Hybrid Inorganic and Bio-Based Composites and Their Evaluation for Biological Resistance

This work investigates the development of inorganic polymeric/ network-forming coatings with enhanced biological resistance for bio-based insulation panels. The coatings are water-based systems synthesized via acid-initiated network formation using inorganic precursors, producing a continuous and chemically adhered protective matrix. Particular emphasis was placed on the incorporation of bio-based and biodegradable functional additives within an inorganic framework to achieve a balance between performance and sustainability.

A combination of inorganic fillers, organic components, and biopolymers were incorporated to enhance coating durability, barrier properties, interfacial adhesion and provide synergistic antifungal activity. Coating porosity was systematically tailored by varying key synthesis parameters, including acidity, solvent composition, and inorganic filler content, enabling investigation of structure–property relationships.

Hygroscopic behaviour was evaluated under high humidity conditions (~96% RH) and correlated with biological performance assessed via in-house mould resistance and disk diffusion assays. Results indicate that a better interconnected inorganic network and lower moisture uptake improve resistance to microbial colonisation, whereas highly hygroscopic systems promote growth.

Additionally, encapsulation of naturally derived bioactive compounds, dispersed homogeneously within the coating matrix were studied for sustained antifungal functionality. The primary mechanisms of action are proposed to involve disruption of microbial cell integrity and the formation of barrier layers that inhibit microbial proliferation.