Quaternary Ammonium Compound (QAC) Treatments

Quaternary ammonium compounds (QACs) are cationic surfactants with the general structure R₄N⁺X⁻ where R groups include long alkyl chains (C12–C18) providing hydrophobic biocidal action. Applied to textiles at 0.5–3.0% owf via pad-dry-cure (150–170°C) or exhaustion, QACs bind ionically or covalently to fiber surfaces. Biocidal mechanism involves electrostatic disruption of negatively charged bacterial cell membranes causing lysis. 3-trimethoxysilylpropyldimethyloctadecyl ammonium chloride (Si-QAC) bonds covalently to hydroxyl groups on cotton and glass, surviving 100+ wash cycles. Effective against gram-positive bacteria, yeasts, and enveloped viruses but less effective against gram-negative and spore-forming bacteria. QAC market in textile applications exceeds $400 million annually.