Marine fouling organisms have caused inconvenience to humans for a long time owing to their high vitality and great destructiveness. Self-polishing antifouling coatings are considered to be among the most effective antifouling technologies. In this study, zinc-based acrylate copolymers (ZnPs) were designed and synthesized using a bifunctional zinc acrylate monomer (ZnM) as a new self-polishing monomer, and three acrylate monomers (namely, methyl methacrylate, ethyl acrylate and 2-methoxyethyl acrylate) were used as comonomers. ZnPs that contained the new ZnM were characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. Different antifouling coatings were prepared using the previously mentioned ZnPs as the matrix material, and their erosion properties were investigated using a lab rotor test. A field test of the prepared coatings at various geographical locations showed their excellent antifouling performance as they inhibited the settlement of barnacles in both the South China Sea for 9 months and in the Yellow Sea for at least 15 months. The results of this study highlight that the biocidal ZnP-based coatings are highly promising candidates for marine antifouling applications.

Development of an environmentally friendly and efficient marine antifouling coating is a central goal in marine antifouling. In this study, a series of novel hybrid zinc/silyl acrylate copolymers (Zn/Si-acrylate copolymers) composed of tri(isopropyl)silyl acrylate (TIPSA), zinc-2-ethylhexanoate methacrylate (Zn-monomer), ethyl acrylate and methyl methacrylate were synthesized and their surface compositions, thermal degradation and hydrolysis properties were investigated. After being immersed in seawater, the hydrolysis of TIPSA and Zn-monomer could lead to a gradual self-peeling of the Zn/Si-acrylate surfaces, which was controlled by the ratio of TIPSA to Zn-monomer. The Zn/Si-acrylate copolymers with high Zn-monomer content showed excellent performance in the resistance of diatom Phaeodactylum tricornutum (P. tricornutum) growth on the Zn/Si-acrylate films. Both the self-peeling and release of zinc compounds lead to antifouling properties, which demonstrated that Zn/Si-acrylate copolymers were an effective resin for marine antifouling in static or low flow conditions.

Isocyanate-based polyimide foams (PIFs) with different dosages of liquid tri (1-chloro-2-propyl) phosphate (TCPP) and micro-sized hydrotalcites (LDHs) particles alone, as well as different mixing ratios of TCPP and LDHs, were prepared via a one-step process in this work. Limiting oxygen index (LOI) and cone calorimeter test (CCT) results indicated that TCPP exhibited more pronounced flame retardant efficiency than LDHs for isocyanate-based PIFs. However, scanning electron microscopy images and digital macrostructural images results showed that, in contrast to LDHs, when the dosage of TCPP exceeded 10% it caused a clear cracking effects on the macro-cellular structure and opening cell effects on the micro-cellular structure for isocyanate-based PIFs. Because the dramatically volatilization of TCPP during the postcuring process caused obvious cellular contraction in the isocyanate-based PIFs. Meanwhile, the use of TCPP also obviously decreased the thermal stability of isocyanate-based PIFs unlike LDHs. However, when these two flame retardants were used in combination, they could effectively enhance the fire resistance and ensure macro- and micro-cellular structures of the isocyanate-based PIFs, unlike standalone use of TCPP and LDHs. When 10% TCPP was simultaneously used with 10% LDHs, the macro- and micro-cellular structures of the resultant foams were clearly improved compared with foams prepared using TCPP only. These results were believed to be attributable to LDHs dispersion in the foams, which enhanced the strength of cellular windows and skeletons, then restrained the cell contraction. Compared with foams without flame retardants, the fire resistance of the isocyanate-based PIFs prepared with 10% TCPP and 10% LDHs was obviously enhanced; specially, the LOI was enhanced by 29.4%, and the peak of heat release rate (PHRR) decreased by 36.1%. Thus, the use of liquid and solid flame retardants in combination may effectively yield isocyanate-based PIFs with high quality cellular structures and excellent fire resistance.

A novel single-step approach was developed to prepare large-scale MgAl–LDHs ultrathin nanosheets. The key point of the successful realization was that we employed a high concentration of H2O2. Oxygen molecules, derived from in situ decomposition of H2O2, were speculated to be the decisive factor leading to complete separation of LDHs layers. The ultrathin nanosheets were characterized by XRD, TEM, AFM, FT-IR, and TG–DSC. The results indicated that the thickness of these nanosheets was about 1.44 nm, which was almost in perfect agreement with the theoretical thickness of two LDHs layers. From the TG–DSC curves, the weight loss of these exfoliated MgAl–LDHs ultrathin nanosheets at 500 °C was 18.5%, which was much smaller compared to the 32.3% weight loss of unexfoliated MgAl–LDHs.Graphical abstractHighlights► A novel single-step approach is developed to prepare MgAl–LDHs ultrathin nanosheets. ► Large-scale MgAl–LDHs nanosheets with thickness of about 1.44 nm are obtained. ► The weight loss of these nanosheets at 500 °C is very low.