Antifouling Research Articles

TiO2-PAA-SiO2 pearl chain blend modified polyvinylidene fluoride ultrafiltration membrane with excellent oil-water separation, anti fouling performance and durability

ABSTRACT In this work, a new type of composite nanoparticles, ‘pearl chain’, was developed by linking titanium dioxide and silicon dioxide by polyacrylic acid polymer chains, and the prepared TiO2-PAA-SiO2 composite nanoparticles were analysed by SEM, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis, zeta potential, x-ray diffraction, etc. The success of this work was verified by the successful linking of TiO2-PAA-SiO2 composite nanoparticles.TiO2-PAA-SiO2 composite nanoparticles were analysed to verify the successful attachment of pearl chains. The obtained TiO2-PAA-SiO2 were subsequently blended in different ratios to prepare polyvinylidene fluoride (PVDF) ultrafiltration membranes. The membrane performance was tested by porosity and water contact angle measurements, scanning electron microscopy, as well as experiments using bovine serum proteins and MTBE interception. The results showed that when a certain amount of TiO2-PAA-SiO2 was added, the surface wettability, porosity and permeability of the prepared modified composite membranes were significantly improved, and the BSA adsorption rate was increased from 71.59% to 80.86%, and the retention rate of MTBE was increased by 77%, in addition to showing a better anti-pollution effect (FRR: 91.07%). It was finally concluded that the prepared membranes embedded with 1.0 wt.% TiO2-PAA-SiO2 nanofillers showed good overall filtration performance, better contamination resistance and remarkable durability. The present work successfully demonstrated the feasibility of using polyacrylic acid chemical chains to connect nanoparticles with different functions to prevent particle loss and substantially enhance membrane performance, which is valuable for bridging connection of composite nanoparticles and exploring the development of high-performance ultrafiltration membranes.

Oligohexamethylene Guanidine Derivative as a Means to Prevent Biological Fouling of a Polymer-Based Composite Optical Oxygen Sensor.

The use of biocidal agents is a common practice for protection against biofouling in biomass-rich environments. In this paper, oligohexamethyleneguanidine (OHMG) polymer, known for its biocidal properties, was further modified with para-aminosalicylic acid (PAS) to enhance its properties against microorganisms coated with a lipid membrane. The structure of the product was confirmed by 1H NMR, 13C NMR, and FTIR spectroscopy. The values of the minimum inhibitory concentration (MIC) against Mycobacterium smegmatis ATCC 607 and Pseudomonas chlororaphis 449 were found to be 1.40 and 1.05 μg/mL, respectively. The synthesized substance was used as an additive to the polymer matrix of the composite optical oxygen sensor material. A series of samples with different contents of OHMG-PAS was prepared using a co-dissolution method implying the fabrication of a coating from a solution containing both polymers. It turned out that the mutual influence of the components significantly affects the distribution of the indicator in the matrix, surface morphology, and contact angle. The optimal polymer content turned out to be wt.3%, at which point the water contact angle reaches almost 122°, and the fouling rate decreases by almost five times, which is confirmed by both the respiratory MTT assay and confocal microscopy with staining. This opens up prospects for creating stable and biofouling-resistant sensor elements for use in air tanks or seawater.

Electrocatalytic aptasensor for bacterial detection exploiting ferricyanide reduction by methylene blue on mixed PEG/aptamer monolayers

Pathogen-triggered infections are the most severe global threat to human health, and to provide their timely treatment and prevention, robust methods for rapid and reliable identification of pathogenic microorganisms are required. Here, we have developed a fast and inexpensive electrocatalytic aptamer assay enabling specific and ultrasensitive detection of E. coli. E. coli, a biomarker of environmental contamination and infections, was captured on the mixed aptamer/thiolated PEG self-assembled monolayers formed on electrochemically pre-treated gold screen-printed electrodes (SPE). Signals from aptamer - E. coli binding were amplified by electrocatalytic reduction of ferricyanide mediated by methylene blue (MB) adsorbed on bacterial and aptamer surfaces. PEG operated as an antifouling agent and inhibited direct (not MB-mediated) discharge of ferricyanide. The assay allowed from 10 to 1000 CFU mL−1E. coli detection in 30 min, with no interference from B. subtilis, in buffer and artificial urine samples. This electrocatalytic approach is fast, specific, sensitive, and can be used directly in in-field and point-of-care applications for analysis of bacteria in human environment.

