Magnesium oxysulfate cement-based wood fiberboard (MOSCWF) is a promising, eco-friendly building material; however, its application is severely limited by its intrinsic moisture sensitivity and insufficient mechanical strength. Here, we investigated the synergistic modification of MOSCWF using organic phosphonic acid 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) combined with cationic surfactants: dodecyl trimethyl ammonium chloride (DTAC) and stearyl trimethyl ammonium chloride (STAC). Experimental results demonstrated that the synergistic combination of HEDP and STAC effectively optimized the phase evolution and reinforced the inorganic-organic interface, leading to a significantly densified microstructure. The optimized composites exhibited enhanced mechanical performance, achieving a 79.7% increase in the modulus of rupture (MOR) and a 62.7% increase in the modulus of elasticity (MOE) compared with the control. Water resistance was also notably enhanced, with 24 h linear and thickness swelling rates (LS and TS) reduced by 49.2% and 44.4%, respectively. This study provides a robust theoretical basis for fabricating high-performance, water-resistant MOSCWF through dual-mechanism regulation. • HEDP and STAC synergistically optimize phase evolution and interfacial properties. • Surfactant pretreatment constructs ordered hydrophobic films on wood fibers. • STAC reinforces interfaces via electrostatic adsorption and hydrogen bonding. • Synergistic modification yields superior water resistance and mechanical performance.
Fu et al. (Sun,) studied this question.