Producing superhydrophobic/oleophobic coatings on Cultural Heritage building materials

AbstractWater is the main vehicle of decay agents in Cultural Heritage building materials exposed to weathering. In this work, a simple method to produce superhydrophobic/oleophobic coatings building materials, including under outdoors conditions, has been developed. In addition, a study of the behavior of the developed coatings on different substrates (limestone, granite, concrete and wood) is reported. The addition of 40 nm-SiO2nanoparticles to a fluoroalkylsilane reduces surface energy and produces a Cassie-Baxter surface in all the materials evaluated. It promotes high static contact angle values of around 160°, and a contact angle hysteresis of around 3°, giving rise to repellence. The building surfaces also demonstrate an excellent self-cleaning performance. The coatings maintain the building materials esthetics as required in the Cultural Heritage field. Finally, the coating presents a long-lasting performance due to condensation reactions producing effective grafting to the four building materials evaluated.

Download Full-text

A Simple Method to Create Superhydrophobic Aluminium Surfaces

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.2874 ◽

2012 ◽

Vol 706-709 ◽

pp. 2874-2879 ◽

Cited By ~ 10

Author(s):

R. Jafari ◽

Masoud Farzaneh

Keyword(s):

Contact Angle ◽

Stearic Acid ◽

Synergistic Effects ◽

Low Cost ◽

Contact Angle Hysteresis ◽

Spray Coating ◽

Superhydrophobic Surfaces ◽

Water Contact ◽

Simple Method ◽

Static Contact

Superhydrophobic surfaces were prepared using a very simple and low-cost method by spray coating. A high static water contact angle of about 154° was obtained by deposition of stearic acid on an aluminium alloy. However, this coating demonstrated a high contact angle hysteresis (~ 30º). On the other hand, superhydrophobic surfaces with a static contact angle of about 162º and 158º, and a low contact angle hysteresis of about 3º and 5º were respectively obtained by incorporating nanoparticles of SiO2and CaCO3in stearic acid. The excellent resulting hydrophobicity is attributed to the synergistic effects of micro/nanoroughness and low surface energy. A study of the wettability of these surfaces at temperatures ranging from 20 to-10 °C showed that the superhydrophobic surface becomes rather hydrophobic at supercooled temperatures.

Download Full-text

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

Biomimetics ◽

10.3390/biomimetics6020038 ◽

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.

Download Full-text

The Surface Modification with Fluorocarbon Thin Films for the Prevention of Stiction in Mems

MRS Proceedings ◽

10.1557/proc-518-143 ◽

1998 ◽

Vol 518 ◽

Cited By ~ 5

Author(s):

Sang-Ho Lee ◽

Myong-Jong Kwon ◽

Jin-Goo Park ◽

Yong-Kweon Kim ◽

Hyung-Jae Shin

Keyword(s):

Contact Angle ◽

Contact Angle Hysteresis ◽

Contact Angles ◽

Fluorocarbon Films ◽

Perfluorodecanoic Acid ◽

Large Hysteresis ◽

Static Contact ◽

Receding Contact ◽

Highly Hydrophobic ◽

Receding Contact Angle

AbstractHighly hydrophobic fluorocarbon films were prepared by the vapor phase (VP) deposition method in a vacuum chamber using both liquid (3M's FC40, FC722) and solid sources (perfluorodecanoic acid (CF3(CF2)8COOH), perfluorododecane (C12F26)) on Al, Si and oxide coated wafers. The highest static contact angles of water were measured on films deposited on aluminum substrate. But relatively lower contact angles were obtained on the films on Si and oxide wafers. The advancing and receding contact angle analysis using a captive drop method showed a large contact angle hysteresis (ΔH) on the VP deposited fluorocarbon films. AFM study showed poor film coverage on the surface with large hysteresis. FTIR-ATR analysis positively revealed the stretching band of CF2 groups on the VP deposited substrates. The thermal stability of films was measured at 150°C in air and nitrogen atmospheres as a function of time. The rapid decrease of contact angles was observed on VP deposited FC and PFDA films in air. However, no decrease of contact angle on them was observed in N2.

Download Full-text

Marangoni Flow-Induced Droplet Deformation for Micromirror Applications

ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer, Volume 3 ◽

10.1115/mnhmt2009-18434 ◽

2009 ◽

Author(s):

Yen-Wen Lu ◽

Rakesh Dhull

Keyword(s):

Contact Angle ◽

Contact Angle Hysteresis ◽

Marangoni Flow ◽

Droplet Deformation ◽

Simple Method ◽

Tilting Angle

A simple method that utilizes Marangoni flow to create droplet deformation and to tilt micro-objects is presented. Contact angle hysteresis is employed to prevent the droplet from rolling away from the position. The device consists of a micromirror placed on the droplet, and can produce a 6.5° tilting angle when actuated at 30 V. It also demonstrates its scanning capability and potential as a micromirror.