Antifouling performance of TiO2-based SiO2–Na2O–K2O glass-ceramic coatings in marine environments

Biofouling refers to the accumulation of organisms on artificial surfaces. This phenomenon poses significant challenges in industrial processes, including reduced energy efficiency and increased fuel consumption. Antifouling coating systems are designed to prevent biofouling on artificial surfaces. Currently, there is a growing focus on developing eco-friendly solutions to mitigate the environmental impact of these antifouling coatings. In this study, the antifouling (AF) performance of a TiO2-based borosilicate glass-ceramic coating (Ti-GCC) system was evaluated in terms of barnacle settlement on the coating surface. To create anatase crystals in a coating, a special precursor glass (Ti-PG) formulation, Na2O–K2O–TiO2–B2O3–Al2O3–SiO2–P2O5–F, with <10 % of Na2O and 20 % TiO2 along with other components was used. The Ti-PG was characterised through X-ray fluorescence (XRF) spectroscopy to determine the chemical composition. The milled Ti-PG with additives was applied on a steel substrate using a spray gun and devitrified at 550 °C and 860 °C for 6 min. The phase determination, surface evaluation, thermal behaviour analysis, and AF evaluation of the Ti-GCC were conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), non-contact optical profilometry (NCOP), and thermogravimetric-differential thermal analysis (TG-DTA). The anatase crystal was determined to exist in the Ti-GCC structure. Although the AF evaluation results revealed that the Ti-GCC system had barnacle settlement (73.9 barnacles/cm2), the surface could be easily cleaned. Additionally, the EDS results confirmed that no biofilm was formed on the Ti-GCC's surface. The roughness of the surface before the AF evaluation and after the cleaning procedure was measured using NCOP, and the difference in surface roughness was examined. The small difference in the roughness of the surfaces suggested that the Ti-GCC system exhibited resistance to microbially induced corrosion (MIC). Furthermore, EDS mapping did not provide any evidence of barnacle diffusion into the coated layer. Furthermore, the thickness measurements of the cross-sectional area of the Ti-GCC before and after AF evaluation through SEM proved that coating depletion did not occur.

Settlement behavior and mechanism of Navicula sp. on WLAP/PDMS composite coating under simulative diurnal alternation, constant light and dark conditions

Marine biological fouling is a persistent issue facing the marine industries, which not only causes damage to the underwater facilities but also results in substantial financial losses. Diatoms are one of the most harmful polluters in the ocean. In this paper, novel antifouling coatings inspired by fluorescent coral were reported. Waterproof long afterglow phosphors (WLAP) were introduced into the cross-linked network of polydimethylsiloxane (PDMS). WLAP can absorb and store light energy during the day and emit weak fluorescence at night, which affects the normal physiological activities of diatoms. Through the synergistic mechanism of low surface energy and fluorescence antifouling, excellent antifouling performance is achieved throughout the day. The settlement behavior of Navicula sp. on WLAP/PDMS composite coatings was studied under simulative diurnal alternation, continuous light, and dark conditions. The results demonstrated that the adhesion of diatoms on WLAP/PDMS composite coatings decreased significantly under simulative diurnal alternation. The inhibition effect of the sky-blue composite coating was the most obvious. The attachment reduction rate (ARR) was 35.4% compared with the blank control coating, and the diatom removal rate (DRR) after washing was 42.3%. Constant light conditions also affect the normal physiological activities of diatoms, while the feeble light of coatings is covered. In continuous dark condition, the antifouling abilities of coatings mainly depend on their low surface energy. The composite waterborne coatings prepared in this research is non-toxic and eco-friendly and can recycle solar energy, which supply a new direction for enhancing the static antifouling ability of coatings and an environmentally friendly antifouling strategy, and becomes an important step for sustainable development.

