scholarly journals Impact of Air Exposure Time on the Water Contact Angles of Daily Disposable Silicone Hydrogels

2019 ◽  
Vol 20 (6) ◽  
pp. 1313 ◽  
Author(s):  
Petar Eftimov ◽  
Norihiko Yokoi ◽  
Nikola Peev ◽  
Georgi Georgiev
Keyword(s):  
Surface Coating ◽  
Sessile Drop ◽  
High Surface ◽  
Tear Film ◽  
Contact Angles ◽  
Water Contact ◽  
Air Exposure ◽  
Film Stability ◽  
Silicone Hydrogel ◽  
Silicone Hydrogels

The wettability of silicone hydrogel (SiHy) contact lens (CLs) is crucial for the pre-lens tear film stability throughout the day. Therefore, sessile drop and captive bubble setups were used to study the advancing and receding water contact angles (CA) of four SiHy materials: narafilcon A (TE), senofilcon A (AOD), stenfilcon A (MD), and delefilcon A (DT). TE and AOD have 48% and 38% water content, respectively, and no surface coating. MD (54% water) implements “smart chemistry” with just 4.4% bulk silicone content, while DT has >80% water at its surface. These SiHy were subjected to continuous blink-like air exposure (10 s)/rehydration (1s) cycles for 0, 1, 2, 3, 4, 6, 8, 10, 12, 14, and 16 h. The advancing CA, which measures the rehydration propensity of the CL surface, proved to be the most sensitive parameter to discriminate between the samples. The order of performance for the entire time scale was DT > MD >> AOD ≥ TE. The extended desiccation/rehydration cycling increased the differences between the CA of DT and MD compared to AOD and TE. This suggests that the low Si surface content and the high surface hydration are major determinants of SiHy wettability.

scholarly journals Development of Superhydrophobic Cotton Fabric Using Zinc Oxide Nanoflower/Polydimethylsiloxane (PDMS) Nanocomposite Coatings

2021 ◽  
Author(s):  
Sorna Gowri Vijaya Kumar ◽  
◽  
Priyanka Prabhakar ◽  
Raj Kumar Sen ◽  
Neha Uppal ◽  
...  
Keyword(s):  
Contact Angle ◽  
Zinc Oxide ◽  
Cotton Fabric ◽  
Sessile Drop ◽  
High Surface ◽  
Average Particle Size ◽  
Volume Ratio ◽  
Average Particle ◽  
Water Contact ◽  
Scherrer Formula

Nanoflower is anticipated to become a very smart material due to its unique properties such as high surface to volume ratio. A hydrothermal method was used in this study to prepare the zinc oxide (ZnO) nanoflower and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The average particle size of the ZnO nanoflower was calculated as 21nm according to the Debye-Scherrer formula. The SEM result gives the surface morphological information of the ZnO nanoflower, which confirms the formation of the ZnO nanoflower. The ZnO nanoflower was dispersed in PDMS and coated onto cotton fabric to get the superhydrophobic fabric. The hydrophobicity was determined by measuring the water contact angle by the Sessile drop method and it was observed that coated fabrics have the highest contact angle, 140⁰ at 0.5% ZnO nanoflower concentration. The present study offers a method of fabrication of superhydrophobic cotton textile using ZnO nanoflower/PDMS polymer nanocomposites.

scholarly journals Effect of Oxygen Inhibition Layer of Universal Adhesives on Enamel Bond Fatigue Durability and Interfacial Characteristics With Different Etching Modes

2017 ◽  
Vol 42 (6) ◽  
pp. 636-645 ◽  
Author(s):  
H Ouchi ◽  
A Tsujimoto ◽  
K Nojiri ◽  
K Hirai ◽  
T Takamizawa ◽  
...  
Keyword(s):  
Sessile Drop ◽  
Contact Angles ◽  
Inhibition Layer ◽  
Universal Adhesive ◽  
Water Contact ◽  
Oxygen Inhibition ◽  
Fatigue Durability ◽  
Shear Fatigue ◽  
Universal Adhesives ◽  
Interfacial Characteristics

