# Hexadecylamine Addition Promotes Crystallization-Driven Functionalities in Freezing–Thaw PVA Hydrogels

## TL;DR

Adding hexadecylamine to PVA hydrogels during freezing-thawing improves their structure and properties, enabling self-healing and better adhesion without extra chemicals.

## Contribution

A novel method for creating functional PVA hydrogels using hexadecylamine to drive crystallization without surfactants or cross-linkers.

## Key findings

- Hexadecylamine promotes PVA crystallization and phase separation during freezing–thaw blending.
- PVA/C16 hydrogels show enhanced thermomechanical properties and self-healing capabilities.
- The method enables gel formation in water without surfactants, solvents, or cross-linkers.

## Abstract

Poly­(vinyl alcohol) (PVA) is widely employed for hydrogel
fabrication
due to its ability to form stable, physically or chemically cross-linked
three-dimensional networks. Among production methods, the freezing–thaw
(F–T) technique stands out for its simplicity and effectiveness.
This study presents a straightforward methodology for preparing functional
PVA hydrogels in aqueous media by blending PVA with a crystallizable
hexadecyl alkylamine (C16). Incorporating small amounts of hydrophobic,
amphiphilic hexadecylamine into PVA hydrogels via freezing–thaw
blending significantly alters crystallization and network structure,
enabling gel formation in water without surfactants, solvents, or
cross-linkers. C16 enhances phase separation and promotes PVA crystalline
domains while remaining amorphous. The resulting PVA/C16 hydrogels
exhibit enhanced thermomechanical properties, demonstrating additional
functionalities such as self-healing and improved adhesion to polar
surfaces. This crystallization-driven gelation via immiscible blending
offers a scalable strategy with potential in wearable electronics,
soft robotics, and biomedical devices.