Alteration of microbial mediated carbon cycle and antibiotic resistance genes during plastisphere formation in coastal area

Microorganisms can attach on the surface of microplastics (MPs) through biological fouling process to form a diverse community called the "plastisphere", which has attracted extensive attention. Although the microbial structure and composition of biofilm have been studied, the knowledge of its microbial function and ecological risk is still limited. In this study, we investigated how the surface properties of MPs affect the biofilm communities and metabolic features under different environmental conditions, and explored the biofilm enrichment of antibiotic resistance genes (ARGs). The results showed that the incubation time, habitat and MPs aging state significantly influenced the structure and composition of biofilm microbial communities, and a small amount of pathogens have been found in the MPs-attached biofilm. The microbial carbon utilization capacity of the biofilm in different incubation habitats varies greatly with highest metabolism capacity appear in the river. The utilization efficiency of different carbon sources is polymer > carbohydrate > amino acid > carboxylic acids > amine/amide, which indicates that the biofilm communities have selectivity between different types of carbon sources. More importantly, ARGs were detected in all the MPs samples and showed a trend of estuary > river > marine. The aged MPs can accumulate more ARGs than the virgin items. In general, MPs in the aquatic environment may become a carrier for pathogens and ARGs to spread to other environment, which may enhance their potential risks to the ecosystem and human health.

Enhancing membrane separation performance in the conditions of different water electrical conductivity and fouling types via surface grafting modification of a nanofiltration membrane, NF90

A commercialized and widely applied nanofiltration membrane, NF90, was in-situ modified through a surface grafting modification method by using 3-sulfopropyl methacrylate potassium salt and initiators. The effects of water electrical conductivity (EC) and fouling types on membrane separation efficiency were examined before and after membrane modification. Results reveal that both the pristine membrane (PTM) and surface grafting modification membrane (SGMM) had a declining permeate flux and salt (NaCl) removal efficiency but an increasing trend of pharmaceuticals and personal care products (PPCPs) removal with increasing water EC from 250 to 10,000 μs cm−1. However, SGMM exhibited a slightly declining permeate flux but 13%–17% and 1%–42% higher rejection of salt and PPCPs, respectively, compared with PTM, due to electrostatic repulsion and size exclusion provided by the grafted polymer. After sodium alginate (SA) and humic acid (HA) fouling, SGMM had 17%–26% and 16%–32% higher salt rejection and 1%–12% and 1%–51% greater PPCP removal, respectively, compared with PTM due to the additional steric barrier layer contributed by the foulants. The successful grafting and increasing hydrophilicity of the SGMM were confirmed by contact angle analysis, which was beneficial for mitigating membrane fouling. Overall, the proposed in-situ surface grafting modification of NF90 can considerably mitigate organic and biological fouling while raising the rejection of salt and PPCPs at different background water EC, which is beneficial for practical applications in producing clean and high quality water for consumers.

New Insights on Biological Activities, Chemical Compositions, and Classifications of Marine Actinomycetes Antifouling Agents.

Biofouling is the assemblage of undesirable biological materials and macro-organisms (barnacles, mussels, etc.) on submerged surfaces, which has unfavorable impacts on the economy and maritime environments. Recently, research efforts have focused on isolating natural, eco-friendly antifouling agents to counteract the toxicities of synthetic antifouling agents. Marine actinomycetes produce a multitude of active metabolites, some of which acquire antifouling properties. These antifouling compounds have chemical structures that fall under the terpenoids, polyketides, furanones, and alkaloids chemical groups. These compounds demonstrate eminent antimicrobial vigor associated with antiquorum sensing and antibiofilm potentialities against both Gram-positive and -negative bacteria. They have also constrained larval settlements and the acetylcholinesterase enzyme, suggesting a strong anti-macrofouling activity. Despite their promising in vitro and in vivo biological activities, scaled-up production of natural antifouling agents retrieved from marine actinomycetes remains inapplicable and challenging. This might be attributed to their relatively low yield, the unreliability of in vitro tests, and the need for optimization before scaled-up manufacturing. This review will focus on some of the most recent marine actinomycete-derived antifouling agents, featuring their biological activities and chemical varieties after providing a quick overview of the disadvantages of fouling and commercially available synthetic antifouling agents. It will also offer different prospects of optimizations and analysis to scale up their industrial manufacturing for potential usage as antifouling coatings and antimicrobial and therapeutic agents.

