Photo‐curable highly water‐repellent nanocomposite coatings

Modification and use of natural products have gained a lot of interest in recent years due to their environmental friendliness and their availability from different sources. In this study, (castor oil)‐based photo‐curable highly hydrophobic coatings were prepared and characterized. Castor oil was first modified with 3‐isocyanatopropyltriethoxysilane and then hydrolyzed prior to the coating preparation. The resulting precursor was mixed with norbornyl acrylate and hexanediol diacrylate, and highly roughened hydrophobic coatings were prepared with the aid of fluorinated/nonfluorinated alkoxysilane coupling agents and hydrophobic fumed nanosilica particles. The coatings were applied on borofloat glass. The addition of fluorine and nanosilica showed a significant impact on the properties of the coatings. As the fluorine and nanosilica contents were increased in the formulations, flame retardancy and the contact angle values of the coatings increased. The surface roughness of the coatings increased with the addition of hydrophobic fumed nanosilica particles. Also, the relation between the surface energy and the contact angle values of the coatings was investigated. J. VINYL ADDIT. TECHNOL., 19:31–38, 2013. © 2013 Society of Plastics Engineers     

氟化丙烯酸/二氧化硅杂化超疏水涂层的性能研究

在醇溶性氟化聚合物溶液中,首先在水量不足的酸性条件下,掺杂聚四氟乙烯(PTFE),得到了均匀的复合溶胶。涂敷后,经表面凝胶化技术处理,使涂层表面得到微米和纳米相结合的阶层结构。TEM和XPS证实了凝胶化只在涂层表面发生,SEM观察到涂层表面的形貌与天然荷叶表面极其相似,该方法制备的涂层具有良好的力学性能,可用于制备超疏水性功能涂层材料。     

Synthesis of UV-curable polysiloxanes containing methacryloxy/fluorinated side groups and the performances of their cured composite coatings

Three novel UV-curable polysiloxanes consisting of polysiloxane backbone with methacryloxy/fluorinated side groups were synthesized, and their structures were characterized by FT-IR, ¹H NMR and ¹³C NMR. A series of UV-cured composite coatings based on the synthesized polysiloxanes and an epoxy methacrylate were obtained through photopolymerization. Their gel content, flexibility, hardness, gloss, contact angle, thermal behavior as well as water absorption ratio were investigated. Results found that the siloxane component could enhance the flexibility and gloss of coatings, while the presence of fluorinated groups could improve the hardness. The combination of silicon and fluorine in the same polymer could increase thermal stability and water resistance of the coatings and decrease their surface energy simultaneously. The observation of the fractured-surface morphology showed that the polysiloxanes could be well dispersed in the epoxy methacrylate to some extent. A suitable addition of such polysiloxane in photocurable coating matrixes may provide excellent properties for the cured coatings and widen their applications.     

Reactions of copper ions with amines in the presence of self‐assembled fluorinated oligomeric aggregates

Copper acetylacetonate reacted with N,N‐diethylmethylamine and 4,4′‐thiobis(6‐t‐butyl‐o‐cresol) in the presence of self‐assembled fluorinated oligmeric aggregates formed by fluoroalkyl end‐capped 2‐[3‐(2H‐benzotriazol‐2‐yl)‐4‐hydroxyphenyl]ethyl methacrylate–N,N‐dimethylacrylamide cooligomer [R_F–(BTRI)_x–(DMAA)_y–R_F; R_F = CF(CF₃)OCF₂CF(CF₃)OC₃F₇] to afford stable fluorinated aggregates–copper ions nanocomposites. These fluorinated oligomeric aggregates–copper ions nanocomposites thus obtained were applied to the dispersion of copper ions nanocomposites above the traditional organic polymeric materials such as poly(methyl methacrylate) (PMMA) surface. On the other hand, copper (II) chloride reacted with hydrazine hydrate in the presence of fluorinated oligomeric aggregates formed by fluoroalkyl end‐capped N,N‐dimethylacrylamide homooligomer to afford stable copper nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1328–1334, 2006     

Compositional effects on the fouling resistance of fluorourethane coatings

Conclusions  A series of fluorinated polyurethane polymers have been prepared and characterized. Immersion experiments have been performed to determine the fouling-release effectiveness of the coatings. The surface energies of the films are between 12 mJ m⁻² to 33 mJ m⁻² and are controlled by the fluorine content of the polymer. These surface energies are well below the values shown by conventional alkyd, epoxy, vinyl, polyester, and polyurethane coatings (39 mJ m⁻² and 50 mJ m⁻²). Surface energy is not the dominant factor in determining the fouling- release behaviour of these coatings. Instead, measurements of the coating modulus, hardness, and glass transition temperature indicate that supple, soft polymers, with a high degree of mobility may display more effective fouling-release characteristics than more rigid, harder polymers below their glass transition temperatures. Surface roughness also appears to be a major factor in determining coating fouling-release behaviour. This work has demonstrated that marine organisms bind to fluorinated polyurethanes with significantly less strength than to the unfluorinated epoxy, vinyl and urethane resins which are now used with toxicants in marine coatings. However, this work has shown that these fluorinated polyurethanes are not sufficiently promising to merit further attention as non-toxic anti-fouling coatings for ship hulls. Fluorinated polyurethanes remain very attractive coatings for exterior and anti-corrosive service, especially in application requiring easy cleanability and resistance to sunlight, weather, and chemicals.     

