Related Experiment Video
Updated: Sep 29, 2026

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
Dynamic crossover to tricriticality and anomalous slowdown of critical fluctuations by entanglements in polymer
A F Kostko1, M A Anisimov, J V Sengers
1Institute for Physical Science and Technology and Department of Chemical Engineering, University of Maryland, College Park, Maryland 20742, USA.
Abstract:
We have performed accurate dynamic light-scattering measurements near critical demixing points of solutions of polystyrene in cyclohexane with polymer molecular weight ranging from 200 000 to 11.4 x 10(6). Two dynamic modes have been observed, "slow" and "fast," which result from a coupling between diffusive relaxation of critical fluctuations of the concentration and viscoelastic relaxation associated with the entanglement network of the polymer chains. The coupling with the viscoelastic mode causes an additional slowdown of the critical mode on top of the uncoupled diffusion mode. By implementing crossover from the critical to the theta-point tricritical behavior for both static and dynamic properties, we are able to present a quantitative description of the phenomenon and obtain a scaling of the viscoelastic parameters as a function of the molecular weight.
Related Concept Videos
Radical Chain-Growth Polymerization: Mechanism
Radical Chain-Growth Polymerization: Overview
Radical Chain-Growth Polymerization: Chain Branching
Cationic Chain-Growth Polymerization: Mechanism
Ziegler–Natta Chain-Growth Polymerization: Overview
Polymer Classification: Crystallinity
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...

