On June 12, 2025, Kairytė and Levina published an article in Applied Sciences entitled "The Impact of Dextrin-Activated Expanded Perlite and Vermiculite Particles on the Performance of Thermal Insulating Rapeseed Oil-Based Polyurethane Foam Composites". The publication presents a compelling case study on harnessing polysaccharide chemistry for advanced material functionalization. The research focuses on improving the performance of sustainable, rapeseed oil-derived polyurethane foams. The core innovation lies in using the bio-derived glycan, Dextrin, to chemically modify the surfaces of expanded perlite and vermiculite mineral fillers. The main finding is that this glycan-mediated activation significantly enhances the filler's compatibility and efficiency within the bio-polyol matrix, resulting in composite foams with superior thermal insulation properties.

Overview

The transition toward sustainable industrial chemistry necessitates replacing petroleum-based polymers with renewable alternatives. In the polyurethane industry, this involves substituting traditional polyols with bio-polyols, such as those derived from rapeseed oil. However, integrating mineral fillers—critical for achieving optimal mechanical and thermal performance—into these bio-based matrices often presents compatibility challenges due to the disparity between the hydrophobic polymer matrix and the hydrophilic mineral surfaces. Conventional surface modification agents are toxic or derived from non-renewable sources. This paper addresses this crucial gap by leveraging a common, non-toxic, and bio-derived Polysaccharide (dextrin) to bridge this chemical divide, ensuring the longevity and widespread adoption of sustainable PU foams in insulation applications.

Research Results

• Glycan-Silanol Interfacial Engineering

The first critical step involved the chemical activation of the mineral fillers—expanded perlite and vermiculite—using dextrin. Employing Fourier-transform infrared (FTIR) spectroscopy, the team confirmed the successful binding of the polysaccharide to the mineral surfaces. This analysis revealed a profound difference in the interfacial chemistry: while dextrin exhibited a partial reaction with the silanol groups on the perlite (PerDex) surface, the interaction with vermiculite (VermDex) appeared to yield a full reaction. This complete functionalization suggests the formation of a highly robust Dex–O–Si–O–Dex linkage, indicating a stable, covalent polysaccharide bridge between the inorganic filler and the future polymer matrix. This precise control over the glycan-silanol interface is a major contribution to materials glycochemistry.

Fig.1 Proposed Verm and Per particles activation with Dex. (Kairytė & Levina, 2025)

Fig.2 FTIR spectra of fillers: (a) Dex, Per, and PerDex (red circle indicates C-H stretching) and (b) Dex, Verm, and VermDex. (Kairytė & Levina, 2025)

• Bio-Polyol Composite Synthesis and Foam Morphology

Following filler activation, the modified PerDex and VermDex particles were successfully incorporated into the bio-polyol system, which uses a polyol derived from rapeseed oil. The introduction of these functionalized fillers into the polyurethane foaming reaction mixture led to distinct morphological outcomes. The dextrin layer acted as a compatibilizer, effectively mediating the dispersion of the hydrophilic mineral in the semi-hydrophobic bio-polyol, stabilizing the growing foam cells. Compared to unmodified fillers, the foams containing the glycan-activated VermDex showed optimal structural characteristics, exhibiting a more uniform cell size distribution and reduced cell collapse—key indicators of superior material stability and matrix-filler integration.

• Enhanced Thermal Insulation Performance

The primary metric for these materials is thermal performance, which is essential for insulation applications. Testing of the final composite foams demonstrated that the dextrin activation yielded a significant improvement in thermal efficiency. The foams synthesized with the activated fillers achieved lower thermal conductivity values compared to those with unactivated fillers. Specifically, the well-dispersed and chemically integrated VermDex filler provided the most substantial decrease in thermal conductivity. This result directly correlates the success of the glycan surface functionalization with the macroscopic performance of the material, proving that precise interfacial glyco-engineering can dramatically enhance the insulating capabilities of sustainable biopolymer composites.

Conclusion

By demonstrating that a simple, bio-derived glycan like dextrin can be used as an effective, non-toxic surface functionalization agent, the authors have provided a scalable pathway for boosting the efficiency of sustainable polyurethane foams. The innovative application of dextrin to create a robust, chemically bonded interface between bio-polyols and mineral fillers sets a precedent for future bio-composite development. We see exciting potential for this glycan-mediated surface engineering approach to be adapted across other bio-based composites, particularly those derived from marine polysaccharides, paving the way for a new generation of high-performance, environmentally responsible materials.