Film-air Interface Research Articles

Comparison of Approaches to Prepare Polysiloxane-Functionalized Acrylic Latexes

Three methods were used to prepare polysiloxane-functionalized acrylic latexes via emulsion polymerization. Ethyl acrylate and 2-ethylhexyl acrylate were used in all three methods as the acrylic phase. In the first method, an acrylic core was prepared with addition of a coupling agent, 3-(trimethoxysilyl) propyl methacrylate, after which a cyclic siloxane monomer (octamethylcyclotetrasiloxane) was reacted with the coupling agent. In the second method, a silane-terminated polysiloxane (H-PDMS) was reacted with ethylene glycol dimethacrylate, and then copolymerized with ethyl acrylate and 2-ethylhexyl acrylate in a batch emulsion polymerization. In the third method, cyclic siloxane monomer was added during emulsion polymerization of ethyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl methacrylate. Particle size distribution and particle morphology were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. A core-shell morphology was observed in TEM for the first preparation method as proposed. After film formation, surface tension, morphology and dynamic mechanical properties were investigated. Stratification was also examined by Fourier-transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX). Microphase separation was observed by atomic force microscopy (AFM) after polysiloxane modification. Energy dispersive X-ray data indicated that only the second preparation method had a higher silicon content at the film-air interface than film-substrate interface. In all methods, the storage modulus and surface energy of latex films decreased after polysiloxane modification.

Influence of electric field on laser damage properties of DLC films by unbalanced magnetron sputtering

DLC films with different thicknesses were prepared on Si substrates by the unbalanced magnetron sputtering (UBMS) method using the same experimental parameters to investigate the relationship between electric field intensity distribution and laser damage properties of the samples. The results indicated that different electric field intensity distributions in the films cause diverse laser damage properties. For the DLC films with optical thicknesses of 287, 341, 421 and 545.9nm, the electric field intensity (normalized electric field intensity squared) at the film–air interface is 0.9407, 0.7709, 0.4298 and 0.2241 respectively when at the wavelength of 1064nm. Under the same high-energy laser irradiation, the size of cracked spots of the film with a lower electric filed intensity is smaller than that with higher electric field intensity. The laser-induced damage threshold (LIDT) of the DLC samples is 0.6, 0.8, 1.2 and 1.5J/cm2 respectively (1064nm, 10ns). This shows that a higher LIDT may be obtained provided the films have lower electric field intensity at the film–air interface. Therefore, the laser damage-resistance ability of the films can be improved by optimizing the electric field to one with lower intensity during the process of film stack design and materials matching.

Separation of interface and volume absorption in HfO2 single layers

Based on the standing-wave theory, a modified method is proposed to separate interface and volume absorption in HfO 2 single layers. HfO 2 single layers with multiple half-wave optical thickness were prepared; in such case, the electric field at air-film and film-substrate interface is equal, and total absorption from both interfaces can be easily expressed by the product of electric field intensity and a simplified total interface absorption coefficient. Ultralow-absorptive substrates were used to eliminate the contribution of substrate absorption. When HfO 2 single layer was irradiated from the coated and uncoated side in the photothermal measurement, two equations were obtained and utilized to separate the interface and volume absorption. The validity of our method was further confirmed using another thickness changing approach. By contrast, irradiation direction changing method is better because only one sample is required.

Fabrication of superhydrophobic fabric coating using microphase‐separated dodecafluoroheptyl‐containing polyacrylate and nanosilica