Influence of Light Conditions on the Antibacterial Performance and Mechanism of Waterborne Fluorescent Coatings Based on Waterproof Long Afterglow Phosphors/PDMS Composites.

Marine microbial adhesion is the fundamental cause of large-scale biological fouling. Low surface energy coatings can prevent marine installations from biofouling; nevertheless, their static antifouling abilities are limited in the absence of shear forces produced by seawater. Novel waterborne antifouling coatings inspired by fluorescent coral were reported in this paper. Waterproof long afterglow phosphors (WLAP) were introduced into waterborne silicone elastomers by the physical blending method. The composite coatings store energy during the day, and the various colors of light emitted at night affect the regular physiological activities of marine bacteria. Due to the synergistic effect of fouling-release and fluorescence antifouling, the WLAP/polydimethylsiloxane (PDMS) composite coating showed excellent antifouling abilities. The antibacterial performance of coatings was tested under simulated day-night alternation, continuous light, and constant dark conditions, respectively. The results illustrated that the antibacterial performance of composite coatings under simulated day-night alternation conditions was significantly better than that under continuous light or darkness. The weak lights emitted by the coating can effectively inhibit the adhesion of bacteria. C-SB/PDMS showed the best antibacterial effect, with a bacterial adhesion rate (BAR) of only 3.7%. Constant strong light also affects the normal physiological behavior of bacteria, and the weak light of coatings was covered. The antibacterial ability of coatings primarily relied on their surface properties under continuous dark conditions. The fluorescent effect played a vital role in the synergetic antifouling mechanism. This study enhanced the static antifouling abilities of coatings and provided a new direction for environmentally friendly and long-acting marine antifouling coatings.

Qualitative analysis and simulations of the biological fouling problem on filtration membranes

The mitigation of fouling formation and development in filtration systems represents the most critical aspect for water treatment, as it naturally affects both the operational costs for management procedures, and the duration of filtration devices. As it constitutes an artificial physical barrier for solid particles retention, membrane systems are perfect environments for the adhesion and development of biological fouling layers, especially in wastewater treatment reactors. Based on recent results, the present work focuses on the qualitative analysis of a mono dimensional continuous model for biofouling dynamics in microfiltration systems. The free boundary problem accounting for the evolution of the biofouling layer during the filtration regimen has been discussed in terms of existence and uniqueness of the solution. The achieved results represent a consistent base for numerical studies related to the correct prediction of transmembrane pressure in membrane systems. Numerical examples related to the heterotrophic–autotrophic interaction occurring in wastewater treatment plants have been presented to highlight the effect of crucial biological aspects, such as extracellular polymeric substances (EPS) accumulation, usually neglected in the classical membrane filtration modeling. The description of biofouling dynamics and membrane performance during the filtration regimen highlight key aspects for microfiltration system management in all industrial applications.

Toxic effects and potential mechanisms of zinc pyrithione (ZPT) exposure on sperm and testicular injury in zebrafish

Zinc pyrithione (ZPT) is widely recognized for its beneficial properties as an antifouling, antibacterial, and antifungal agent. Despite its positive industrial contributions, ZPT has been proven to exhibit toxicity towards various ecosystems, particularly affecting marine life. However, there is still a dearth of comprehensive research on ZPT toxicity and its toxicological mechanism in reproductive systems of aquatic organisms. In our study, we conducted a thorough analysis and unveiled a multitude of abnormalities in zebrafish sperm and testicular tissue caused by ZPT exposure, including a dose-dependent diminishing of testosterone levels, various sperm deformities, decreased sperm concentration and motility, and ROS-induced testicular tissue DNA damage. In addition, our study suggested that ZPT-induced testicular damage is associated with heightened oxidative stress, apoptosis, and possible hyperpolarization of the mitochondrial membrane. Through RNA-seq analysis, a total of 409 DEGs associated with ZPT-induced testicular injury were identified, and the hub gene was determined using a protein-protein interaction network (PPI). The genes and pathways uncovered in this study point to potential mechanisms of ZPT exposure on sperm and testicular injury in zebrafish.