Download Full-text

Preparation of Superhydrophobic Steel Surfaces with Chemical Stability and Corrosion

Coatings ◽

10.3390/coatings9060398 ◽

2019 ◽

Vol 9 (6) ◽

pp. 398 ◽

Cited By ~ 8

Author(s):

Chongwei Du ◽

Xiaoyan He ◽

Feng Tian ◽

Xiuqin Bai ◽

Chengqing Yuan

Keyword(s):

Contact Angle ◽

Corrosion Resistance ◽

Carbon Steel ◽

Chemical Stability ◽

Superhydrophobic Surface ◽

Contact Angle Hysteresis ◽

Water Contact ◽

Simple Method ◽

Q235 Carbon Steel ◽

Steel Surfaces

Corrosion seriously limits the long-term application of Q235 carbon steel. Herein, a simple fabrication method was used to fabricate superhydrophobic surfaces on Q235 carbon steel for anticorrosion application. The combination of structure and the grafted low-surface-energy material contributed to the formation of superhydrophobic steel surfaces, which exhibited a water contact angle of 161.6° and a contact angle hysteresis of 0.8°. Meanwhile, the as-prepared superhydrophobic surface showed repellent toward different solutions with pH ranging from 1 to 14, presenting excellent chemical stability. Moreover, the acid corrosive liquid (HCl solution with pH of 1) maintained sphere-like shape on the as-prepared superhydrophobic surface at room temperature, indicating superior corrosion resistance. This work provides a simple method to fabricate superhydrophobic steel surfaces with chemical stability and corrosion resistance.

Download Full-text

Superhydrophobic Fabrics with Mechanical Durability Prepared by a Two-Step Plasma Processing Method

Coatings ◽

10.3390/coatings8100351 ◽

2018 ◽

Vol 8 (10) ◽

pp. 351 ◽

Cited By ~ 7

Author(s):

Kosmas Ellinas ◽

Angeliki Tserepi ◽

Evangelos Gogolides

Keyword(s):

Surface Energy ◽

Plasma Deposition ◽

Contact Angle Hysteresis ◽

Plasma Processing ◽

High Water ◽

Contact Angles ◽

Processing Method ◽

Static Contact ◽

Mechanical Durability ◽

Fabric Surface

Most studies on superhydrophobic fabrics focus on their realization using additive manufacturing (bottom-up) techniques. Here we present the direct modification of three different fabrics using a plasma-based method to obtain anti-adhesive and self-cleaning properties. A two-step plasma processing method is used: (a) for the creation of micro-nanoscale features on the fabric surface (plasma texturing step) and (b) the minimization of the fabric surface energy (by a short plasma deposition step of a very thin, low surface energy layer). The entire process takes only 14 min and all fabrics after processing exhibit high water static contact angles (WSCA > 150°), low contact angle hysteresis (CAH < 7°) and advantageous mechanical durability against hand-rumpling. The method is simple and generic, and it can be therefore expanded to other polymeric fabrics (i.e., acrylic) in addition to polyester, without any limitation rising from the weaving characteristics of the fabric or the starting nature of the material (i.e., hydrophobic or hydrophilic).

Download Full-text

Drop mobility on superhydrophobic microstructured surfaces with wettability contrasts

Soft Matter ◽

10.1039/c8sm01762j ◽

2018 ◽

Vol 14 (46) ◽

pp. 9418-9424 ◽

Cited By ~ 8

Author(s):

Yutaku Kita ◽

Coinneach Mackenzie Dover ◽

Alexandros Askounis ◽

Yasuyuki Takata ◽

Khellil Sefiane

Keyword(s):

Contact Angle ◽

Surface Energy ◽

Energy Analysis ◽

Contact Angle Hysteresis ◽

Drop Velocity ◽

Microstructured Surfaces ◽

Drop Motion ◽

Surface Energy Analysis

Influence of wettability contrasts and contact angle hysteresis on drop velocity and surface energy analysis describing the drop motion.

Download Full-text

Use of Contact Angle Hysteresis in Estimating Thin Polymer Film Surface Energy and Wettability

Materials, Nondestructive Evaluation, and Pressure Vessels and Piping ◽

10.1115/imece2006-16173 ◽

2006 ◽

Author(s):

I. S. Bayer ◽

C. M. Megaridis ◽

J. Zhang ◽

D. Gamota

Keyword(s):

Surface Tension ◽

Contact Angle ◽

Surface Energy ◽

Uv Radiation ◽

Contact Angle Hysteresis ◽

Estimation Methods ◽

Thin Polymer Film ◽

Energy Estimation ◽

Surface Energies ◽

Polar Probe

A recent surface energy estimation method [1] interpreting contact angle hysteresis measurements was used to estimate surface energy of various commercially important polymer films including UV radiation cross-linked acrylic based monomer systems. The validity of the method was tested on highly hydrophobic non-polar amorphous fluoro-polymers using a number of polar and low surface tension liquids. Contact angle hysteresis was present on these surfaces even though surface morphology of the solution processed fluoro-polymers is close to ideal. Estimated surface energies using such probe liquids were consistent varying slightly with the probe liquid type. On such highly ordered and non-polar polymer surfaces use of polar and low surface tension liquids results in accurate surface energy estimation. However, use of polar probe liquids commonly employed in surface energy estimation methods, such as, Harmonic mean (HM), Geometric mean (GM) or Lewis Acid-Base method (LWAB) on polar surfaces such as polyester resulted in inconsistent surface energy values. To strengthen this observation, the ASTM surface energy estimation procedure (ASTM D2578 04a) developed for polyethylene and polypropylene surfaces (both non-polar) was employed on a sample polar polyester surface using the ASTM probe liquids. Results showed inconsistent surface energy values supporting the conclusion that care must be exercised during use of polar probe liquids in estimating surface energy on polar polymers with the contact angle hysteresis method. Finally, UV radiation cross-linkable acrylic polymer surface energies were estimated with the hysteresis method. Surface energy results were consistent based on five different probe liquids. It was observed that surface energy of the cross-linked monomer networks decreased slightly with increasing UV curing time.

Download Full-text