Optimized silyl ester diblock methacrylic copolymers: A new class of binders for chemically active antifouling coatings

This work focuses on the assessment of the erosion properties and antifouling (AF) performance of silyl ester copolymer-based coatings through laboratory and field tests. Silyl ester diblock copolymers were synthesized via the reversible addition-fragmentation chain transfer polymerization and were selected as binders for developing copper-free chemically active coatings. AF coatings were subsequently prepared using biocides (Sea-Nine™ 211, Preventol^® A4S, and zinc pyrithione). Laboratory-based bioassays, targeting the growth of selected microorganisms (bacteria and microalgae) and barnacle settlement, highlighted that the silyl ester methacrylic-based binders did not inhibit the growth of microorganisms, are essentially non-toxic to nauplii and reduced the settlement of Amphibalanus amphitrite cyprids. The corresponding biocidal coatings are potent toward bacteria and diatoms but were demonstrated to be toxic against the barnacle larvae. Field test results showed variations with geographical locations: in sub-tropical area, the silyl ester methacrylic-based coatings failed to inhibit the settlement of barnacles; however, field tests performed in Mediterranean Sea for 18 months demonstrated that biocidal silyl ester methacrylic-based coatings were promising candidates.     

Seawater-soluble pigments and their potential use in self-polishing antifouling paints: simulation-based screening tool

This work concerns the on-going development of efficient and environmentally friendly antifouling paints for biofouling control on large ocean-going ships. It is illustrated how a detailed mathematical model for a self-polishing antifouling paint exposed to seawater can be used as a product engineering tool to obtain a quick estimate of the paint behaviour that a given seawater-soluble pigment will provide. In the present context, “pigment” refers to relevant particulate solids of organic-, inorganic-, or biological nature. Simulations performed at 15 and 30 °C suggest that pigment solubility and seawater diffusivity of dissolved pigment species have a significant influence on the polishing and leaching behaviour of a typical self-polishing paint system. The pigment size distribution, on the other hand, only has a minor influence on the paint–seawater interaction. Simulations also indicate that only compounds which are effective against biofouling at very low seawater concentrations are useful as active antifouling paint ingredients. The need for model verification and exploration of practical issues, subsequent a given pigment has been found of interest, is discussed. The model approach is of relevance in the search for novel antifouling paints and for the development of accelerated test methods.     

新型无毒防污涂料的发展现状

自含锡防污涂料被禁止使用以来,无毒环保型防污涂料有了很大的发展.本文综述了一些无锡自抛光防污涂料以及用有机硅改性的丙烯酸和聚氨酯涂料,并做了展望.     

Comparison of drag characteristics of self-polishing co-polymers and silicone foul release coatings: A study of wettability and surface roughness

An experimental study has been carried out to evaluate the drag characteristics of different self-polishing co-polymers (SPC) (tin based and tin-free) and a silicone foul release (FR) coating. Drag measurements have been performed on a smooth aluminum cylinder connected to a rotor device. Various coatings on cylinders were examined and differential length technique was also used to avoid the end effects during rotation. Surface energy of the coated samples was determined using static contact angle measurement. Characteristic roughness measurements of the coated surfaces were evaluated with atomic force microscopy (AFM) technique.

Drag measurements showed that the frictional resistance of the FR coated cylinders was lower than that of SPC coated samples.

Contact angle results showed that the critical surface tension and its polar component for silicone FR coating are less than SPC coatings. This prevents firm adhesion of fouling organisms on underwater hulls.

AFM studies revealed a lower surface roughness for silicone FR coating as compared to SPC coatings. Also, its surface texture is considerably different from SPC coatings.

It can be concluded that the drag characteristics of a surface are affected by its free energy and roughness parameters.     

