Efficient and robust coatings using poly(2-methyl-2-oxazoline) and its copolymers for marine and bacterial fouling prevention

Molecular design, fabrication, and properties of thin-film coatings based on poly(2-methyl-2-oxazoline) (PMOX) and its copolymers were investigated to tackle problem of marine and bacterial fouling prevention. The ultraviolet crosslinkable macromonomer poly(2-methyl-2-oxazoline) dimethylacrylate was synthesized by cationic ring-opening polymerization in a microwave reactor initiated by 1,4-dibromobutane. In order to study the charge effect of the PMOX coatings on the adhesion of fouling organisms, PMOX surfaces with negative, neutral, and positive ζ-potential values were prepared by copolymerization with the positively charged monomer [2-(methacryloyloxy)-ethyl]trimethylammonium chloride. The coatings were stable in sea water for at least 1 month without significant reduction in the film thickness. The marine antifouling activity was evaluated against barnacle cyprids Amphibalanus amphitrite and algae Amphora coffeaeformis. Results showed that PMOX coatings provide effective reduction of the settlement regardless of the molar mass and surface charge of the polymer. Bacterial adhesion test showed that PMOX coatings effectively reduce Staphylococcus aureus and Escherichia coli adhesion. Owing to its good stability and antifouling activity PMOX has a great potential as antifouling coating for marine antifouling applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 275–283     

Superhydrophobic polymer multilayers for the filtration- and absorption-based separation of oil/water mixtures

We report layer-by-layer approaches to the design of superhydrophobic and superoleophilic substrates for the filtration- or absorption-based separation of bulk oil from oil/water mixtures. Fabrication of covalently cross-linked, nanoporous polymer multilayers on mesh substrates yielded superhydrophobic and superoleophilic porous media that allow oil to pass, but completely prevent the passage of bulk water. This approach can be used to promote the filtration of oil/water mixtures, and these film-coated substrates can be bent and physically manipulated without affecting oil- and water-wetting properties. Fabrication on three-dimensional macroporous polymer pads yielded flexible objects that float on water and absorb oil at contaminated air/water interfaces. This approach permits oil to be recovered by squeezing or rinsing with solvent and the reuse of these materials without decreases in performance. These pads can also absorb oil from simulated seawater, brine, and other media representative of marine or industrial contexts where oil contamination can occur. Our results address issues associated with the design of polymer-based coatings for the separation, removal, and collection of oil from oil-contaminated water. With further development, this approach could provide low-energy alternatives to conventional remediation methods or yield new strategies that can be implemented in ways that are impractical using current technologies. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3127–3136     

Development of Green Waterborne UV-Curable Castor Oil-Based Urethane Acrylate Coatings: Preparation and Property Analysis

A series of novel waterborne UV-curable polyurethane dispersions were synthesized from castor oil, IPDI, DMPA, and HEMA by the acetone process. The prepared UV-PUD was mixed with three different monomers and characterized for the parameters relevant to the study by physical, spectroscopic, and chemical methods. The effect of monomer type on the physicochemical and thermal properties of UV-PUDs revealed that the number of unsaturated groups present in the monomer had a pronounced effect on physicochemical, mechanical, and thermal properties. The combination of renewable resource and environmentally compliant technology give these UV-PUDs potential scope in coating applications.     

Water‐based inorganic/polymer hybrid particles prepared via a multiple miniemulsion process

A universal method for the synthesis of water‐based inorganic–polymer hybrid particles was developed in which no organic solvent is required. To demonstrate the versatility of this process, zinc phosphate, calcium carbonate, and barium sulfate were chosen as different pigment examples which additionally can be utilized for functional coating applications. Furthermore, a complex polymeric composition based on epoxy–acrylic–styrene was chosen to illustrate the versatility from a soft matter point of view. The overall synthesis process was carried out by coemulsification of two inverse miniemulsions, containing two precursors, surrounded with a polymerizable continuous phase. This was then transferred to a direct miniemulsion by addition to a surfactant solution and subsequent homogenization followed by radical polymerization of the vinylic monomers. To our knowledge, this is the first work where a polymerizable continuous phase has been used in an inverse miniemulsion formation followed by transfer to a direct miniemulsion, followed by polymerization, so that the result is a water‐based dispersion. The resultant dispersion was characterized by dynamic light scattering; the particles were investigated via transmission electron microscopy with in situ determination of crystallinity using electron diffraction. Elemental analysis was also performed for the particles and the polymerized miniemulsions using X‐ray fluorescence and inductively coupled plasma‐optical emission spectroscopy, respectively. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Degradation of poly(butyl methacrylate) model compounds studied via high‐resolution electrospray ionization mass spectrometry

