Applicability of photochemically generated pendant benzoyl peroxides in both “grafting from” and “grafting to” techniques

2013 ◽  
Vol 67 (1) ◽  
Author(s):  
Jaroslav Mosnáček ◽  
Ivan Lukáč ◽  
Monica Bertoldo ◽  
Francesco Ciardelli
Keyword(s):  
Contact Angle ◽  
Spectroscopic Analysis ◽  
Film Surface ◽  
Contact Angles ◽  
Surface Grafting ◽  
Copolymer Films ◽  
Styrene Copolymers ◽  
Infrared Spectroscopic Analysis ◽  
Methyl Metacrylate ◽  
Grafting From

AbstractMethyl methacrylate and styrene copolymers containing pendant benzil groups, such as 1-[4-(2-methacroyloxyethoxy)phenyl]-2-phenyl-1,2-ethanedione-co-methyl metacrylate (BzMA/MMA), 1-[4-(2-methacroyloxyethoxy)phenyl]-2-phenyl-1,2-ethanedione-co-styrene (BzMA/S), and 1-phenyl-2-(4-propenoylphenyl)-1,2-ethanedione-co-styrene (PCOCO/S), were prepared and used as precursors for photochemically generated pendant benzoyl peroxides. Decomposition of the pendant benzoyl peroxides was subsequently used in grafting processes. Either irradiation or a combination of irradiation with subsequent thermal treatment was adopted for grafting a thin layer of BzMA/MMA copolymer onto the surface of LDPE films. The grafting resulted in a significant decrease in contact angle of the film surface. The same activation strategy was successfully adopted to initiate the polymerisation of acrylic or methacrylic acids from the surface of styrene copolymer films containing the initiator precursor in the polymer side chains (BzMA/S and PCOCO/S). The successful surface grafting was proved by contact angles measurement as well as by infrared spectroscopic analysis.

The Study on the Synthesis of Polyfluoroacrylate

2013 ◽  
Vol 395-396 ◽  
pp. 351-354
Author(s):  
Qin Huan Yang
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Polymer Film ◽  
Water Contact Angle ◽  
Film Surface ◽  
Contact Angles ◽  
Fluoride Content ◽  
Water Contact ◽  
Copolymer Films ◽  
High Fluoride

Cationic polyfluoroacrylate has been synthesized in the dual presence of cationic and non-ionic emulsifiers. Optimization studies indicated that the optimal proportions of cationic emulsifier 1631 and non-ionic emulsifiers FSA and AEO-9 were 1.75%, 1.25%, and 0.08%, respectively. Under these conditions, the conversion to the polymer was 92.5%, the particle size was 142 nm, and the water contact angle on a polymer film surface was 94.0°. With increasing dosage of hydrocarbon emulsifier, the water contact angles of copolymer films decreased dramatically. The magnitude of this decrease for a polymer with low fluoride content was greater than that for a polymer with high fluoride content. The fluorinated emulsifier FSA behaved similarly to the hydrocarbon emulsifier.

Fabrication of Ultrahydrophobic ZnO by Vapor Phase Transport

2011 ◽  
Vol 282-283 ◽  
pp. 753-756
Author(s):  
Zhi Jun Xi ◽  
Gang Li ◽  
Li Ming Lu
Keyword(s):  
Contact Angle ◽  
Vapor Phase ◽  
Film Surface ◽  
Contact Angles ◽  
Nickel Surface ◽  
Zno Film ◽  
Vapor Phase Transport ◽  
Si Substrates ◽  
Vapor Phase Transport Method ◽  
Phase Transport

A ultrahydrophobic ZnO film was synthesized on the Si substrates by a novel vapor phase transport method. The surface structural properties of as-synthesized ZnO film was characterized using scanning electron micrograph (SEM). The contact angles and the rolling angles on such films were measured through an optical contact angle meter. Wettability studies revealed the films exhibited a ultrahydrophobic behaviour with a higher contact angle of 166.8°±6.8° and lower rolling angle of less than 2°-a water droplet moved easily on the surface. SEM showed that compared with pure smooth nickel surface, a lotus-like structrure with micro-nano hierarchical papillae was obviously observed on the ultrahydrophobic ZnO film surface. Such a speccial surface microstructure may result in the ultrahydrophobicity.

