long block length. In the globule phase the polymer collapses down to a dumbell-shaped diglobule, with the A and B blocks separating into two separate spherical globules attached on one side (similar to the simple diblock copolymer). (2) Intermediate block length. A single spheroid globule is formed with A and B blocks separating to form a `tennis-ball' or `hand-shake' diglobule. When repulsion between A and B monomers is relaxed, the A and B blocks each form a spiral structure entwined around one another. (3) Short block length. A striped globule is formed, composed of alternating flat layers of A and B blocks. We attribute this behaviour to geometric frustration. The dumbell diglobule at long block length is formed by the competing forces of repulsion away from the solvent and repulsion of A and B monomers away from one another, resulting in a separate A and B globule. At intermediate block lengths the length of the block is too short to be able to fill a separate A or B globule, hence these globules become warped, trying to minimise the AB interface, resulting in the observed `handshake' diglobule. At shortest block lengths the small size of the block length relative to the total length of the collapsed globule means that the system behaves in a fashion similar to a bulk diblock copolymer, with the blocks separating into alternate layers. An analytical model is developed to explain the transition between the simple long block dumbell diglobule and the intermediate-length `handshake' diglobule. The block length at which the transition occurs scales with $N^{1/6}$, where $N$ is the total number of monomers. The Wang-Landau Monte-Carlo technique reveals a set of phase transitions occurring within the collapsed globule at different temperatures. In the case of the long and intermediate-length blocks, the globule passes through a series of collapsed globule states composed of four or five A or B globules just below the coil-globule transition temperature, followed by a triglobule state at slightly lower temperature, before reaching the diglobule states described above at the lowest temperatures accessible to the simulations. In the case of short block length, the higher temperature globule formed just below the coil-globule transition is a disordered globule with the A and B components fully dispersed among one another. The striped globule described above is formed below an order-disorder transition temperature.}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Parsons, D.F. and Williams, D.R.M.}, biburl = {https://www.bibsonomy.org/bibtex/2a868486189a818891597718b754f1117/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {0adabf3729a44a771e602e7b8e74f3b3}, intrahash = {a868486189a818891597718b754f1117}, keywords = {chain collapsed copolymer globule montecarlo multiblock polymer single statphys23 topic-7 wang-landau}, month = {9-13 July}, timestamp = {2007-06-20T10:16:18.000+0200}, title = {Geometric frustration in the collapsed globule phases of single chain multiblock copolymers.}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=359}, year = 2007 }