Polyquaternium-6

Hansen, Anna Magdalene Brun, et al. Journal of Hazardous Materials Letters 5 (2024): 100095.

Polyquaternium-6 (PQ-6), a high charge density cationic polymer widely used in personal care and industrial applications, has been evaluated for its potential toxicological effects on aquatic organisms. Continuous exposure of zebrafish larvae to PQ-6 revealed significant alterations in immune-gene expression and lipid metabolism, providing mechanistic insights into its biological impact.

Lipidomic analysis indicated severe depletion of key lipids, including lyso-glycerophosphocholines and ceramides, in 12-day post-fertilization larvae, suggesting membrane perturbations and potential disruption of cell signaling pathways. Quantitative PCR analyses further demonstrated inflammatory responses characterized by significant up-regulation of tnfα and saa at high PQ-6 concentrations, while interleukin genes such as il1β exhibited concentration- and development stage-dependent regulation. Notably, acute exposure to the highest tested concentration (0.4 mg/L) induced distress behaviors, necessitating euthanasia in some larvae, highlighting dose-dependent toxicity.

The inflammatory effects were more pronounced at early developmental stages (5 dpf), implicating PQ-6 in both acute and potentially chronic immune modulation. Mechanistically, these effects appear to be driven by non-specific interactions with cell membranes, leading to oxidative stress and reactive oxygen species (ROS) generation, with narcosis-like lethality hypothesized at higher exposures.

These findings demonstrate that PQ-6, despite its industrial ubiquity, can elicit substantial immunotoxic and lipidomic perturbations in aquatic organisms. The study underscores the importance of charge density in dictating polymer toxicity and provides a critical framework for assessing environmental safety of water-soluble cationic polymers, supporting more informed regulation and risk assessment in aquatic ecosystems.

Liu, Shuzhen, et al. Journal of Porous Materials 15.3 (2008): 295-301.

Polyquaternium-6 (PQ-6), a water-soluble cationic polymer, has been successfully applied as a low-cost organic template in the synthesis of EMT-rich faujasite zeolite, eliminating the need for expensive crown ethers such as 18-crown-6. In this approach, water glass served as a cost-effective silica source, replacing conventional silica sol, while NaAlO₂ and NaOH provided the alumina and alkalinity required for gel formation.

The synthesis involved aging an aluminosilicate solution, followed by incorporation of PQ-6 into the precursor mixture, and hydrothermal crystallization at 100–110 °C for 2–14 days. X-ray diffraction (XRD) confirmed the presence of EMT structure alongside Y zeolite, with EMT purity reaching 70–80%. Scanning electron microscopy (SEM) revealed hexagonal crystal morphologies characteristic of EMT, while thermogravimetric and differential thermal analyses (TG-DTA) indicated the decomposition of PQ-6 during calcination, highlighting its critical role as a structure-directing agent.

Functional characterization showed that EMT-rich faujasite exhibited slightly higher acidity compared to Y zeolite, as measured by NH₃ temperature-programmed desorption (NH₃-TPD). Catalytic testing via cumene cracking demonstrated superior activity of the EMT-rich material, confirming the effectiveness of PQ-6 in directing active zeolite frameworks.

This study establishes polyquaternium-6 as a versatile and economical template for the controlled synthesis of high-purity EMT zeolites with enhanced catalytic properties. Its successful application paves the way for more sustainable and cost-efficient preparation of functional faujasite-type zeolites for industrial catalysis and adsorption applications.