Related Experiment Video
Updated: Oct 18, 2025
06:55
Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level
Published on: September 26, 2016
8.1K
Effects of chain length on Rouse modes and non-Gaussianity in linear and ring polymer melts
Shota Goto1, Kang Kim1, Nobuyuki Matubayasi1
1Division of Chemical Engineering, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
The Journal of Chemical Physics
|October 2, 2021
Summary
Ring polymer melts exhibit Rouse-like dynamics, unlike linear polymers which show reptation. Ring polymers also display suppressed non-Gaussianity, indicating distinct dynamic behavior in melts.
Area of Science:
- Polymer Physics
- Computational Materials Science
Background:
- Understanding polymer dynamics is crucial for material properties.
- Ring polymers exhibit unique topological constraints compared to linear polymers.
Purpose of the Study:
- To investigate the dynamic behavior of ring polymer melts.
- To compare ring polymer dynamics with linear polymers using simulations.
- To analyze non-Gaussian parameters for insights into molecular motion.
Main Methods:
- Molecular dynamics simulations using the Kremer-Grest bead-spring model.
- Rouse mode analysis to quantify relaxation dynamics.
- Analysis of non-Gaussian parameters for monomer and center-of-mass displacements.
Main Results:
- Ring polymers demonstrate Rouse-like relaxation dynamics, dependent on chain length.
- Linear polymers exhibit a crossover from Rouse to reptation behavior.
- Non-Gaussianity is suppressed in ring polymers, particularly for center-of-mass motion at long chain lengths.
Conclusions:
- Ring polymers possess distinct dynamic characteristics compared to linear polymers.
- Topological differences significantly influence polymer melt dynamics.
- The suppressed non-Gaussianity in ring polymers suggests altered diffusion mechanisms.
Related Concept Videos
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
2.8K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
2.8K
01:09Radical Chain-Growth Polymerization: Mechanism
2.9K
The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this...
2.9K
01:04Anionic Chain-Growth Polymerization: Mechanism
2.1K
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael...
2.1K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.1K
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
2.1K
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
3.5K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
3.5K
01:10Radical Chain-Growth Polymerization: Overview
2.8K
Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...
2.8K