AbstractSuperhydrophobic coating was developed on cotton fabric in this article using a dodecafluoroheptyl‐containing polyacrylate (DFPA) and nanosilica. Film morphology of DFPA on cotton fibers/fabrics and chemical compositions of the treated cotton fabric were investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and X‐ray photoelectron spectroscopy (XPS), respectively. DFPA could form a relatively even film on the cotton fabric/fiber under SEM observation; however, it presented a rough and microphase‐separated pattern under AFM observation. There were many mountain‐like protuberances. The height of the protuberances and the root mean square roughness (Rms) of the film reached about 20–50 nm and 12.511 nm in 2 × 2‐μm2 scanning field (as the scale data was 100 nm). XPS analysis indicated that the perfluoroalkyl groups had the tendency to enrich at the film–air interface. DFPA could make the treated cotton fabric with a water contact angle (WCA) at about 138.5°. Cotton fabric was previously roughened using a 1 wt % silica sol with an average particle size of 20–30 nm and then finished by DFPA; hydrophobicity of the resultant cotton fabric was strongly improved, and WCA could reach 153.6°. The color of this superhydrophobic fabric would not be influenced, but its softness decreased compared to untreated fabric. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Optimization and comparison of polysiloxane acrylic hybrid latex synthesis methods

Two methods were used to prepare polysiloxane-functionalized acrylic latexes via emulsion polymerization. Ethyl acrylate and 2-ethylhexyl acrylate were used in both methods as acrylic phase. In the first method, an acrylic core was prepared with addition of a coupling agent, 3-(trimethoxysilyl) propyl methacrylate, after which cyclic siloxane monomer (octamethylcyclotetrasiloxane) was reacted with the coupling agent. In the second method, a silane-terminated polysiloxane (H-PDMS) was reacted with ethylene glycol dimethacrylate, and then copolymerized with ethyl acrylate and 2-ethylhexyl acrylate in a batch emulsion polymerization. Particle size distribution and particle morphology were evaluated by using dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. Core-shell morphology was observed in TEM for the first preparation method as proposed. After film formation, surface tension, morphology and dynamic mechanical properties were investigated. Stratification of polysiloxane was examined by Fourier-transform infrared spectroscopy (FT-IR) and energy dispersive X-ray (EDX). Energy dispersive X-ray data indicated that only the second preparation method had higher silicon content at film-air interface than film-substrate interface. In both methods, storage modulus and surface energy of latex films decreased after grafting polysiloxane.

UV-LED 경화형 칼라 코팅의 경화특성 연구

본 연구는 UV-LED 경화형 칼라코팅에 대한 경화특성에 관한 것으로, 특히 UV-LED 파장(365, 395, 405 nm), 불활성 기체, 증감제 및 Dual curing에 따른 경화성을 평가하였다. 광경화 과정과 코팅 도막의 Film-air (FA) interface와 Film-substrate (FS) interface에서 존재하는 미반응 아크릴레이트에 대한 평가는 Photo-DSC와 FT-IR/ATR을 이용하여 각각 조사하였다. Photo-DSC 측정 결과 발열량과 전환율은 405 nm UV-LED를 이용한 코팅 시스템의 경우가 395 및 365 nm UV-LED를 사용한 경우보다 높게 나타났다. UV-LED 경화형 시스템은 전반적으로 Film-substrate (FS) interface의 경화도가 높은 것으로 나타나 후막경화가 우수함을 알 수 있었으나, Film-air (FA) interface의 표면 경화도는 산소저해 현상으로 인해 매우 낮음을 FT-IR/ATR 결과를 통해 확인하였다. 이러한 낮은 표면 경화도는 불활성 기체인 질소를 사용하거나 Dual curing 방법을 도입함으로써 개선할 수 있었다. In this study, we investigated the curing properties of UV-LED curable color coating. Specially, the effects of UV-LED wavelength (365, 395, and 405 nm), inert gas, the concentration of photosensitizer, and dual curing on the curing behavior of UV-LED coating systems were studied. The photopolymerization behaviors and the unreacted acrylate groups at Film-air (FA) interface and Film-substrate (FS) interface were investigated by photo differential scanning calorimetry (Photo-DSC) and Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR), respectively. Photo-DSC results showed that the heat flow and the ultimate conversion for coating system cured by 405 nm UV-LED were higher than the corresponding values for coating systems cured by 395 and 365 nm UV-LED. FT-IR/ATR results showed that the UV-LED curing systems improved interior and through curing of the coating film, but significantly are affected by oxygen inhibition at FA-interface. The inert environment such as nitrogen purging and the dual curing improved the surface and interior curing of the coating films.

