A recent article in the Journal of Polymer Science explores the development of chitosan–silanized hexagonal boron nitride (hBN) nanocomposite films, focusing on their structural, mechanical, and barrier properties.
The research is motivated by the growing demand for sustainable materials in fields such as packaging and biomedical applications. The study demonstrates how surface-modified nanofillers can enhance the performance of biodegradable polymer films, helping to overcome key limitations of chitosan.
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Background
Chitosan is a biopolymer derived from chitin. It is known for its biodegradability, nontoxicity, and excellent film-forming properties, which make it an attractive material for eco-friendly applications. However, chitosan films typically suffer from weak barrier properties and limited mechanical strength, restricting their practical use.
To address these limitations, researchers have explored reinforcing chitosan with nanofillers. Among them, hexagonal boron nitride (hBN) is known for its high thermal conductivity, chemical stability, and UV-blocking ability. Previous studies have shown that adding hBN to chitosan improves barrier performance and thermal stability. However, most have used untreated hBN, which limits dispersion and interfacial bonding within the polymer.
This study introduces a surface modification technique—silanization of hBN using vinyl trimethoxy silane (VTS)—to enhance its compatibility with chitosan. The goal is to improve dispersion, strengthen hydrogen bonding, and ultimately boost the mechanical and barrier properties of the resulting nanocomposite films.
The Current Study
The researchers used a solution casting method to prepare the chitosan–hBN nanocomposite films. Chitosan was extracted from shrimp shells and dissolved into a concentrated solution. The surface of hBN was modified using VTS to improve compatibility with the polymer matrix.
The success of the silanization and the dispersion of hBN within the chitosan matrix were confirmed through Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). SEM images showed that the hBN was effectively incorporated and evenly distributed throughout the films.
Mechanical testing was carried out following ISO 527-2 standards using an Instron 5944 machine to evaluate tensile strength. Chemical resistance was assessed by immersing film samples in a dilute NaOH solution for ten weeks.
To evaluate barrier performance, the team measured water vapor and oxygen permeability, key indicators for potential use in packaging applications. Additionally, cytotoxicity tests were conducted using L929 fibroblast cells. The films were incubated in cell culture media, and cell viability was measured over time to determine biocompatibility.
Results and Discussion
The incorporation of silanized hBN led to notable improvements in film performance. The swelling ratio improved by 18.6% compared to pure chitosan, suggesting enhanced structural integrity and water resistance.
Barrier tests showed a significant reduction in water vapor permeability—from 2.54 × 10−10 g−1 s−1 Pa−1 for pure chitosan to 1.47 × 10−10 g−1 s−1 Pa−1 for the 0.9 % hBN composite. Oxygen permeability also dropped substantially, from 1350.79 cm³/m² to 542.2 cm³/m² day, confirming the material’s potential for moisture- and oxygen-sensitive applications.
Thermal analysis showed higher degradation temperatures in the nanocomposites, indicating improved thermal stability. The sample with 0.9 % hBN achieved the best mechanical results, with a tensile strength of 77.9 MPa and a Young’s modulus of 6299.86 MPa, demonstrating the reinforcing effect of hBN at relatively low loadings.
The films also provided strong UV protection, with UV-A and UV-B blocking efficiencies of 98.51 % and 96.40 %, respectively.
Cytotoxicity testing confirmed the films’ safety. Cell viability remained high at all time points and across all hBN concentrations, supporting their use in biomedical and food-contact applications.
Conclusion
This study successfully demonstrates the development of chitosan–silanized hBN nanocomposite films with enhanced mechanical strength, thermal stability, and barrier properties. The surface modification of hBN using VTS proved crucial for improving dispersion and interfacial bonding in the polymer matrix.
The resulting materials show strong potential for eco-friendly packaging, particularly in food and biomedical applications where barrier performance, biodegradability, and biocompatibility are essential. The research highlights the value of combining natural polymers with surface-engineered nanofillers to meet modern performance and sustainability standards.
Future work could focus on evaluating the films under real-world storage conditions and assessing their long-term environmental impact. The findings encourage broader exploration of silanized nanomaterials in biopolymer systems for scalable, sustainable solutions.
Journal Reference
Yılmaz Z., et al. (2025). Chitosan-silanized hexagonal boron nitride nanocomposite films and properties. Journal of Applied Polymer Science, 0, e57128. DOI: 10.1002/app.57128 https://onlinelibrary.wiley.com/doi/10.1002/app.57128