Do biosurfactants as anti-biofilm agents have a future in industrial water systems?

Biofilms are bacterial communities embedded in exopolymeric substances that form on the surfaces of both man-made and natural structures. Biofilm formation in industrial water systems such as cooling towers results in biofouling and biocorrosion and poses a major health concern as well as an economic burden. Traditionally, biofilms in industrial water systems are treated with alternating doses of oxidizing and non-oxidizing biocides, but as resistance increases, higher biocide concentrations are needed. Using chemically synthesized surfactants in combination with biocides is also not a new idea; however, these surfactants are often not biodegradable and lead to accumulation in natural water reservoirs. Biosurfactants have become an essential bioeconomy product for diverse applications; however, reports of their use in combating biofilm-related problems in water management systems is limited to only a few studies. Biosurfactants are powerful anti-biofilm agents and can act as biocides as well as biodispersants. In laboratory settings, the efficacy of biosurfactants as anti-biofilm agents can range between 26% and 99.8%. For example, long-chain rhamnolipids isolated from Burkholderia thailandensis inhibit biofilm formation between 50% and 90%, while a lipopeptide biosurfactant from Bacillus amyloliquefaciens was able to inhibit biofilms up to 96% and 99%. Additionally, biosurfactants can disperse preformed biofilms up to 95.9%. The efficacy of antibiotics can also be increased by between 25% and 50% when combined with biosurfactants, as seen for the V9T14 biosurfactant co-formulated with ampicillin, cefazolin, and tobramycin. In this review, we discuss how biofilms are formed and if biosurfactants, as anti-biofilm agents, have a future in industrial water systems. We then summarize the reported mode of action for biosurfactant molecules and their functionality as biofilm dispersal agents. Finally, we highlight the application of biosurfactants in industrial water systems as anti-fouling and anti-corrosion agents.

Eco-Friendly Capsaicin-Containing Water-Based Antifouling Coatings for Marine Aquaculture

Natural antifoulants have received significant interest in the search for non- or less-toxic antifouling coating systems for marine structures. Capsaicin, a natural compound that can be found in chili peppers, is known as an environmentally friendly antifouling agent with an excellent performance and a low environmental impact. However, controlling its release from the coating matrix is still an issue to be solved. With the aim of developing an eco-friendly antifouling system with prolonged long-term activity, in this study, we incorporated capsaicin in combination with dichlofluanid into water-based acrylic coating formulations. The antifouling activity of the resulting coatings was studied by examining the survival behavior of a Gram-negative marine bacterium Aeromonas Salmonoid ATCC 33658, and the release rate of capsaicin from the paint matrix was also assessed. The combination of 0.75 wt.% capsaicin and 0.75 wt.% dichlofluanid into the same matrix showed an antibacterial performance of up to 99.9% cfu reduction with an antibacterial value R 2.5–3 times higher than those obtained with the single biocides at 1.5 wt.%. The association between the two organic biocides created a synergistic effect on the antifouling performance, further resulting in a prolonged activity.

Eco-friendly polysaccharide coatings for antifouling and drag-reduction and potential application for marine devices

Traditional antifouling agents usually have a certain toxic effect on marine environments and non-target organisms. In this study, Dictyophora indusiata polysaccharide (DIP) was applied as a natural antifouling surface modifier to prepare the surface coating for marine antifouling. Three DIP coatings were prepared: D. indusiata spore polysaccharide (DISP), D. indusiata volva polysaccharide (DIVP), and D. indusiata embryonic body polysaccharide (DIEP). The antifouling, tribological, and anticorrosion behavior of the coatings were examined. Results revealed that the three kinds of DIP coatings had excellent antifouling properties, which could effectively prevent the adhesion of Chlorella and the attachment of water-based and oily stains on the surface. Additionally, the coatings showed great mechanical stability and could maintain an extremely low coefficient of friction (COF < 0.05) after continuous wear. The drag reduction rate of the coated surfaces reached 5%, showing a powerful lubrication performance. Furthermore, the DIP coatings presented an outstanding corrosion resistance, where the equivalent circuit impedances were 4–9 orders of magnitude higher than the control groups. This research showed a promising prospect of surface coating fabrication with DIP for marine devices to achieve the purpose of antifouling and drag reduction.

