Preparation And Characterization Of PDA NPs And Its Application In The Preparation Of TFC Membranes By Interfacial Polymerization

Recently, bionic researchers found that mussels can strongly attach to diverse substrates with high binding strength, even on wet surfaces. The major origins of the extraordinarily robust adhesion are L-DOPA and lysine-enriched proteins. On the basis of these findings, the dopamine, with a molecular structure similar to that of DOPA, moved into the spotlight. Our previous research has found that dopamine can form melanin-like polydopamine nanoparticles (PDA NPs) in solution spontaneously.In this paper, we prepared the catecholic derivates NPs in different experimental conditions and enhance the permeability of thin-film composite polyamide membranes by entrapping the PDA NPs into the functional layer. The main contents and results are summarized as follows:(1) Dopamine is known to be able to undergo oxidation polymerization and crosslinking reaction in the aqueous solution, forming melanin-like polydopamine nanoparticles (PDA NPs) in solution spontaneously. In this part, we prepared the PDA NPs in different experimental conditions by solution polymerization. The obtained catecholic derivates NPs were characterized by Fourier transform infrared spectroscopy, dynamic light scattering, ultraviolet spectrophotometry (UV-vis), transmission electron microscopy (TEM). And the effects of different experimental conditions on the morphologies and sizes of the PDA NPs were inspected. The experimental results provided a better understanding of polymerization mechanism of catecholic derivates NPs but also effective strategies for exploiting the properties of catecholic derivates to create advanced functional materials.(2) PDA NPs’chemical structure incorporates many functional groups such as catechol, amine, and imine. These functional groups can react with various functional molecules containing-NH2,-NH-or-SH under mild conditions, which allowed further functionalization of polyamide membranes. In this part,we aim to enhance the permeability of thin-film composite polyamide membranes by entrapping PDA NPs into polyamide functional layer.The polyamide membranes were prepared by interfacial polymerization of m-phenylenediamine(MPD) and trimesoyl chloride(TMC) on polysulphone (PSF) support membranes with adding PDA NPs addition in the MPD aqueous solution. It was found that the water flux, hydrophilicity of the polyamide membranes were improved after the incorporation of PDA NPs.The water permeability was nearly double that of polyamide membranes with equivalent solute rejections.The results indicated that the structures and performances of polyamide membranes were affected significantly by the addition of PDA NPs.