# Ultrasound-Regulated Molecular Reorganization and Property Enhancement in Gelatin–Glycerol Films

## TL;DR

This study shows that low-power ultrasound can improve the structure and performance of gelatin-glycerol films, making them suitable for sustainable packaging and biomedical uses.

## Contribution

Introduces low-power direct-probe ultrasonication as a green method to enhance gelatin-glycerol films without additives.

## Key findings

- Low-power ultrasound promotes helix-like molecular packing and smooth film surfaces.
- Treated films show improved hydrophilicity, reduced defects, and better thermal stability.
- High-power ultrasound leads to porous structures and reduced performance.

## Abstract

The replacement of petroleum-based plastics with sustainable and biodegradable materials remains a critical challenge for food packaging and biomedical applications. Gelatin is an attractive natural biopolymer for film fabrication; however, its inherent brittleness, moisture sensitivity, and limited structural stability restrict practical use. In this work, for the first time, low-power direct-probe ultrasonication is introduced as a green and additive-free strategy to regulate molecular organization and enhance the performance of gelatin–glycerol composite films. Systematic variation in ultrasonic power and treatment duration revealed a strong dependence of film structure and properties on processing conditions. Low-power ultrasonication (20 W) promoted gelatin–glycerol interactions, induced a transition from loosely organized molecular arrangements to helix-like molecular packing at the nanometer scale, and produced smooth, compact microscale surface morphologies. As a result, these films exhibited enhanced hydrophilicity, reduced surface defects, and improved thermal stability. In contrast, high-power ultrasonication generated excessive cavitation, leading to large-scale porous structures and diminished thermal and surface performance. Therefore, this work identifies a distinct low-power ultrasonic window that enables controlled molecular reorganization and hierarchical structure formation in gelatin–glycerol systems. Structural and physicochemical analyses using SEM, FTIR, XRD, water contact angle measurements, and thermogravimetric analysis collectively elucidate the ultrasound-driven structure–property relationships within the gelatin–glycerol matrix. Overall, this study demonstrates that controlled ultrasonication enables precise tuning of gelatin-based film architecture and properties, offering a scalable and environmentally friendly route to high-performance biodegradable materials for sustainable packaging and biomedical applications.