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This study addresses one of the most common problems faced by the marine sector, namely the accumulation of organic matter and organisms on submerged surfaces. This biological phenomenon causes structural problems in aquatic systems and its mitigation implies a large economic outlay for marine aquaculture industry. Antifouling paints are being developed to help control this undesirable process; however, these treatments are problematic as they degrade and release biocides and heavy metals into the environment. In this context, our study focuses on developing more environmentally friendly antifouling strategies. For this purpose, we designed high-density polyethylene (HDPE) material functionalized with different copper compounds or silica, and subsequently tested their effects on biofilm formation by aquatic organisms at both laboratory and pilot scale. Bacterial species (Vibrio harveyi and Cellulophaga lytica) and diatoms (Nitzschia ovalis) known for producing biofilm were used. Our study revealed that material including copper pyrithione (CuPT) was highly effective in inhibiting bacterial and algal biofilm formation. Moreover, the ecotoxicological study covering three trophic levels (bacteria, algae and rotifers) indicated that none of the materials developed and tested herein was toxic. HDPE is easily moldable and suitable to produce built-in aquatic structures, and our results show that its functionalization with CuPT greatly improves its antifouling capacity. These findings represent a step forward in the fight against fouling in marine environments.

HDPE is a semi-crystalline thermoplastic polymer, with remarkable physical properties such as high chemical resistivity, high impact strength, and high modulus. Compared to the other semi-crystalline polymers, HDPE mostly possesses a high crystallinity, due to which, it exhibits a unique combination of mechanical and chemical resistance properties. In the present work, we have characterized the crystalline spherulites of neat and formulated HDPE compositions thoroughly characterized by different electron microscopy techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM). One of the critical steps to obtaining well-resolved SEM images is the sample preparation that typically involves the etching process to elucidate the crystalline spherulites. Though such traditional methodology can effectively be used for neat HDPE, it leads to the creation of undesirable experimental artifacts when used to investigate formulated HDPE compositions. An alternate TEM-based method provides clear images without any artifacts, apart from being a direct and green method and taking relatively a lesser measurement time. • The paper summarizes a novel, simple and green method for imaging the spherulitic structures in HDPE. • While the lamellae are ubiquitous in the HDPE, they cannot differentiate between monomodal, bi-modal or multimodal HDPE. • In the TEM method, we are able to clearly elucidate the crystalline spherulites of neat and blended HPDE. • The TEM method avoids the use of acids for etching, heavy metal stains and takes less time. • This method can be used to study the effect (on crystalline morphology) of incorporating new additives, monomers or comonomers to HDPE. [ABSTRACT FROM AUTHOR]