Synthesis and surface properties of semi-interpenetrating fluorine-containing polyacrylate and epoxy resin networks

Semi-interpenetrating polymer networks (Semi-IPNs) based on fluorine-containing polyacrylate and epoxy resin were synthesized by the simultaneous polymerization of fluorine-containing acrylate and epoxy resin. Fourier transform infrared (FTIR) spectrometry and X-ray photoelectron spectroscopy (XPS) analyses proved that the fluorine-containing groups have been introduced into Semi-IPNs successfully. In addition, XPS analysis intuitively showed that the fluorine content of the film-air interface of the interpenetrating fluorine-containing polyacrylate and epoxy resin networks (FPAER-SIPNs) film was much higher than that of the film-glass interface. It is noted that the introduction of fluorine-containing groups significantly improved the hydrophobic property of polymer networks. Moreover, when the fluorine content increased, the contact angle of water on FPAER-SIPNs film was increased obviously and the water uptake was decreased gradually. These results indicated that introducing fluorine-containing groups to SIPNs has potential advantage for improving the surface properties of epoxy resin.

Synthesis and characterization of emulsifier-free trilayer core–shell polysilsesquioxane/polyacrylate/poly(fluorinated acrylate) hybrid latex particles

The trilayer core–shell polysilsesquioxane/polyacrylate/poly(fluorinated acrylate) (PSQ/PA/PFA) hybrid latex particles are successfully prepared, using functional PSQ latex particles with reactive methacryloxypropyl groups synthesized by the hydrolysis and polycondensation of (3-methacryloxypropyl)trimethoxysilane in the presence of a reactive emulsifier as seeds. Transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) confirm that the resultant hybrid latex particles have evident trilayer core–shell structure and a narrow size distribution. The Fourier transform infrared (FTIR) spectra show that fluorinated acrylate monomers are effectively involved in the emulsion copolymerization and formed the fluorine-containing hybrid latex particles. XPS analysis of the obtained hybrid latex film reveals that the intensity of fluorine signal in the film–air interface is higher than that in the film–glass interface. In addition, compared with pure polyacrylate latex film, the obtained fluorine-containing hybrid film shows higher hydrophobicity and thermal stability, and lower surface free energy.

Effect of annealing on self-organized gradient film obtained from poly(3-[tris(trimethylsilyloxy)silyl] propyl methacrylate-co-methyl methacrylate)/poly(methyl methacrylate-co-n-butyl acrylate) blend latexes

The effect of annealing on the self-organized morphology and component gradient distribution of films prepared from bimodal latexes blend containing 1:1 silicon-containing acrylate copolymer/silicon-free acrylate copolymer blend was studied using attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, scanning electron microscopy with X-ray energy-dispersive (SEM-EDX) spectrometry, and atomic force microscopy (AFM). The distribution of silicon through the whole thickness of the film as a function of annealing was investigated using confocal Raman spectroscopy (CRS). AFM results show that poly(methyl methacrylate-co-n-butyl acrylate) latex fuses to form a continuous film at 25 °C. The wettability of the acrylate components and the heterogeneous composition of poly(3-[tris(trimethylsilyloxy)silyl] propyl methacrylate-co-methyl methacrylate) result in a graded block film. ATR-FTIR and SEM-EDX measurements reveal silicon-containing components segregate at the film–air interface upon annealing. CRS further shows that the nonlinear model gradient distribution of silicon is obtained, where the content of silicon component is enhanced and it gradually varies in the bulk. When the annealing temperature increases to 120 and 180 °C, blend latexes films demonstrate varying topography and phase images, indicating phase separation is induced by annealing. Furthermore, CRS implies that the destruction of the gradient structure is attributed to the phase separation of the two blend components.