Research Progress of Natural Products and Their Derivatives in Marine Antifouling.

With the increasing awareness of environmental protection, it is necessary to develop natural product extracts as antifouling (AF) agents for alternatives to toxic biocides or metal-based AF paints to control biofouling. This paper briefly summarizes the latest developments in the natural product extracts and their derivatives or analogues from marine microorganisms to terrestrial plants as AF agents in the last five years. Moreover, this paper discusses the structures-activity relationship of these AF compounds and expands their AF mechanisms. Inspired by the molecular structure of natural products, some derivatives or analogues of natural product extracts and some novel strategies for improving the AF activity of protective coatings have been proposed as guidance for the development of a new generation of environmentally friendly AF agents.

Control of organic and biological fouling of polyethersulfone membrane by blending and surface modification using natural additives

In this study, a modified polyethersulfone (PES) membrane was fabricated by blending collagen (COL) in the PES dope solution and the subsequent coating with chitosan (CHI) – polyphenon from green tea (PGT). The antifouling and antibacterial properties of all prepared membranes were evaluated. The results demonstrated that the CHI and PGT coating on COL-incorporated membrane exhibited enhanced hydrophilicity and flux recovery compared with the pristine PES membrane. The best solute rejection and control of foulant adsorption were observed with the optimized modified membrane (0.3COL@0.6CHI/0.6PGT). Also, the 0.3COL@0.6CHI/0.6PGT membrane showed a predominant inhibition zone area, suggesting the excellent antibacterial properties of the membrane. During surface water filtration, the removal rates of COD, TDS, conductivity, and turbidity were enhanced from 32.2 % to 52.5 %, from 67.2 % to 72.7 %, from 12.9 % to 24.7 %, and from 70.8 % to 92.2 %, respectively, by using the optimized modified membrane. Furthermore, the outstanding performance of membrane stability, in terms of hydrophilicity and antibacterial properties, was also confirmed by water contact angle and inhibition zone analyses. This study provided an effective and environmentally-friendly method for modification of PES membrane with enhanced antifouling and antibacterial performance.

Harnessing the power of floating photovoltaic: A global review

As the global demand for energy continues to increase, floating photovoltaic (FPV) power is gaining more attention as a promising clean energy source. This paper summarizes the unique advantages of FPV, such as its freedom from land restrictions, higher energy output, and potential integration with other forms of energy. However, FPV also faces challenges due to complex and harsh environmental conditions such as wind, waves, corrosion, and biological fouling. Therefore, the integrated mechanism design and the use of lightweight hydrophobic materials are crucial for ensuring the safety and stability of FPV systems under such conditions. This article also highlights certain key design points and optimization techniques that can improve the structural reliability of FPV systems. With continuous technological advancements and the accumulation of experience, the production efficiency of FPV has improved, leading to the expansion of FPV projects and a reduction in investment costs. As a result, the development of FPV has been accelerating globally, with numerous high-capacity projects being constructed. Building upon the previous literature reviews, this paper provides a concise review of the latest FPV case studies, innovative technologies, challenges in marine environments, economic costs, and market prospects from various perspectives. The primary objective is to encourage further research and application in the field of FPV.

