Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Polymers: Molecular Weight Distribution

Polymers: Molecular Weight Distribution

For any given polymer, the weight average molecular weight (Mw) is higher than, if not equal to, the number average molecular weight (Mn). The only situation in which the weight average molecular weight and the number average molecular weight are equal is when a polymer consists only of chains with equal molecular weight. However, this never happens in a synthetic polymer, since it is difficult to control the polymerization process up to a molecular level with accuracy to a hundred percent.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

An acoustic platform for facile, size-targeted polymeric nanoparticle synthesis.

Chemical science·2026

Same author

Responsible chemistry for a changing world: IUPAC's guiding principles.

Chemical science·2026

Same author

High-Throughput Kinetic Screening of UV and Visible Light-Induced Copper-RDRP in Continuous Flow Using Inline Benchtop NMR Analysis.

JACS Au·2026

Same author

A robotic approach to polymerisation kinetics: a case study on copolymerisation parameter estimation.

Chemical science·2026

Same author

Scalable Miniemulsion Polymerization of Methyl Methacrylate (MMA) in Continuous Flow.

JACS Au·2026

Same author

Multidimensional kinetic study on the organocatalyzed ring-opening polymerization (ROP) of l-lactide <i>via</i> a robotic high-throughput flow platform.

Chemical science·2026

Same journal

Reprocessable Disulfide-Based Vitrimers with Adhesive Properties.

Macromolecular rapid communications·2026

Same journal

Micro- and Nanopatterning of Highly Conductive PEDOT Thin Films.

Macromolecular rapid communications·2026

Same journal

From Molecular Structure to Macroscopic Performance: Insights into Polycarbosilane Curing.

Macromolecular rapid communications·2026

Same journal

High-Yield Synthesis of Molecular Bottlebrushes With Block Copolymer Side Chains by the Copper Superoxido Complex Enabled ATRP via a Grafting-From Approach.

Macromolecular rapid communications·2026

Same journal

Chemically and Mechanically Recyclable Polyolefins Incorporating Covalent Adaptable Networks.

Macromolecular rapid communications·2026

Same journal

Designing Thermally Stable DNA Hydrogels via Entropically-Driven Acridine Intercalation.

Macromolecular rapid communications·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Sep 17, 2025

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

Published on: September 26, 2016

Polymer Dispersity Determination by Diffusion-Ordered Spectroscopy (DOSY).

Igor W F Silva¹, Alasdair McKay², Tanja Junkers¹

¹School of Chemistry, Polymer Reaction Design group, Monash University, Clayton, VIC, Australia.

Macromolecular Rapid Communications

|July 3, 2025

Summary

This summary is machine-generated.

Diffusion-ordered NMR spectroscopy (DOSY) can accurately determine polymer dispersity (Ð) and molar mass, even for broader distributions. Standard deviation (σ) shows better correlation than dispersity for polymer characterization.

Keywords:

Dispersity Molecular weight PDI PFG‐NMR Standard deviation

More Related Videos

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Published on: January 9, 2017

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

Published on: June 10, 2018

Related Experiment Videos

Last Updated: Sep 17, 2025

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

Synthesis of Cyclic Polymers and Characterization of Their Diffusive Motion in the Melt State at the Single Molecule Level

Published on: September 26, 2016

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Measurement of Particle Size Distribution in Turbid Solutions by Dynamic Light Scattering Microscopy

Published on: January 9, 2017

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

Characterization of Synthetic Polymers via Matrix Assisted Laser Desorption Ionization Time of Flight MALDI-TOF Mass Spectrometry

Published on: June 10, 2018

Area of Science:

Polymer Chemistry
Analytical Chemistry
Spectroscopy

Background:

Dispersity (Ð) is a key polymer characteristic.
Size exclusion chromatography (SEC) is the standard for dispersity determination.
Diffusion-ordered NMR spectroscopy (DOSY) shows promise for molar mass determination but struggles with dispersity.

Purpose of the Study:

To evaluate DOSY for reliable dispersity measurement in polymers.
To correlate SEC and DOSY measurements for various polystyrenes.
To assess the accuracy of DOSY in determining molar mass distribution (MMD).

Main Methods:

Synthesis of 26 polystyrenes with varying dispersity (1.1–3.7) and molar mass (3.0–22.4 kg∙mol⁻¹).
Comparison of molar mass distribution (MMD) data from SEC and DOSY.
Application of inverse Laplace transformation (ILT) for DOSY analysis.

Main Results:

DOSY-ILT accurately determines number and weight-average molar mass, enabling dispersity calculation.
Inverse Laplace transformation (ILT) struggles to represent MMD shape for non-narrowly dispersed polymers.
SEC and DOSY-ILT show good correlation up to Ð = 2.0.
Standard deviation (σ) and coefficient of variation correlate better with SEC across the studied range.

Conclusions:

DOSY is a viable technique for accurate polymer dispersity and molar mass determination.
Standard deviation (σ) offers improved correlation for polymer characterization compared to dispersity.
DOSY expands polymer analysis capabilities beyond traditional SEC methods.