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Step-Growth Polymerization: Overview

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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.
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Molecular Weight of Step-Growth Polymers

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Polymers: Molecular Weight Distribution

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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.

Polymer Classification: Stereospecificity

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Polymers: Defining Molecular Weight

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Scaling Concepts in Serpin Polymer Physics.

Samuele Raccosta¹, Fabio Librizzi¹, Alistair M Jagger^2,3

¹Institute of Biophysics, National Research Council of Italy, via Ugo La Malfa 153, 90146 Palermo, Italy.

Materials (Basel, Switzerland)

|June 2, 2021

Summary

This summary is machine-generated.

Alpha-1 antitrypsin polymers, implicated in serpinopathies, form flexible chains. This study reveals a power law relationship between polymer size and mass, characterizing them as random linear chains.

Keywords:

atomic force microscopy conformational disease dynamic light scattering polymer theory serpin polymers serpins

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Area of Science:

Biophysics
Polymer Physics
Molecular Biology

Background:

Alpha-1 antitrypsin is a serpin family protease inhibitor.
Serpin polymerization causes genetic conformational diseases known as serpinopathies.
Polymers appear as flexible, heterogeneous, beads-on-a-string structures.

Purpose of the Study:

To characterize the size and shape of alpha-1 antitrypsin polymers.
To investigate wild-type (M) and the pathological Z variant (Glu342→Lys).
To apply polymer physics scaling concepts to understand polymer structure.

Main Methods:

Atomic force microscopy (AFM) for polymer imaging.
Time-lapse dynamic light scattering (DLS) for size in solution.
Analysis of polymers on mica and in solution.

Main Results:

Demonstrated a power law relationship between polymer size (end-to-end distance, hydrodynamic radius) and mass.
Mass is proportional to contour length.
Alpha-1 antitrypsin polymers exhibit characteristics of random linear chains.

Conclusions:

Alpha-1 antitrypsin polymers are flexible, random linear chains with low persistence length.
Findings provide insights into the physical basis of serpinopathies.
Characterization aids understanding of disease mechanisms in alpha-1 antitrypsin deficiency.