Development and evaluation of self-polishing urethane coatings with tethered quaternary ammonium biocides

The synthesis and characterization of hydrolysable, antimicrobial cross-linked polyurethanes are described. Cross-linking of isocyanate-terminated urethane oligomers with glycol-modified silanes was used as a novel method for imparting enhanced mechanical integrity and hydrolytic potential to polyurethane coating systems. By combining these cross-linkers with a variety of biocidal quaternary ammonium salts and polyisocyanates, a library of hydrolysable polyurethanes were developed with controllable mechanical, thermal, hydrolytic, and antimicrobial properties. Up to a 3-log reduction of viable microbes was observed and correlated with the surface content of side chain quaternary ammonium salt moieties. Diminished antibacterial characteristics of completely amorphous systems are attributed to the segregation of low surface energy constituents at the material:air interface and relegation of biocidal species to within the bulk material.     

A Letter to Editor: On the use of the term “self-polishing” for antifouling paints

This letter presents a confusion on the use of the term “self-polishing” which is widely used in the antifouling paint industry and in published literature.     

Study on film forming organo-copper polymer

Film forming organo-copper polymer was synthesized from diethanol amine. The organo-copper polymer (copper salt of polyester amide) contains long chain amide in the side group. The intermediates and the final products were characterized for chemical structure, molecular weight, copper content, curing and thermal properties of cured resin. Organo-copper polymer was used as soluble resin to formulate a coating. Mechanical strength and leaching behavior of the coating were studied. The coating was found to be self-polishing in nature.     

Studies on novel silicone/phosphorus/sulphur containing nano-hybrid epoxy anticorrosive and antifouling coatings

The objective of the present work is the development and characterization of silicone, phosphorous and sulphur containing nano-coatings using diglycidyl ether of bisphenol-A type epoxy resin (DGEBA) as base material, tris (p-isocyanatophenyl) thio phosphate (DESMODUR) as modifier and POSS-NH₂ (polyhedraloligomeric silsesquioxane) as nano-reinforcement. The nano-coatings were cured by Aradur 140 (polyamidoimidazoline) and XY 54 (polyamidoamine) curatives. The corrosion and fouling resistant properties of these coatings were evaluated by potentiodynamic polarization, electrochemical impedance, salt-spray and antifouling tests. It was interesting to observe that the molecular structure of curing agents as well as the nano-reinforcing effect of POSS-NH₂ significantly influenced their corrosion and fouling protection behaviour. For example, coating system ‘1’ alone retained an impedance value of 10⁹ ohm cm² even after 30 days of immersion indicating no deterioration on the coating. However the impedance values of other specimens decreased from 10⁹ to 10⁷ and 10⁶ ohm cm². This observation clearly indicates the synergistic effect of curing agent and nano-reinforcing effect of POSS-NH₂ towards corrosion resistance. Similar observation was made from the antifouling study, with a marked inhibition of bacterial adhesion on such coated panels.     

Durable self-polishing antifouling Cu-Ti coating by a micron-scale Cu/Ti laminated microstructure design

Marine biofouling is a major issue deteriorating the service performance and lifespan of marine infrastruc-tures.The development of a durable,long-term,and environment-friendly antifouling coating is therefore of significant importance but still a critical challenge in maritime engineering.Herein,we developed a Cu-Ti composite antifouling coating with micron-sized alternating laminated-structure of Cu/Ti by plasma spraying of mechanically mixed Cu/Ti powders.The coating was designed to enable controlled release of Cu ions through galvanic dissolution of Cu laminates from the Cu/Ti micro-galvanic cell in aqueous solution.Results showed that remarkable antifouling efficiency against bacterial survival and adhesion up to ～100 ％ was achieved for the Cu-Ti coating.Cu/Ti micro-galvanic cell was in-situ formed within Cu-Ti coating and responsible for its Cu ions release.The successive dissolution of Cu laminates resulted in the formation of micro-channels under Ti laminates near surface,which contributed to controlled slow Cu ions release and self-polishing effect.Thus,environment-friendly antifouling capability and ～200 ％longer antifouling lifetime than that of the conventional organic antifouling coatings can be achieved for the Cu-Ti coating.On the other hand,as compared to the conventional organic antifouling coatings,the Cu-Ti composite coating presented much higher mechanical durability due to its strong adhesion strength,excellent mechanical properties,and two orders lower wear rate.The present laminated Cu-Ti coating exhibits combination of outstanding antifouling performance and high mechanical durability,which makes this coating very potentially candidates in marine antifouling application.