SUMMARY Objective: The purpose of this study was to evaluate the effect of the oxygen inhibition layer of universal adhesive on enamel bond fatigue durability and interfacial characteristics with different etching modes. Methods: The three universal adhesives used were Scotchbond Universal Adhesive (3M ESPE, St Paul, MN, USA), Adhese Universal (Ivoclar Vivadent, Schaan, Lichtenstein), and G-Premio Bond (GC, Tokyo, Japan). The initial shear bond strength and shear fatigue strength to enamel was determined in the presence and absence of the oxygen inhibition layer, with and without phosphoric acid pre-etching. The water contact angle was also measured in all groups using the sessile drop method. Results: The enamel bonding specimens with an oxygen inhibition layer showed significantly higher (p<0.05) initial shear bond strengths and shear fatigue strengths than those without, regardless of the adhesive type and etching mode. Moreover, the water contact angles on the specimens with an oxygen inhibition layer were significantly lower (p<0.05) than on those without, regardless of etching mode. Conclusion: The results of this study suggest that the oxygen inhibition layer of universal adhesives significantly increases the enamel bond fatigue durability and greatly changes interfacial characteristics, suggesting that the bond fatigue durability and interfacial characteristics of these adhesives strongly rely on its presence.

PREPARATION OF POLYMER BRUSHES FROM POLY(VINYLIDENE FLUORIDE) SURFACES BY UV IRRADIATION PRETREATMENT

2007 ◽  
Vol 14 (01) ◽  
pp. 23-30 ◽  
Author(s):  
QILAN DENG ◽  
YIWANG CHEN ◽  
WEI SUN
Keyword(s):  
Methyl Methacrylate ◽  
Uv Irradiation ◽  
Photoelectron Spectroscopy ◽  
Polymer Brushes ◽  
Vinylidene Fluoride ◽  
Contact Angles ◽  
Water Contact ◽  
Air Exposure ◽  
Poly Vinylidene Fluoride ◽  
Ft Ir

Grafting of polymer brushes from the poly(vinylidene fluoride) (PVDF) surfaces was carried out. The active species, such as peroxide and hydroperoxide, on the surface were generated via ultraviolet (UV) irradiation pretreatment in nitrogen, followed by air exposure. Homopolymer brushes of methyl methacrylate (MMA) were prepared by the surface-initiated free radical polymerization from the peroxide initiators on the PVDF surface. The peroxides formed on UV-treated and air-exposed PVDF surfaces were determined quantitatively by the reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH) in toluene. The chemical composition and topography of the graft-functionalized PVDF surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy, and atomic force microscopy (AFM). ATR FT-IR revealed an increase in the graft concentration of poly(methyl methacrylate) (PMMA) on PVDF surfaces with an increase of the UV irradiation pretreatment time. Water contact angles on PVDF surfaces were reduced by surface grafting of PMMA.

scholarly journals Thermal Atomic Layer Deposition of Yttrium Oxide Films and Their Properties in Anticorrosion and Water Repellent Coating Applications

Coatings ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 497
Author(s):  
Christian Dussarrat ◽  
Nicolas Blasco ◽  
Wontae Noh ◽  
Jooho Lee ◽  
Jamie Greer ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Yttrium Oxide ◽  
Photoelectron Spectroscopy ◽  
Silicon Oxide ◽  
Atomic Layer ◽  
Contact Angles ◽  
Water Repellent ◽  
Water Contact ◽  
Air Exposure ◽  
Layer Deposition

The thermal atomic layer deposition (ThALD) of yttrium oxide (Y2O3) was developed using the newly designed, liquid precursor, Y(EtCp)2(iPr2-amd), as the yttrium source in combination with different oxygen sources, such as ozone, water and even molecular oxygen. Saturation was observed for the growth of the Y2O3 films within an ALD window of 300 to 450 °C and a growth per cycle (GPC) up to 1.1 Å. The resulting Y2O3 films possess a smooth and crystalline structure, while avoiding any carbon and nitrogen contamination, as observed by X-ray photoelectron spectroscopy (XPS). The films showed strong resistance to fluorine-containing plasma, outperforming other resistant materials, such as silicon oxide, silicon nitride and alumina. Interestingly, the hydrophilic character exhibited by the film could be switched to hydrophobic after exposure to air, with water contact angles exceeding 90°. After annealing under N2 flow at 600 °C for 4 min, the hydrophobicity was lost, but proved recoverable after prolonged air exposure or intentional hydrocarbon exposure. The origin of these changes in hydrophobicity was examined.

