Flame sprayed environmentally friendly high density polyethylene (HDPE)-capsaicin composite coatings for marine antifouling applications

Marine biofouling has emerged as worldwide serious problems for artificial marine infrastructures. Among the measures taken so far to solve the abovementioned problems, construction of an antifouling layer has been proven to be effective in offering long-term antifouling performances. Antifouling based on the use of biocides is the most important method in modern maritime industries. While tributyltin (TBT)-based self-polishing coatings are being replaced by other biocide-releasing coatings, the environmental toxicity of these compounds is also under scrutiny. Therefore, there is a significant interest in developing non-toxic technologies. Green biocides can also be extracted from many types of organisms including terrestrial plants, sea creatures and bacteria. The capsaicin was extracted from chili pepper. In this study, flame sprayed high density polyethylene (HDPE)-capsaicin composite coatings were developed for marine antifouling applications. Capsaicin powder were fixed by polymer-based substrate and distributed evenly. Antifouling performances of the films were assessed by examining survival and colonization behaviors of E. coli and Bacillus sp. bacteria and Phaeodactylum tricomutum. Antifouling test indicated excellent antibacterial properties of HDPE-capsaicin composite coatings against both gram-negative Escherichia coli and gram-positive marine Bacillus sp. bacteria. Excellent antifouling performances against bacteria and algae of the thermal sprayed composite coatings give clear insight into their potential applications as environmentally friendly antifouling layers in the marine environment. (C) 2018 Elsevier B.V. All rights reserved.