Synthesis of Self-Stratifying Polyacrylate Latex Containing Silicon

Self-stratifying polyacrylate latex containing silicon was synthesized via semi-continuous emulsion polymerization, using organic silicon and acrylate as raw materials. Transmission electron microscope(TEM) characterization indicated that the particles were form uniform analogous core-shell structure and dynamic light scattering(DLS) analysis possessed narrow size distributions. The results of X-ray photoelectron spectroscopy(XPS) proved the propensity of silicon enrichment at film-air interface, which revealed self-stratifying phenomenon. The thermal stability of the latex films determined by thermogravimetric analysis(TGA) was increased 24 °C as the join of organic silicon.

Synthesis and surface activity of high and low surface energy multi-end functional polybutadiene additives

We report here the synthesis of well-defined, polybutadiene additives; chain-end functionalised with either multiple fluorocarbon or hydroxyl groups. Additives containing low surface energy fluorocarbon groups were made by end-capping polybutadienyllithium prepared via living anionic polymerisation while a combination of living anionic polymerisation and “click chemistry” was used to make high surface energy, hydroxyl functionalised additives. These synthetic methodologies resulted in a high degree of chain-end functionalisation as determined by 1H-NMR. The functionalised polybutadiene samples were then blended in low concentration with well-defined (unfunctionalised) perdeuterated polybutadiene to establish their effectiveness as surface modifying polymer additives. Elastic recoil detection analysis (ERDA) revealed that the functional polybutadiene additives were very surface active in spin-cast blended films on silicon substrates. The hydroxyl functionalised polymer segregated strongly to the polymer–silicon oxide interface, whereas the fluorocarbon functionalised additives were found to be in excess at the air interface of the polymer film. The wettability of pure additives on the surface of a silicon wafer and Teflon™ were also determined by static contact angle measurement. We anticipate that these additives could be utilised to disperse and stabilise nanoparticles in nanocomposites, and enhance the adhesion of polybutadiene onto low and high energy surfaces. Investigations into the application of the described additives are ongoing and will be reported at a future date.

Synthesis and Characterization of Polyacrylate Latex Containing Fluorine and Silicon

Polyacrylate latex containing fluorine and silicon was successfully synthesized by semi-continuous seed emulsion polymerization, using organic silicon(OSi) monomer, fluorocarbon(FC), methacrylic acid(MAA), and butyl acrylate(BA) as raw materials. Transmission electron microscope(TEM) characterization indicated that the latex particles were form uniform analogous core-shell structure. Dynamic light scattering(DLS) show a narrow size distribution. The results of X-ray photoelectron spectroscopy(XPS) revealed the fluorine and silicon transfer to the film-air interface. The reaction was evaluated using fourier transform infrared(FT-IR) spectrum. The thermal stability of the latex films which analysed by thermogravimetric(TG) was improved due to the join of OSi and FC.

Structure and surface properties of fluorinated organic–inorganic hybrid films

Fluorinated organic–inorganic hybrid films were prepared by sol–gel process from tridecafluoroctyltriethoxysilane (PFAS), 3-glycidoxypropyltrimethoxysilane, and tetraethoxysilane (TEOS). It has been found that the fluorinated hybrid films possessed fluorinated side chains originating from PFAS as top layer, and silica network as bottom layer, which had very low surface energy and could be used as water repellent functional coatings. The outermost layer of the water-repellent film may be fully covered by the perfluoroalkyl side chains as the molar ratio of PFAS/TEOS increases up to about 0.005:1. The addition of BPA can enhance the cross-link density of fluorinated hybrid films, and make more perfluoroalkyl groups enriching at the coating film-air interface to lower the surface free energy. However, the improvement of the cross-link density of fluorinated hybrid films tends to exhibit brittleness and micro-cracks. Consequently, it can be concluded that a small BPA additive content is preferred for the formation of fluorinated hybrid films with a smooth surface and less detectable cracks.

