The effect of substitute nature on the effectiveness of boron-nitrogen wood preservatives and flame retardants

Introduction. Antiseptic and antipyretic treatment of wood is a prerequisite for its use in modern construction technologies. The use of boron compounds for these purposes has a significant advantage: the formation of stable chemical bonds between the molecules of the modifiers and the hydroxyl groups of the main components of wood (cellulose and lignin) due to boron-amine coordination on the surface of the modified material. By changing the chemical composition of boron-based modifiers, it is possible to control the properties of the surface of modified wood. In this regard, the aim of the study was to develop the optimal composition of boron-based modifiers that would provide long-lasting and effective protection against microorganisms and elevated temperatures while preserving the unique natural properties of pine wood. Methods and materials. The study was carried out using methods of thermal analysis, evaluation of the fire-retardant effectiveness of boron compounds, and determination of the fungus resistance of pine wood samples modified with boron compounds. Results. Boron compounds, in which one hydroxyl group at the boron atom is replaced by a phenyl radical, showed higher effectiveness against mold and wood-destroying fungi and provided the second group of fire protection effectiveness at lower concentrations compared to boron-nitrogen compounds with three hydroxyl groups at the boron atom. Discussion. The introduction of a phenyl radical into boron-nitrogen compounds sharply increases their effectiveness as antiseptics and flame retardants, allowing a fivefold reduction in working concentration without loss of protective properties. Low concentrations of phenylborates (5–10%) reduce processing costs. The minimum concentration of modifiers minimizes the impact on the natural structure of the material. Stable coordination bonds between boron-nitrogen compounds and cellulose and lignin prevent the leaching of reagents. Phenylborate-based compositions are optimal for the comprehensive protection of lignocellulosic materials in construction in accordance with environmental requirements. Conclusion. The study proved that the nature of the substituent in boron compounds is a decisive factor in their effectiveness. Phenyl-containing boron-nitrogen compounds combine high biocidal activity, thermal stability, and fire protection at minimum concentrations, offering an economically and environmentally sustainable solution for wood modification.