Electronic and Structural Properties of Core-Shell Amino-Silica Nanoparticles: DFT And SCC-DFTB Calculation

Introduction: Silica nanoparticles (SNP) are extremely promising tools in nanotechnology and nano medicine. In most of applications such as capture and release of bacteriophage viruses the nano-structures of silica are coated by bio-compatible groups such as amine compounds. The presence of amino groups on the surface of the biosensors enables the installation of analyte receptors and antifouling agents such as oligo (ethylene oxide). Therefore, in this study, the electronic and structural properties of Core-Shell amino- Silica Nanoparticles are investigated.Material and Methods: In this investigation, we aim at obtaining the optimized structures and evaluate the geometries of the ground state for (SiO2) n (n=16, 20) nanoclusters. The electronic properties computed by density functional theory with GGA approximation and SCC-DFTB with hybrid Slater-Koster files are investigated and the effect of functionalization on such properties is discussed.Results: Solvolysis of studied structures is examined and it is shown that the highest occupied and lowest unoccupied molecular orbital states shift to obviously higher energy levels, which lead to more stable hydrogenated nanoclusters. The stability of nanoclusters rises by functionalization with amino and methylamine groups. Charge analysis of functionalized systems indicates the reactivity of nanoclusters. The results obtained in this paper are useful for chemical and biochemical applications of silica nanostructures.Conclusion: Results show that the length of amine hydrocarbon chain can control the electronic and magnetic properties of studied silica nanocluster (SNP) with different number of SiO2 unit. Pure ultra-small nanocluster shows the impressive spin splitting around the Fermi level, which is due to the spin splitting of outer silicon atoms. This feature of silica nanoclusters may be notable for applications in electronics.

Fabrication of an anti-fouling coating based on epoxy resin with a double antibacterial effect via an in situ polymerization strategy

The hull and subsea equipment are often plagued by widespread marine biofouling, so developing a sustainable environmental protection antifouling paint is urgent. The study designed and developed an antifouling composite coating system (E44-Ag-PGI) with a synergistic antibacterial effect based on the dual strategy of the bacteriostatic effect of stereochemical structure on polymer surface and release sterilization of metal nanoparticles. Firstly, an antifouling agent (PGI) was prepared by simple radical polymerization by combining glycidyl methacrylate with borneol, a complex bicyclic monoterpene structure extracted from plants. Then bisphenol A epoxy resin with strong adhesion to metal was selected as the base material. The synthetic antifouling agent with epoxy groups was polymerized in situ into the epoxy resin network, and compared with pure epoxy resin, the elongation at break of E44-Ag-PGI coating with 20 % PGI content increased from 40.37 % to 124.8 %, which was mainly attributed to the introduction of a soft chain of antifouling agent polymer, which improved the flexibility of the coating. Meanwhile, the antibacterial efficiency of the coating against Pseudomonas aeruginosa and Staphylococcus aureus was 97.69 % and 95.9 %, respectively. This excellent antibacterial performance was mainly attributed to the synergistic antibacterial action of natural borneol and AgNPs. In addition, the biofilm and diatom resistance experiments of the coating showed that the coating also has an excellent antifouling effect. This provided a new research idea for environmentally friendly antifouling coatings.

Process Study on the Preparation of Degradable Antifouling Paint Coatings by Solvent Method

Marine anti-fouling coatings have been widely used as one of the effective methods to prevent marine fouling organisms from adhering to the surfaces of various marine facilities. The main types are self-polishing anti-fouling coatings and low surface energy anti-fouling coatings, and biomimetic antifouling paint. Due to the increasing awareness of environmental protection, the anti-fouling coatings harmful to the environment have been gradually banned, so the research and development of new anti-fouling coatings has become the primary direction of development.In this paper, polycaprolactone and PLA were used as resin base materials, capsaicin as bio-friendly anti-fouling agent, starch as polysaccharide additive, the experimental samples were prepared by adjusting the mixture ratio of these materials. The experiment of adding starch and unadded starch was carried out by using Magnetic stirrer and other experimental equipment to simulate the hanging board method on the sea and observed and recorded, the effect of Starch on the hydrolysis of anti-fouling coatings using single component or blends of biodegradable materials such as polycaprolactone, polylactic acid (PLA) as resin matrix was investigated.The results showed that starch could promote the hydrolysis of resin-based materials such as PCL, and the solubility of PCL and PLA in chloroform was obtained, a preparation method of antifouling coating for marine static culture equipment was obtained.