polymers Article Production and Characterization of Polyethylene Terephthalate Nanoparticles Francesca Lionetto 1, * , Carola Esposito Corcione 1 , Aurora Rizzo 2 and Alfonso Maffezzoli 1   Citation: Lionetto, F.; Esposito Corcione, C.; Rizzo, A.; Maffezzoli, A. Production and Characterization of Polyethylene Terephthalate Nanoparticles. Polymers 2021, 13, 3745. https://doi.org/10.3390/ polym13213745 Academic Editor: Arunas Ramanavicius Received: 31 August 2021 Accepted: 25 October 2021 Published: 29 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Engineering for Innovation, University of Salento, Via Arnesano, 73100 Lecce, Italy; carola.corcione@unisalento.it (C.E.C.); alfonso.maffezzoli@unisalento.it (A.M.) 2 CNR NANOTEC—Istituto di Nanotecnologia, c/o Campus Ecotekne, Via Monteroni, 73100 Lecce, Italy; aurora.rizzo@nanotec.cnr.it * Correspondence: francesca.lionetto@unisalento.it Abstract: Microplastic (MP) pollution represents one of the biggest environmental problems that is further exacerbated by the continuous degradation in the marine environment of MPs to nanoplastics (NPs). The most diffuse plastics in oceans are commodity polymers, mainly thermoplastics widely used for packaging, such as polyethylene terephthalate (PET). However, the huge interest in the chemical vector role of micro/nanoplastics, their fate and negative effects on the environment and human health is still under discussion and the research is still sparse due also to the difficulties of sampling MPs and NPs from the environment or producing NPs in laboratory. Moreover, the research on MPs and NPs pollution relies on the availability of engineered nanoparticles similar to those present in the marine environment for toxicological, transport and adsorption studies in biological tissues as well as for wastewater remediation studies. This work aims to develop an easy, fast and scalable procedure for the production of representative model nanoplastics from PET pellets. The proposed method, based on a simple and economic milling process, has been optimized considering the peculiarities of the polymer. The results demonstrated the reliability of the method for preparing particle suspensions for aquatic microplastic research, with evident advantages compared to the present literature procedures, such as low cost, the absence of liquid nitrogen, the short production time, the high yield of the process, stability, reproducibility and polydisperse size distribution of the produced water dispersed nanometric PET. Keywords: poly (ethylene terephthalate) nanoplastics; model nanoplastics; microplastics; annealing; DSC; marine plastics; ocean pollution; ball milling; nanoplastic formation 1. Introduction Nowadays, rapid population growth and the daily utilization of polymers for manu- facturing non-reusable stuffs for various applications, such as packaging, cosmetics, textiles, detergents, greenhouse films, mulches, fishing nets, etc. cause large amounts of waste products and issues relating to their managing and disposal [1–4]. As a consequence, world production of municipal solid waste went from 1.3 billion tons in 1990 to 3.81 billion tons after 25 years [5], and plastics are a considerable percentage of this latter value [6,7]. In particular, in 2018, almost 29.1 million tons of plastic waste were collected in the European Union, of which 42.6% were incinerated with energy recovery through energy-from-waste, 32.5% were recycled and 24.9% were landfilled [8]. In addition, the waste management issues due to plastics can be ascribed not only to their excessive use but also to their small service life and slow degradation time [9]. Between 4.8 and 12.7 million tons of plastic waste are dispersed in the ocean each year [10]. Most of them derive from land-based activities, but a growing percentage arises from fishery activities waste [11]. Within Europe, around 85% of marine litter found on beaches is plastic. Around 43% of this marine litter is single use plastic, and 27% is fishing gear [12]. Polymers 2021, 13, 3745. https://doi.org/10.3390/polym13213745 https://www.mdpi.com/journal/polymers