Expanding Monomers as Anti-Shrinkage Additives

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Polymerization commonly causes volumetric shrinkage due to covalent bond formation.
• This shrinkage negatively impacts material properties.

Purpose of the Study:

• To review expanding monomers and their structure-property relationships.
• To highlight methods for quantifying volumetric changes during polymerization.

Main Methods:

• Literature review of expanding monomer classes.
• Analysis of structure-property correlations.
• Discussion of measurement techniques for volumetric changes.

Main Results:

• Expanding monomers, featuring cyclic structures, undergo ring-opening polymerization.
• This process transforms dense cyclic structures into less dense linear ones, causing volumetric expansion.
• Key monomer classes include cycloalkanes, oxacycles, benzoxazines, and thiocyclic compounds.

Conclusions:

• Expanding monomers offer a viable strategy to mitigate polymerization-induced volumetric shrinkage.
• Understanding the structure-property relationships of these monomers is crucial for material design.
• Spiroorthoesters, spiroorthocarbonates, cyclic carbonates, and benzoxazines are particularly promising expanding monomers.