Fluorinated acrylic polymers: Surface properties and XPS investigations

A series of polymers based on methylmethacrylate, butylacrylate, and ω‐perfluorooctylalkylacrylate were prepared by radical polymerization. By changing both the length of the hydrocarbon spacer, between the fluorinated chain and the ester function of the fluorinated monomer, and its concentration, the surface properties of the resulting terpolymers were greatly influenced. Polymers containing small amounts of fluorinated comonomer units had considerably reduced surface energies compared to the copolymer poly (methylmethacrylate‐co‐butylacrylate) taken as reference. The outermost surface composition has been investigated by the XPS technique, confirming the strong fluorine enrichment. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 821–827, 2006     

Ultrathin perfluoropolyether coatings for silicon wafers: a XPS study

Oxidized silicon wafers were functionalized in mild conditions using alkoxysilanes containing perfluoropolyether chains: the reaction was monitored by FTIR and very thin fluorinated films were formed. After the treatment, the surface tension of the wafers decreased dramatically (from 43 mN/m for the neat wafer to 21–13 mN/m depending on the conditions of the silanization process), high repellency toward polar and apolar media was achieved. The composition of the fluorinated coatings was investigated in details by XPS spectroscopy.     

Anti-fingerprints fluorinated coating for anodized titanium avoiding color alteration

In this study amorphous fluorinated coatings applied to anodized titanium surface have been investigated. A copolymer between tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (AD60) and two perfluoropolyether containing ammonium phosphate (F10) or triethoxysilane (S10) functionalities have been tested. To estimate the color alteration of the anodized titanium surfaces due to the application of the coatings, spectrophotometric analyses have been made. Water and n-dodecane contact angles as well as apparent surface energy have been evaluated. Ellipsometry and atomic force microscopy data have been used to measure the thickness of the fluorinated coatings. A tailored mechanical preliminary test has also been explored to evaluate the adhesion of the coatings on the anodized titanium surface. The resistance to surface soiling with castor oil was also preliminarily investigated. The fluorinated coating tested on anodized titanium showed a low apparent surface energy and high chromatic aspect conservation, this is particularly evident for the titanium anodized coated with triethoxysilane functionalities fluoropolymers S10.     

Fluorinated epoxides as surface modifying agents of UV‐curable systems

Two commercially available epoxy‐fluorinated monomers, 3‐(perfluorooctyl)‐1,2‐propenoxide and 3‐(1H, 1H, 9H‐hexadecafluorononyloxyl)‐1,2 propenoxide, were used as modifying additives for UV curable systems. These two fluorinated monomers were mixed, in small amounts (less than 1% w/w) with a hydrogenated epoxy monomer 1,4‐cyclohexanedimethanol‐diglycidyl ether. The mixtures were coated on glass substrate and UV‐cured, giving rise to transparent films. Notwithstanding their very low concentrations, the fluorinated monomers caused a change in the surface properties of the films, without changing their curing conditions and their bulk properties. The air side of the coatings became highly hydrophobic, while the substrate side was unmodified. As shown by XPS measurements, the fluorinated monomers were able to concentrate selectively on the air side of the films, forming a fluorinated layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1524–1529, 2003     

Synthesis and application properties of fluorinated aromatic copolymers

Aromatic monomers with different fluorine concentrations and structural distribution patterns were synthesized. A series of copolymers based on methyl methacrylate, acrylate, and perfluorooctylalkyl acrylate were prepared by emulsion polymerization and were subsequently used as functional coatings to prepare water‐ and oil‐repellent cotton fabrics. The composition and structure of the outmost layer of the treated cotton surface were analyzed. A strong surface segregation of fluorinated segments was found for the treated samples, as shown by X‐ray photoelectron spectroscopy analysis. The basis for an in‐depth appreciation of the relationship between the molecular structure of the monomers and the properties of corresponding copolymer‐treated materials was provided (especially with regarding to their hydrophobic and oleophobic properties). The wetting characteristics of the fluorinated copolymers were found to be dependent on the density (number of side chains per constitutional repeat unit) and regularity of the fluorinated side chains. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4410–4418, 2013     

High performance UV-cured coatings for wood protection

UV-curable systems based on the copolymerisation of a typical acrylic resin with a low amount of a fluorinated monomer (<1%, w/w) were used for the protection of wood panels. In the presence of the additives, the bulk properties and the adhesion of the acrylic films were unchanged, while a strong modification of the surface was obtained. The quality aspects and the chemical resistance of the coatings applied to the wood panels were also enhanced.     

