Understanding the adsorption behavior of charged molecular species at functionalized polymer interfaces is critical for advancing surface science and material design. Building upon recent advances in polydopamine (PDA) -mediated polymer grafting, we investigated electrostatic adsorption at cationic polymer brush surfaces. Using a grafting-to approach, we covalently attached poly (2-trimethylammonioethyl methacrylate chloride) (PTMAEMA) to PDA-coated stonewool fibers and characterized the resulting charged interface via x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). We employed perfluorooctanoic acid (PFOA) as a model anionic adsorbate to investigate binding at a quaternary amine-functionalized surface. Batch equilibrium sorption studies revealed concentration-dependent adsorption kinetics, achieving three times higher binding affinity for PTMAEMA-functionalized fibers at concentrations ranging from 0. 5 to 5. 0 g L^−1, with equilibrium reached within 10 min. XPS analysis confirmed the successful surface functionalization with distinct nitrogen environments at 395. 5 eV (PDA) and 398. 5 eV (quaternary nitrogen), while thermogravimetric data indicated an organic loading of close to 28%. Our findings demonstrate that PDA-mediated polymer grafting provides a versatile platform for creating well-defined charged interfaces with tunable adsorption characteristics, and provides a methodology to explore fundamental adsorption phenomena at polymer-liquid interfaces.
Morrissey et al. (Thu,) studied this question.