# Foam Stability Mediated by Cellulose Nanocrystal–Anionic Surfactant Interactions

## TL;DR

This study explores how cellulose nanocrystals and anionic surfactants interact to improve foam stability in sustainable aqueous systems.

## Contribution

The paper reveals how CNC–surfactant interactions can be tuned to control foam stability and interfacial properties for green applications.

## Key findings

- CNC slightly increased surfactant critical micelle concentration and reduced surfactant adsorption at the interface.
- CNC enhanced foam stability at low surfactant concentrations by forming percolated networks and reinforcing interfacial films.
- High surfactant concentrations dispersed CNC well, reducing viscoelasticity and foam stability.

## Abstract

The combination of cellulose nanocrystals (CNC) and anionic
alkyl
poly­(ether) carboxylate surfactants offers a sustainable approach
to modulating the interfacial and foaming properties of aqueous systems.
This study investigated CNC–surfactant interactions in bulk
and at the air–water interface using surface tension, interfacial
rheology, foaming tests, particle size, zeta potential, and electron
microscopy. CNC slightly increased the critical micelle concentration
and reduced surfactant adsorption at the interface, indicating an
interaction between the two components. Increasing the surfactant
concentration improved CNC dispersion, forming smaller, more uniform
aggregates. Although CNC addition slightly reduced foamability due
to slower surfactant diffusion and increased surface tension, it significantly
enhanced foam stability at low surfactant concentrations. This improvement
was attributed to aggregated CNC forming percolated networks and reinforcing
interfacial films. Dynamic surface tension and dilatational rheology
confirmed an increased interfacial viscoelasticity, evidencing stronger
interfacial layers. At high surfactant concentration, CNC was well
dispersed, resulting in lower viscoelasticity and reduced foam stability,
highlighting the importance of the CNC aggregation state. Overall,
CNC–surfactant interactions enable tunable control over interfacial
structure and foam stability, offering valuable insights for greener
formulations in personal care, food, and household applications.