Dopamine-based polyisoquinoline derivative: Facile preparation and dual applications in efficient iodine capture and Ag nanoparticles immobilization

Apart from the traditional polydopamine (PDA), which produced by the self-polymerization of dopamine (DA), there are scarce reports regarding the construction of functional polymer by directly using DA as the starting material. The relevant work could provide a beneficial supplement for further expanding the downstream utilization of DA’s chemical activity. In this study, a type of novel DA-based polytetrahydroisoquinoline derivative (PDT) was facilely prepared by metal-free Pictet-Spengler (P-S)/Mannich cascade reaction by using dopamine and formaldehyde as starting substrates. The influence of formaldehyde dosage and the introduction of triethylamine on the preparation of PDT was discussed, and the chemical structure and elementary properties of PDT were systematically characterized here. The iodine adsorption performance of PDT was investigated. Experimental results showed that PDT could effectively adsorb iodine in both steam (75 oC, under atmospheric pressure) and solution (in cyclohexane) states, and the corresponding equilibrium adsorption capacities reached ∼ 4.07 and 1.21 g g-1, respectively. The adsorption mechanism was investigated by X-ray photoelectron spectroscopy (XPS), Raman and FT-IR analyses. Experimental results suggested that N/O-containing units (tertiary amine and phenolic hydroxyl) and aromatic frameworks in the structure of PDT participated in the adsorption process. In addition, polymer/silver nanoparticles (AgNPs) composite (PDT-AgNPs) was prepared by using PDT as AgNPs’ support, and the catalytic performance of PDT-AgNPs for the reduction of p-nitrophenol, an aqueous pollutant, was investigated. Corresponding results told that PDT-AgNPs illustrated good catalytic activity (with reaction constant Kc of ∼ 17.82 L s-1 g-1) and cycling stability.