Correlation of Superhydrophilicity and Photocatalytic Activity in the TiO2-Based Porous Thin Films

2006 ◽  
Vol 510-511 ◽  
pp. 54-57 ◽  
Author(s):  
Seung Yong Chai ◽  
Jin Koo Park ◽  
Ho Kun Kim ◽  
Wan In Lee
Keyword(s):  
Contact Angle ◽  
Photocatalytic Activity ◽  
Uv Irradiation ◽  
Uv Light ◽  
Irradiation Time ◽  
Colloidal Suspension ◽  
Initial Point ◽  
Film Surface ◽  
Contact Angles ◽  
Tio2 Films

Transparent TiO2, WO3-TiO2, and MoO3-TiO2 films were prepared by spin-coating each colloidal suspension. The monolayer coverage of WO3 on the surface of TiO2 greatly increased the photocatalytic activity in the decomposition of gaseous 2-propanol, whereas the addition of MoO3 considerably decreased the photocatalytic reaction of TiO2. For the estimation of superhydrophilicity, the change of contact angles between the water drop and the film surface was measured as a function of UV-irradiation time. The measured contact angle of WO3-TiO2 film was considerably lower than that of TiO2 before the UV-irradiation, and it decreased to the minimum value about 4 times faster than that of pure TiO2 films with the irradiation of UV light. On the other hand, MoO3-TiO2 films showed a low contact angle at initial point, but their contact angle was very slowly decreased under the UV light. The initial low contact angles suggest the high hydrophilic character of WO3-TiO2 and MoO3-TiO2 films with high Lewis surface acidities. The observed trend suggests that the superhydrophilicity is closely related to the photocatalytic activity.

Preparation of a Superhydrophobic Carbon Dilm by a Novel Vapor Phase Transport Process

2010 ◽  
Vol 168-170 ◽  
pp. 1065-1068 ◽  
Author(s):  
Gang Li
Keyword(s):  
Contact Angle ◽  
Vapor Phase ◽  
Carbon Film ◽  
Film Surface ◽  
Contact Angles ◽  
Pure Nickel ◽  
Nickel Surface ◽  
Contact Mode ◽  
Vapor Phase Transport ◽  
Phase Transport

Extreme water repellency is greatly desired for anticontamination and self-cleaning applications in new building walling materials. A superhydrophobic carbon film was fabricated on the pure nickel substrates by a novel vapor phase transport method. The surface of morphologies of the pure nickel surface was characterized using a non-contact mode of atomic force microscope (AFM) and the structural properties of as-grown carbon film was characterized using scanning electron micrograph (SEM). The contact angles and the rolling angles on such films were measured through an optical contact angle meter. Wettability studies revealed the films exhibited a superhydrophobic behaviour with a higher contact angle of 160.7°±2.1° and lower rolling angle of less than 4°-a water droplet moved easily on the surface. SEM showed that compared with pure smooth nickel surface, a lotus-like structrure with micro-nano hierarchical papillae was obviously observed on the superhydrobic carbon film surface. Such a speccial surface microstructure may result in the superhydrophobicity.

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

Comparative studies of nitrogen plasma and argon plasma treatment on the strength of PBO fibre reinforced high-temperature resistant thermoplastic composite

2021 ◽  
pp. 095400832098729
Author(s):  
K Sudheendra ◽  
Jennifer Vinodhini ◽  
M Govindaraju ◽  
Shantanu Bhowmik
Keyword(s):  
Contact Angle ◽  
High Temperature ◽  
Plasma Treatment ◽  
Sessile Drop ◽  
Dynamic Contact Angle ◽  
Argon Plasma ◽  
Film Surface ◽  
Fibre Surface ◽  
Nitrogen Plasma ◽  
Thermoplastic Composite

