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Determination of Molar Masses of Polymers I

Determination of Molar Masses of Polymers I

Polymerization produces macromolecules with a range of chain lengths due to the random nature of molecular growth processes. As chains form and terminate at different stages, a single polymer sample contains molecules of varying sizes rather than a uniform structure. This variability is described using average molar masses and distribution-related parameters, which together provide a comprehensive understanding of polymer characteristics.The distribution of molar masses plays a critical role in...

Step-Growth Polymerization: Overview

Step-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...

Molecular Weight of Step-Growth Polymers

Molecular 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...

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.

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Related Experiment Video

Updated: Jun 24, 2026

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

Developing dual-beam methodologies for the study of heterogeneous polymer-based systems.

J Benawra¹, A M Donald, M Shannon

¹BSS Group, Department of Physics, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, U.K.

Journal of Microscopy

|April 2, 2009

Summary

A new combined focused ion beam/environmental scanning electron microscope (FIB/ESEM) method allows detailed imaging of polymer internal structures. This technique minimizes sample damage, enabling clear visualization of complex polymer blends.

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

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Polymer Microarrays for High Throughput Discovery of Biomaterials

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Published on: January 25, 2012

Area of Science:

Materials Science
Polymer Science
Microscopy Techniques

Background:

Imaging internal structures of heterogeneous polymers is challenging.
Conventional methods like ultramicrotomy can cause sample damage.
Environmental scanning electron microscopy (ESEM) faces charging issues with insulating polymers.

Purpose of the Study:

To introduce a novel FIB/ESEM technique for imaging complex polymer heterostructures.
To overcome limitations of existing methods in polymer internal structure analysis.
To demonstrate controlled milling and imaging of polymer cross-sections.

Main Methods:

Utilized a combined focused ion beam (FIB) and environmental scanning electron microscope (ESEM).
Employed positively charged gallium ions for controlled milling of polymer samples.
Used a defocused low-energy primary electron beam to minimize ion beam damage.
Imaged cross-sections of phase-separated polystyrene-polybutadiene blends.

Main Results:

Successfully milled and imaged internal structures of polymer blends without significant damage.
ESEM imaging of exposed polymer structures was achieved without charging artifacts.
The observed morphology of polystyrene-polybutadiene blends matched previous ultramicrotomy and transmission electron microscopy results.

Conclusions:

The combined FIB/ESEM approach provides a powerful new tool for analyzing polymer internal structures.
This method offers controlled sample preparation and high-resolution imaging of heterogeneous polymeric materials.
The technique is suitable for studying insulating polymer systems, overcoming common imaging challenges.