This study investigates the degradation behavior of poly(n‐butyl methacrylate) ( p(nBMA) ), poly(tert‐butyl methacrylate) ( p(tBMA) ), and poly(hexafluoro butyl methacrylate) ( p(HFBMA) ) on a molecular level under extreme environmental conditions. The polymers chosen are readily applicable in the formulation of surface coatings and were degraded under conditions which replicated the harsh Australian climate, in which surface coatings may reach temperatures of up to 95 °C and are exposed to broad‐spectrum UV radiation of up to 1 kW m^?2. The degradation profiles were mapped with high‐resolution electrospray ionization mass spectrometry (ESI‐MS) with a LCQ quadrupole ion trap mass analyzer, with the peak assignments confirmed to within 3 ppm using ESI‐MS with a LTQ‐Orbitrap mass detector. It was found that in all the butyl ester polymers analyzed herein—regardless of their tertiary side‐chain structure—the loss of the butyl ester group and subsequent formation of acid side groups are a component of the overall degradation pathway of poly(butyl methacrylate)s under these harsh conditions. However, it is also demonstrated that the magnitude of this pathway is intimately linked to the side‐chain structure with the propensity for degradation decreasing in the order p(tBMA) > p(nBMA) > p(HFBMA) . The degradation mechanisms identified in this study, in combination with the previous end‐group degradation studies of poly(methyl methacrylate) and poly(n‐butyl acrylate), have allowed a much deeper understanding of the molecular degradation behavior of poly(acrylate)s and poly(methacrylate)s in an extreme natural environment. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Adhesion,atomic structure,and bonding variation at TiN/VN interface by chemical segregation

Introduction of alloying elements often alters properties of materials. In the technologically significant multilayered superlattice coatings, interfaces are known to play a key role in the deformation mechanisms, especially in the phenomenon of interface‐induced superhardness at nanoscale. Here, we elucidate, by first‐principles calculations, atomic structure of TiN/VN interface and its relationship to adhesion upon introducing Cr, Mo, Ta, Y, Al, Nb, Zr, and Sc, the very commonly occurring alloying elements in the coating. We find that the elements Cr, Mo, Ta, Y weaken substantially interfacial adhesion, whereas the others modify adhesion only slightly. The bond length, charge transfer, and interactions between atoms at interface are found to be the key factors to understanding the origin of shift in properties in the coatings with the chemical alloying. Using several methods of analysis, we have clarified electronic mechanism behind the variation induced by alloying elements and determined the interfacial bonding nature to be mainly ionic with a certain degree of covalency. The theoretical calculations presented provide insight into the complex electronic properties of the TiN/VN interfaces with alloying elements. Our findings help enhance performances of the multilayered coatings for wide‐ranging applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Interacting nanoparticles with functional surface groups

Functionalized nanoparticles with ionizable groups have generated a large variety of structures with important potential applications in technology. The nature of their interactions is crucial to determining their solubility and to exploring assemblies with diverse symmetries. Here, we use a molecular theory to describe the interactions between two nanoparticles coated with short polymer chains that contain ionizable (functional) end‐groups immersed in aqueous salt solution. It is shown here that the fraction of ionized functional groups in the system depends on factors such as the ionic strength and pH of solution, grafting density of polymer chains, the chain length, as well as the separation distance between the nanoparticles. The interactions between two neighboring nanoparticles influence the charge regulation of the end‐groups, which consequently induces an asymmetric distribution of these charged end‐groups on the nanoparticles, and thus confers a preferred directionality in nanoparticle–nanoparticle interactions. We show that the charge regulating system is less repulsive than an equivalent system with a fixed charge distribution. This is due to a decrease in the charge density of the weak acid end‐groups, to avoid a local increase in counterion confinement (condensation) in the region between neighboring nanoparticles, when their separation decreases. The anisotropic degree of ionization found in our results can be used to design aggregates of nanoparticles with reduced symmetries. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012     

Novel marine antifouling coatings inspired by corals

Biofouling is a major problem facing the marine industry. Since toxic antifouling coatings were banned globally due to their negative impacts on the marine environment, the development of environmental-friendly and efficient antifouling coatings has been identified as a pressing need. As an alternative, the antifouling coatings inspired by corals have attracted a great deal of attention over these years. within the marine environment, corals have evolved an excellent antifouling capability. There are five major antifouling strategies applied by corals, including natural antifoulants, foul release effect, sloughing effect, soft tentacles, and fluorescence effect. In this paper, a brief review is conducted to introduce the antifouling coatings inspired by the five strategies. Moreover, a discussion is conducted about the existing problems with the five strategies and the direction of their further development is indicated.     

喷涂轨迹对铝合金表面等离子喷涂Mo/8YSZ功能梯度热障涂层温度场的影响规律研究

为了突破传统Mo/8YSZ双层热障涂层高温易剥离的技术瓶颈,研究喷涂轨迹对等离子喷涂功能梯度热障涂层温度场的影响规律,利用ANSYS有限元仿真模拟软件,基于"生死单元"的方法,建立了等离子喷涂功能梯度热障涂层的有限元模型,模型中考虑了材料的相变潜热及不同温度下的热物性参数,分析了不同喷涂轨迹下喷涂构件温度及温度梯度的分布情况。结果表明:当喷涂粘结层和过渡层材料时,采用同向的喷涂轨迹时,喷涂构件的温度最高;采用同种材料同向喷涂,异种材料喷涂方向相反的喷涂轨迹时,喷涂构件的温度次之;采用"S"型的喷涂轨迹时,喷涂构件温度最低。当喷涂陶瓷层材料时,采用"S"型的喷涂轨迹时,喷涂构件的温度最高;采用同向的喷涂轨迹时,喷涂构件的温度次之;而采用同种材料同向喷涂,异种材料喷涂方向相反的喷涂轨迹时,喷涂构件的温度最低。采用"S"型喷涂轨迹进行喷涂作业时,喷涂构件左右两端面温度分布的均匀性优于另外两种喷涂方式;采用同向的喷涂轨迹进行喷涂作业时,基体温度的波动幅度较另外两种喷涂方式小。通过设计梯度结构,并调控喷涂轨迹,可减小构件厚度方向的温度梯度,从而提升基体与涂层的结合强度。