Ring polymers as topological glass, a new phase of matter?
Lo, Wei-Chang (2012) Ring polymers as topological glass, a new phase of matter? PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b2568718~S1
In this thesis the dynamic properties of unknotted ring polymers at high densities
is investigated. We hypothesise an unusual type of glass transition which is purely
attributed to the topological constraints between the penetrating rings.
A mean-field model is developed to describe the strongly constrained ring
polymers as ideal lattice trees. Equilibrium properties can be derived within the
framework of statistical thermodynamics using an argument based on structural
recurrence. Here each ring can be seen as a linear object|as a loop strand with
The ring polymers were simplified as loop strands without any branching.
We focused on the constraints emerging from the circular topology, and the polymer
dynamics was simulated using a Monte Carlo technique. The degree of inter-ring
penetrations essentially controls the slowing of dynamics and represents a universal
parameter for the glass transition. The penetrating rings form a percolating network
involving reversible quasi-topological entanglements. As such, the stress relaxation
of each ring is prolonged by the coupled penetrations which have limited pathways
to release constraints from one another.
The simulation data suggest the existence of a glassy material exclusively
formed by the topological constraints associated with the circular structure. In
order to test the picture of topological glass, the
uorescence-labelled circular DNA
was used to observe its self-diffusion in the entangled state. The experimental
method has demonstrated its potential for the future investigation of the dynamics
of entangled ring polymers despite the fact that it failed to provide evidence of the
glassy state in our experiment.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||Q Science > QC Physics|
|Library of Congress Subject Headings (LCSH):||Polymers, Phase transformations (Statistical physics)|
|Official Date:||March 2012|
|Institution:||University of Warwick|
|Theses Department:||Department of Physics|
|Supervisor(s)/Advisor:||Turner, Matthew S.|
|Sponsors:||University of Warwick. Dept. of Physics|
|Extent:||vi, 90 leaves : ill., charts|
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