Characterization and Release Mechanisms of Aerogel-Encapsulated Biocide Crystals for Low-Loading and High-Utilization Antifouling Coatings

Abstract

Silica aerogel-encapsulated biocide crystals can potentially enhance the protection efficiency of antifouling coatings, thereby lowering the impact on nontarget aquatic life. In the present study, copper pyrithione (CuPT) crystals are encapsulated by silica aerogel to obtain loadings of 50–80 wt % CuPT. For optimal design of the heterogeneous particles and mapping of the underlying biocide release mechanisms, the aerogel-encapsulated biocide crystals are characterized by scanning (transmission) electron microscopy, energy-dispersive X-ray spectroscopy, thermal gravimetric analysis, mercury intrusion porosity, Brunauer–Emmett–Teller analysis, and light scattering. The microscopic examination demonstrates that the elongated CuPT crystals are encapsulated by a thin highly porous silica layer. When varying the CuPT loading of the aerogels, it is possible to tune the particle size, pore volume, and specific surface area of the aerogels. Furthermore, this study suggests that the hydrophilic aerogel-encapsulated CuPT, when used in antifouling coatings, attracts seawater and contributes to an efficient controlled release of active CuPT.

Silica aerogel-encapsulated biocide crystals for low-loading antifouling coatings: rheology, water absorption, hardness, and biofouling protection

“…When loading with silica aerogels, the effect, as a result of a reduced porous silica contribution, was reduced. 24 Dynamic viscosity measurements, one day after production and again after 48 days, on the coating series containing aerogels with varying CuPT-loading, were also performed. Table 5 shows the viscosity measured at shear rates of 0.5 and 6 s -1 .…”

“…This is attributed to the higher content of overall porous encapsulating silica material. When increasing the CuPT-loading of the aerogels, the overall silica content, as well as the total pore volume, is reduced 24 . As a result of a reduced pore volume, a larger proportion of the binder material (mainly rosin) of the coating is present in the pores of the aerogels, leading to a higher PVC.…”

“…22,23 3 When embedded in a rosin-based antifouling coating, a novel encapsulation technology, based on porous silica aerogels, can improve the utilization of copper pyrithione (CuPT), thereby minimizing excessive use of biocides. 24 With a higher utilization of CuPT, it is believed that the Cu2O concentration can be significantly reduced, compared to commercial antifouling coatings, without compromising the antifouling performance. In addition, it is believed that the aerogels retain an adequate water absorption, and a continuous organic biocide release, even with a low Cu2O concentration in the coating.…”

Development of Antifouling Coatings Based on Quaternary Ammonium Compounds through a Multilayer Approach

“…The nets covered with the Econea/PDDA 16 (diallyldimethylammonium chloride) nanoparticles prevented biofouling and mesh occlusion on the nets compared to the other coatings. Frydenberg et al [ 17 ] encapsulated copper pyrithione (CuPT) crystals by silica aerogel to obtain loadings of 50−80 % wt. CuPT.…”

Preparation of Thifluzamide Polylactic Acid Glycolic Acid Copolymer Microspheres and Its Effect on the Growth of Cucumber Seedlings

“…Compared with other formulations, the controlled-release system has unique advantages, such as good targeting, slow release, high loading rate, and reduced toxicity. It has been applied to practice as a novel pesticide delivery system and extensively studied in the fields of medicine and biology [ 13 , 14 ]. For example, fungicide retention in encapsulation can reduce the reactivity with external factors, improve the physicochemical properties of active compounds, and enhance the bioavailability of active compounds [ 15 , 16 ].…”