Nano‐structured materials with low surface energies formed by polyelectrolytes and fluorinated amphiphiles (PEFA)

Polymer complexes formed by polyelectrolytes and fluorinated amphiphiles (PEFA) represent a new class of materials which can be prepared easily as nano‐structured coatings on a large number of chemically different substrates. The surface energies of PEFA coatings are remarkably low and can be adjusted in the range 6–18 m Jm⁻². Many of their physical properties, such as elastic modulus and mechanical strength, are determined by the nature of the polymer structure. By adjusting charge densities, molecular weights and the content of nonionic comonomers, a great variety of optimizations for a number of applications are possible. The amphiphiles have a decisive influence on the nano‐structure and on the surface energy of these materials. They act as building blocks, which vary in their number of fluorinated chains, their chain lengths and in the ionic head‐groups. Carboxylate, phosphate and sulfonate groups are preferred for the preparation of PEFAs. The scope of this review is to present a discussion of the mesomorphous structures (from columnar discotic to perforated lamellar), the low surface energies and attractive applications of these PEFA materials. Applications are found predominantly in low‐friction and anti‐soiling coatings. © 2000 Society of Chemical Industry     

Superhydrophobic films of UV‐curable fluorinated epoxy acrylate resins

Photopolymerization processes are often used in industrial applications because of their solvent‐free formulations and various advantages over conventional thermal processes. Fluorinated monomers and oligomers yield coatings of great interest because of the peculiar characteristics of fluorine atoms: these coatings show hydrophobicity, chemical stability, weathering resistance, etc. Novel UV‐curable fluorinated epoxy acrylate oligomers were synthesized from 1H,1H‐perfluorohexan‐1‐ol, 1,6‐hexamethylene diisocyanate (HDI) and epoxy acrylate (EA). The HDI plays the role of a spacer group in the side chain between the EA backbone chain and the fluorinated segment. This new spacer containing a urethane moiety with long alkyl groups can exhibit a self‐organization effect through the formation of strong hydrogen bonding. This resulted in a stiffening of the whole HDI urethane–perfluoalkyl chain to form nanostructure surface segregation. The designed fluorinated EA with fluoroalkyl (C₅F₁₁) units in the side chain exhibited a contact angle of about 151°, which is in the superhydrophobic range. Copyright © 2010 Society of Chemical Industry     

Electrical behavior of PET films coated with nanostructured organic–inorganic hybrids

Hybrid coatings, based on poly(ethylene oxide) (PEO) or polycaprolactone (PCL) and silica (SiO₂), at different organic–inorganic compositions have been used to coat PET films employed in the electric industry to produce capacitors. The overall electrical behavior of the coated films has been investigated. The electrical strength of the coated films increases up to 10–15% of the uncoated ones regardless of polymer type (PEO/PCL) and amount of inorganic phase, as far as the thickness of the coating is below 5 μm. A systematic increase of surface electrical conductivity is found in all coated samples which however still behave as insulators. Permittivity and loss factor also increase particularly at low frequencies (< 10 Hz) on account of the presence of ions deriving from the sol–gel process and on the presence of interfacial polarization probably related to the coatings nanostructurated morphology which leads to phase separation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4870–4877, 2006     

Fluorinated polyphosphazene polyelectrolytes

Polyphosphazene polyelectrolytes containing various amounts of hydrophobic fluorinated moieties and ionic carboxylic acid groups were synthesized. Polymer compositions and molecular weights were characterized by NMR and gel permeation chromatography. Interestingly, poly[(carboxylatophenoxy)(trifluoroethoxy)phosphazene] containing 60 mol % fluorinated groups was found to be soluble in aqueous solutions. The behavior of fluorinated polyelectrolytes in reactions of ionic complexation with multivalent and monovalent salts was studied in aqueous solutions and ethanol–water mixtures. Such reactions led to the formation of ionotropic hydrogels under mild conditions and, thus, are of importance to the development of microencapsulation processes and controlled release formulations. All of the synthesized polymers underwent phase separation in the presence of multivalent ionic crosslinkers, such as spermine and calcium chloride. This included a water‐soluble polyelectrolyte containing 40 mol % ionic groups and hydrophobic polymer with only 3 mol % carboxylic acid groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 53–58, 2007     

Antireflective coatings using organically modified silica and polyimide via solution casting method