Simple optical method to determine the porosity of porous silicon films

A simple optical method to estimate the porosity of microporous silicon films is described. The technique relies upon determination of film refractive index via measurement of the incident (Brewster) angle corresponding to a minimum in the intensity of light reflected from the air–film interface. The sample porosity is then obtained using an effective medium model. Porosities obtained using this method show general agreement with those obtained using gravimetric means and, where comparison was possible, excellent agreement with those of similarly-prepared films found by low angle X-ray reflectivity. These results confirm the general applicability of this technique to the determination of microporous silicon film porosity.

The Influence of the Solvent Evaporation Rate on the Phase Separation and Electrical Performances of Soluble Acene‐Polymer Blend Semiconductors

AbstractThe phase‐separation characteristics of spin‐cast difluorinated‐triethylsilylethynyl anthradithiophene (F‐TESADT)/poly(methyl methacrylate) (PMMA) blends are investigated with the aim of fabricating transistors with a high field‐effect mobility and stability. It is found that the presence of PMMA in the F‐TESADT/PMMA blends prevents dewetting of F‐TESADT from the substrate and provides a platform for F‐TESADT molecules to segregate and crystallize at the air–film interface. By controlling the solvent evaporation rate of the spin‐cast blend solution, it is possible to regulate the phase separation of the two components, which in turn determines the structural development of the F‐TESADT crystals on PMMA. At a low solvent evaporation rate, a bilayer structure consisting of highly ordered F‐TESAT crystals on the top and low‐trap PMMA dielectric on the bottom can be fabricated by a one‐step spin‐casting process. The use of F‐TESADT/PMMA blend films in bottom gate transistors produces much higher field‐effect mobilities and greater stability than homo F‐TESADT films because the phase‐separated interface provides an efficient pathway for charge transport.

Effect of processor temperature on film dosimetry

Optical density (OD) of a radiographic film plays an important role in radiation dosimetry, which depends on various parameters, including beam energy, depth, field size, film batch, dose, dose rate, air film interface, postexposure processing time, and temperature of the processor. Most of these parameters have been studied for Kodak XV and extended dose range (EDR) films used in radiation oncology. There is very limited information on processor temperature, which is investigated in this study. Multiple XV and EDR films were exposed in the reference condition (dmax., 10 × 10 cm2, 100 cm) to a given dose. An automatic film processor (X-Omat 5000) was used for processing films. The temperature of the processor was adjusted manually with increasing temperature. At each temperature, a set of films was processed to evaluate OD at a given dose. For both films, OD is a linear function of processor temperature in the range of 29.4–40.6°C (85–105°F) for various dose ranges. The changes in processor temperature are directly related to the dose by a quadratic function. A simple linear equation is provided for the changes in OD vs. processor temperature, which could be used for correcting dose in radiation dosimetry when film is used.

EFFECT OF FLUORINATED POLYACRYLATE CONTENT ON THE GRADIENT STRUCTURE AND SURFACE PROPERTY OF FLUORINATED/NON-FLUORINATED POLYACRYLATE LATEX BLEND FILMS

In order to obtain the gradient fluorinated/non-fluorinated polyacrylate latex blend films as cheap as possible,the fluorinated polyacrylate emulsion with small particle size was synthesized by bulk emulsion polymerization method,the acrylate copolymer emulsion with big particle size was synthesized by semicontinuous emulsion polymerization method,and then the fluorinated polyacrylate emulsion and the acrylate copolymer emulsion were mixed with a series of ratios(1/9,2/8,3/7,4/6,5/5).The blend latices were dried on clean glass at 20℃ and then annealled at 110℃/210℃ for some time(2~6 h).The effects of the fluorinated polyacrylate content on the gradient structure and surface property of the blend films were discussed.The content of fluorine on the film surface and the film section was analyzed by XPS,SEM-EDX.The surface properties and morphology were characterized by contact angle measurements and AFM.It was found that,while the content of fluorinated polyacrylate latex in the blend system was up to 30 wt%,the small and hard fluorinated polyacrylate particles were selectively gathered on the film-air interface after film-formation at room temperature,and the fluorine content increased from the film-glass interface to the film-air interface gradually in the blend films annealled 2 h at 110℃.The obtained gradient film has low surface free energy as the pure fluorinated polyacrylate and strong adhesion as the pure polyacrylate.The further increasing of fluorinated polyacrylate in the blend system helped the formation and enlargement of gradient structure,but the adhesion of film was decreased a little.The emulsion system with the content of fluorinated polyacrylate latex under 30 wt% was hard to form gradient structure.