The study involves the processing of a novel poly [1, 4-phenylene-cis-benzobisoxazole] (PBO) fibre reinforced high-temperature thermoplastic composite with polyaryletherketone (PAEK) as the matrix. The PBO fibre and the PAEK film surface was modified using the method of argon and nitrogen plasma treatment. The investigation primarily focuses on evaluating the tensile properties of the fabricated laminates and correlating it with the effect of plasma treatment, surface characteristics, and its fracture surface. A 5% decrease in tensile strength was observed post argon plasma treatment while a 27% increase in strength was observed post nitrogen plasma treatment. The morphology of the failure surface was investigated by scanning electron microscopy and an interfacial failure was observed. Furthermore, the effect of plasma on the wettability of PBO fibres and PAEK film surface was confirmed by the Dynamic Contact Angle analysis and sessile drop method respectively. FTIR spectral analysis was done to investigate the effect of plasma treatment on the chemical structure on the surface. The results of the wettability study showed that the argon plasma treatment of the fibre surface increased its hydrophobicity while nitrogen plasma treatment resulted in the reduction of contact angle.

scholarly journals Biomimetic Approach for the Elaboration of Highly Hydrophobic Surfaces: Study of the Links between Morphology and Wettability

Biomimetics ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 38
Author(s):  
Quentin Legrand ◽  
Stephane Benayoun ◽  
Stephane Valette
Keyword(s):  
Contact Angle ◽  
Ginkgo Biloba ◽  
Contact Angle Hysteresis ◽  
Contact Angles ◽  
Textured Surfaces ◽  
Replication Process ◽  
Wetting Behavior ◽  
Static Contact ◽  
Biomimetic Approach ◽  
Highly Hydrophobic

This investigation of morphology-wetting links was performed using a biomimetic approach. Three natural leaves’ surfaces were studied: two bamboo varieties and Ginkgo Biloba. Multiscale surface topographies were analyzed by SEM observations, FFT, and Gaussian filtering. A PDMS replicating protocol of natural surfaces was proposed in order to study the purely morphological contribution to wetting. High static contact angles, close to 135∘, were measured on PDMS replicated surfaces. Compared to flat PDMS, the increase in static contact angle due to purely morphological contribution was around 20∘. Such an increase in contact angle was obtained despite loss of the nanometric scale during the replication process. Moreover, a significant decrease of the hysteresis contact angle was measured on PDMS replicas. The value of the contact angle hysteresis moved from 40∘ for flat PDMS to less than 10∘ for textured replicated surfaces. The wetting behavior of multiscale textured surfaces was then studied in the frame of the Wenzel and Cassie–Baxter models. Whereas the classical laws made it possible to describe the wetting behavior of the ginkgo biloba replications, a hierarchical model was developed to depict the wetting behavior of both bamboo species.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

scholarly journals Fabrication of elastic, conductive, wear-resistant superhydrophobic composite material

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seyed Mehran Mirmohammadi ◽  
Sasha Hoshian ◽  
Ville P. Jokinen ◽  
Sami Franssila
Keyword(s):  
Contact Angle ◽  
Composite Material ◽  
Contact Angles ◽  
Wet Etching ◽  
Sliding Angle ◽  
Electrically Conductive ◽  
Wear Resistant ◽  
Nanoscale Structures ◽  
Mechanical Abrasion ◽  
Mechanical Durability

AbstractA polydimethylsiloxane (PDMS)/Cu superhydrophobic composite material is fabricated by wet etching, electroless plating, and polymer casting. The surface topography of the material emerges from hierarchical micro/nanoscale structures of etched aluminum, which are rigorously copied by plated copper. The resulting material is superhydrophobic (contact angle > 170°, sliding angle < 7° with 7 µL droplets), electrically conductive, elastic and wear resistant. The mechanical durability of both the superhydrophobicity and the metallic conductivity are the key advantages of this material. The material is robust against mechanical abrasion (1000 cycles): the contact angles were only marginally lowered, the sliding angles remained below 10°, and the material retained its superhydrophobicity. The resistivity varied from 0.7 × 10–5 Ωm (virgin) to 5 × 10–5 Ωm (1000 abrasion cycles) and 30 × 10–5 Ωm (3000 abrasion cycles). The material also underwent 10,000 cycles of stretching and bending, which led to only minor changes in superhydrophobicity and the resistivity remained below 90 × 10–5 Ωm.

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