Antireflective (AR) coatings were prepared using a polyimide and two types of organically modified silica colloids via a solution casting method. The optically transparent polyimide was prepared from 2,2′‐Bis[4‐(3,4‐dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and 4,4′‐oxydianiline (ODA). The silica colloids were driven to the coating‐air interface by either the fluorinated alkyl group or PDMS (Polydimethylsiloxane) segment tethered onto the silica colloids. The amount of fluorinated alkyl groups and the molecular weight of the siloxane grafted on the silica colloid were varied. The PDMS‐silica and fluorosilica colloids were characterized by TEM (Transmission Electron Microscopy), DLS (Dynamic Light Scattering), FTIR (Fourier Transform Infrared Spectroscopy), solid‐state ¹³C NMR (Nuclear Magnetic Resonance) and solid‐state ²⁹Si NMR. The AR coatings were characterized by UV–vis (Ultraviolet–Visible Spectroscopy) transmittance spectra, AFM (Atomic Force Microscope), and SEM (Scanning Electron Microscope). The effects of modified silica loading and type of solvent on AR properties were studied. An enhancement in AR activity was observed for 1 wt% PDMS‐modified (low molecular weight) silica coatings and 3 wt.% fluorosilica‐10 in dimethylacetamide (DMAc). In comparison with cyclopentanone (CPT), DMAc favors migration of silica particles toward coating‐air interface giving higher transmittance. The migration of particles to the surface and consequently increased surface roughness was observed by SEM. POLYM. ENG. SCI., 53:2228–2241, 2013. © 2013 Society of Plastics Engineers     

含氟丙烯酸酯共聚物的合成及其涂膜表面疏水、疏油性能研究

以单体甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸、含氟(甲基)丙烯酸酯为原料,通过改变氟碳链长度、氟单体含量以及添加方式等因素,合成了一系列的含氟丙烯酸酯共聚物。利用表面接触角测试仪、红外光谱仪和多功能光电子能谱仪表征了共聚物涂膜的表面疏水、疏油性能以及表面化学成分,探讨了其影响因素。结果表明,共聚物涂膜表面疏水、疏油性能与其表面化学成分密切相关;使用长氟碳链的氟单体、增加氟单体用量以及采用在反应后期一次性加入氟单体的方法均有利于提高涂膜表面的疏水、疏油性能;当全氟辛基乙基甲基丙烯酸酯的质量分数为25%时,所得涂膜表面的氟元素质量分数达到44.284%,对水、对正十六烷的接触角分别达到127°和65°。     

Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings

UV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006     

Properties of films obtained by UV-curing 4,4'-hexafluoroisopropylidenediphenoldihydroxyethylether diacrylate and its mixtures with the hydrogenated homologue

A new ultraviolet (UV)-curable acrylic monomer, 4,4'-hexafluoroisopropylidene-diphenoldihydroxyethylether diacrylate, was synthesized: it was cured as a film and its properties compared with those of its fully hydrogenated homologue. The introduction of two CF₃groups into the monomer did not change its reactivity in the UV-curing reaction, but increased the glass transition temperature (T_g) of the cured polymeric film, decreased its refractive index (n), and lowered its surface tension. The fluorinated and the hydrogenated monomers were completely miscible and give homogeneous films: the T_g and n values were found linearly dependent on the fluorinated monomer content. The surface properties were deeply influenced by the presence of fluorine; a surface enrichment of the fluorinated monomer was evidenced by X-ray photoelectron spectroscopy analyses on the surfaces of the films obtained from mixtures of the two monomers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 979–983, 1997     

Fabrication and properties of polysilsesquioxane-based trilayer core–shell structure latex coatings with fluorinated polyacrylate and silica nanocomposite as the shell layer

Polysilsesquioxanes (PSQ)-based core–shell fluorinated polyacrylate/silica hybrid latex coatings were synthesized with PSQ latex particles as the seeds, and methyl methacrylate, butyl acrylate, 3-(trimethoxysilyl) propyl methacrylate (MPS)-modified SiO₂ nanoparticles (NPs), 1H,1H,2H,2H-perfluorooctyl methacrylate (PFOMA) as the shell monomers by emulsifier-free miniemulsion polymerization. The results of Fourier transform IR spectroscopy, transmission electron microscopy, and dynamic light scattering suggested the obtained hybrid particles emerged with trilayer core–shell pattern. Contact angle analysis, x-ray photoelectron spectroscopy, and atom force microscopy results indicated that the hybrid film containing SiO₂ NPs showed higher hydrophobicity, lower surface free energy and water absorption, in comparison with the control system (without SiO₂ NPs). Compared with the control system, the hybrid latex film containing SiO₂ NPs in the fluorinated polyacrylate shell layer showed the higher content of fluorine atoms and a rougher morphology on the film surface. Additionally, thermogravimetric analysis demonstrated the enhanced thermostability of PSQ-based nanosilica composite fluorinated polyacrylate latex film.