# Sustainable, Safe, and Effective (Super)Hydrophobic Coatings for Cellulosic Fiber Material via Alkyl Ketene Dimer and Polysaccharide Integration

## TL;DR

This paper introduces a new eco-friendly hydrophobic coating for cellulosic fibers using AKD and natural polysaccharides, offering a sustainable alternative to harmful chemicals.

## Contribution

The novel biodegradable hydrophobic coating combines AKD with natural polysaccharides, achieving superhydrophobic properties and durability.

## Key findings

- Coatings achieved water contact angles of 126° to 153°, showing strong hydrophobicity.
- Coatings resisted water absorption for up to 5 hours and survived 30 laundry cycles.
- SEM–EDX and FTIR confirmed uniform coverage and covalent bonding of AKD to cellulose.

## Abstract

In light of increasing environmental and regulatory restrictions
on per- and polyfluoroalkyl substances (PFAS), silicones, and other
persistent synthetic hydrophobic agents, we report the development
of novel biodegradable, water-based hydrophobic coatings for cellulosic
fiber materials based on alkyl ketene dimer (AKD) and naturally derived
polysaccharides alginate, cellulose nanofibers, starch, and agar as
matrices. Coatings on the cellulosic fiber material were applied through
screen printing and cured at low temperatures. The prepared coatings
transformed the initially (super)­hydrophilic cellulosic fibers into
a hydrophobic material, with static water contact angles ranging from
126° to 153°. Application of the coatings extended water
drop absorption times from immediate uptake to as long as up to 5
h, exhibiting rolling-off behavior consistent with lotus-leaf-like
hydrophobicity. SEM–EDX analysis revealed well-defined microstructuring
and uniform elemental distribution, confirming complete coverage of
the cellulosic fibers. FTIR spectroscopy and sequential organic solvent
extraction provided evidence of covalent AKD–cellulose bonding,
confirming successful chemical surface modification of the substrate.
The coatings demonstrated excellent durability, maintaining hydrophobic
performance even after 30 laundering cycles and exhibiting resistance
to chemical and mechanical stress. A synergistic effect between AKD
and polysaccharides was observed and explained: while AKD imparts
intrinsic hydrophobicity, the polysaccharides act as functional stabilizers
and physical barriers, improving coating uniformity, adhesion, and
long-term performance.