Hypothesis: Polydopamine (PDA) is widely used as hydrophilic coating for several applications. However, most of the methods studied to improve or manipulate PDA properties are multistep and time-consuming, and there is a need for versatile strategies aimed at controlling and modifying the properties of PDA. Experiments: PDA-halloysite nanocomposites were produced under different oxidation conditions in alkaline and acidic media and were characterized by UV-visible and attenuated total refraction-Fourier Transform Infrared spectroscopies, thermogravimetric analysis, porosimetry, scanning electron microscopy, X-ray diffraction and contact angle measurements against the reference PDA polymer. Findings: Inclusion of the inorganic halloysite nanofiller in the PDA component was found to affect the thermal properties of the nanocomposite as well as its structure, depending on the experimental conditions. The ability of the nanocomposites to adsorb organic dyes as possible membrane coatings for environmental remediation was also investigated by different models, suggesting promising applications as adsorbents for the treatment of wastewaters. (C) 2019 Elsevier Inc. All rights reserved.