Related Experiment Video
Updated: Jun 25, 2026
08:00
DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers
Published on: October 25, 2017
Rippling of polymer nanofibers
Xiang-Fa Wu1, Yulia Y Kostogorova-Beller, Alexander V Goponenko
1Department of Engineering Mechanics, Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0526, USA. Xiangfa.Wu@ndsu.edu
Summary
Surface rippling in polymer nanofibers is caused by axial stretching, surface tension, and nonlinear elasticity. A new model predicts critical conditions for this instability in compliant nanofibers.
Area of Science:
- Polymer Science
- Materials Science
- Continuum Mechanics
Background:
- Surface rippling observed in electrospun polyacrylonitrile and polyimide nanofibers under tension.
- Understanding nanofiber instability is crucial for nanoscale material applications.
Purpose of the Study:
- To develop a model for surface rippling evolution in polymer nanofibers under axial stretching.
- To investigate the influence of surface tension and nonlinear elasticity on nanofiber instability.
Main Methods:
- A one-dimensional nonlinear elastic model for incompressible, hyperelastic Mooney-Rivlin solids.
- Linear perturbation analysis of the nanofiber's static equilibrium state under finite axial prestretching.
Main Results:
- Derived governing equations for surface rippling initiation and evolution.
- Determined critical stretch and ripple wavelength based on material properties and fiber radius.
- Identified a critical fiber radius below which nanofibers are intrinsically unstable.
Conclusions:
- The model accurately predicts rippling conditions in compliant polymer nanofibers.
- Provides a continuum mechanics framework for studying nanoscale surface instability and wave propagation.
Related Concept Videos
01:03Step-Growth Polymerization: Overview
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...
01:20Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
01:08Molecular Weight of Step-Growth Polymers
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
01:04Anionic Chain-Growth Polymerization: Mechanism
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 acceptor.
01:17Radical Chain-Growth Polymerization: Chain Branching
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...
01:10Radical Chain-Growth Polymerization: Overview
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...