Surface immobilisation of fluorinated polystyrene-acrylate latex nanoparticles with core-shell structure by crosslinking

Fluorinated polystyrene-acrylate (PSA) latex nanoparticles with core–shell structure were synthesised by two-stage seeded emulsion polymerisation method in the presence of reactive emulsifier DNS-86. Diallyl phthalate (DAP) and Vinyltriethoxysilicone (VTES) were used as crosslinking agent to immobilise the fluorinated copolymer on the surface of the latex film. Fourier transform infrared spectroscopy (FTIR) spectra show that fluorine and siloxane monomers were effectively involved in the emulsion copolymerisation. Transmission electron microscope (TEM) observation shows that the prepared emulsion particles had a core–shell structure with fluorinated copolymer in the shell. X-ray photoelectron spectroscopy (XPS) analysis reveals that fluorine atom has the tendency of migrating to the film–air interface and the incorporation of VTES helps the migration of fluorine atom towards the film–air interface. Water contact angle (WCA) test proved that DAP and VTES as crosslinking agent can immobilise the fluorinated copolymer on the surface of the latex films. © 2011 Canadian Society for Chemical Engineering

Self-Stratification Silicon Gradient Film Prepared by Emulsion Blend Technique

We investigated the effect of film-formation temperature andTg’s difference on the self-stratification gradient silicone film prepared by emulsion blend (poly(3-[tris(trimethyl silyloxy)silyl] propyl methacrylate-co-methyl methacrylate) /poly(butyl acrylate-co-methyl methacrylate) 50/50 by wt) (PTRIS-co-MMA/PBA-co-MMA) technique. The self-stratification film with gradient distribution of silicon was relatively easily obtained when both blend components could fully fuse to form a continuous film. Moreover, proper nonparallelTgs facilitated migration of the silicon component to the film-air interface during the film-formation and hence the gradient distribution was obtained. WhenTgof silicon-free component was 40°C, self-stratification gradient film with concentration of silicon components varying in a gradient-like manner along the overall transaction of the film was fabricated.

Novel cationic polyurethane-fluorinated acrylic hybrid latexes: Synthesis, characterization and properties

The cationic polyurethane-fluorinated acrylic (PUFA) hybrid latexes were obtained from double bond-end capped polyurethane macromonomer having quaternary ammonium groups with perfluoroalkyl acrylate (FA) by radical copolymerization. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) confirmed that the FA monomer had been introduced into the chain of the PUFA hybrid polymer. Particle size distribution (PSD) analysis showed that the particle size of PUFA increased with the increase of the FA content. TEM indicated that the PUFA hybrid possessed core–shell structure. The analysis of the contact angles (CAs), XPS and atomic force microscopy (AFM) had shown that there was a remarkable enrichment of fluorine on the film–air interface, which was more evident when the PUFA hybrid film annealed at higher temperature. At the same time, the influences of the soft segment molecular weight, the N-methyldiethanolamine (MDEA) content and the FA content on other properties such as the surface tension of the PUFA latexes, the surface free energy of the PUFA films and the thermal properties were studied. The results showed that the MDEA content had contrary influence on latex's and film's surface properties. Thermal stabilization usually brought by fluorine was not observed in our investigated systems.