Related Experiment Video
Updated: Jan 16, 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
Cyclic Macromolecular Chains Visualized by Cryo-EM and AFM Reveal a Ring Expansion Polymerization Mechanism in a
Raman Hlushko1, Vivek M Prabhu2, Alexander K Andrianov1
1Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States of America.
None:
We observed individual macromolecular chains with distinct ring topology when studying cryogenic electron microscopy (Cryo-EM) images of a high molar mass polyorganophosphazene in its vitrified aqueous solution. The presence of monocyclic chains was confirmed by visualizing samples of the same macromolecule in its absorbed form by using atomic force microscopy (AFM). The polymer, poly[di(carboxylatophenoxy)phosphazene], PCPP, is synthesized via a two-stage process, which includes a ring-opening polymerization (ROP) and a subsequent macromolecular substitution transformation. The visualization of macrocycles, which are 20-60 nm in diameter, provides direct proof of a ring extension polymerization (REP) mechanism occurring in the chain-growth process commonly employed for the synthesis of high molar mass polyphosphazenes. Asymmetric flow field flow fractionation (AF4) analysis shows the presence of a faster moving fraction, which can be potentially attributed to macrocycles.
More Related Videos
11:42Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers
Published on: June 20, 2019
09:22Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Related Concept Videos
Cationic Chain-Growth Polymerization: Mechanism
ATP and Macromolecule Synthesis
Most macromolecules are composed of single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
Conversion of...
Anionic Chain-Growth Polymerization: Mechanism
Radical Chain-Growth Polymerization: Chain Branching
Polymers
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)