scholarly journals Compliance as an Integral Part of the Dry Eye Syndrome Prevention Using Silicone Hydrogel Contact Lenses

2016 ◽  
Vol 23 (4) ◽  
pp. 201647
Author(s):  
Rimma Skrypnyk ◽  
Olga Selezneva
Keyword(s):  
Dry Eye ◽  
Contact Lenses ◽  
Tear Film ◽  
Dry Eye Syndrome ◽  
Film Stability ◽  
Silicone Hydrogel ◽  
Clinical Guidance ◽  
Schirmer’S Test ◽  
Group I ◽  
Tear Film Stability

The probability of dry eye syndrome (DES) in the patients using the Silicone-Hydrogel Contact Lenses is examined in many researches. Therefore, adhering to clinical recommendations is an important factor for DES prevention. The urgent issue is also a comprehensive assessment of functional parameters as pathogenetic base of DES.The objective of the research was tostudy DES development depending on compliance of silicone hydrogel contact lenses users.Matherials and methods. 97 patients (194 eyes) were included into the research. They formed 2 groups: group I with incomplete compliance (36 persons) and group II with complete compliance (61 persons). All the patients underwent the Norn’s test, Schirmer’s test, Jones test, tear film stability was defined. The probability of the dry eye syndrome development due to the subjective signs was also analysed.Results. The reliable decrease in the total (р<0.05) and basale lacrimation (р<0.05) indexes, the increase in osmolarity (р<0.05) and decrease in tear film stability (р<0.05) were detected in the patients who did not follow the clinical guidance during the Silicone-Hydrogel Contact Lenses wearing. In the same group the higher risk of dry eye syndrome development was verified (р<0.05).Conclusion. Compliance disorder in the patients using Silicone-Hydrogel Contact Lenses was found to induce the reliable decrease in total and basale lacrimation, increase in osmolarity and tear stability disorder. All of this factors increase the risk of dry eye syndrome.

Development of Rapid Cell Recovery System Using Temperature-Responsive Nanofiber Surfaces

2007 ◽  
Vol 342-343 ◽  
pp. 249-252 ◽  
Author(s):  
Young Gwang Ko ◽  
Hyeon Ae Jeon ◽  
Kwan Han Yoon ◽  
Young Chul Kim ◽  
Chang Hyun Ahn ◽  
...  
Keyword(s):  
Cultured Cells ◽  
Sessile Drop ◽  
Cell Attachment ◽  
Single Cells ◽  
Human Fibroblasts ◽  
Film Surface ◽  
Contact Angles ◽  
Cell Recovery ◽  
Water Contact ◽  
Initial Cell

PHBV ultrafine fibers were fabricated by electrospinning process. Electrospun PHBV fiber structures revealed randomly aligned fibers with average diameter of 400 nm. PIPAAm was grafted on the surface of PHBV nanofibrous mat by electron beam irradiation. PIPAAm-grafted PHBV mats were determined by ATR-FTIR and ESCA. Water contact angles were determined by a sessile drop method at 20 and 37. To examine the tissue compatibility, human fibroblasts were evenly seeded onto PIPAAm-grafted PHBV mat and cast film, ungrafted PHBV mat and film. Attached and spread fibroblasts on nanofibrous mat were proliferated more rapidly than that of flat film surface. Initial cell attachment on PIPAAm-grafted surfaces was higher than ungrafted surfaces. The surface property changed to hydrophilic by PIPAAm graft, which increased initial cell attachment. Detachment of single cells from PIPAAm-grafted PHBV matrixes was measured by low temperature treatment after incubation at 37. Cultured cells were rapidly detached from PIPAAm-grafted PHBV mat compared with film. With porous mats, the water molecules easily reach to grafted PIPAAm from underneath and peripheral to the attached cells, resulting in rapid hydration of grafted PIPAAm molecules and detachment of the cells.

scholarly journals Siloxane-Starch-Based Hydrophobic Coating for Multiple Recyclable Cellulosic Materials

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4977
Author(s):  
Tomasz Ganicz ◽  
Krystyna Rózga-Wijas
Keyword(s):  
High Surface ◽  
Barrier Properties ◽  
Surface Hydrophobicity ◽  
Contact Angles ◽  
Recycling Process ◽  
Water Contact ◽  
Cellulosic Materials ◽  
Circulating Water ◽  
Hydrophobic Coating ◽  
Aqueous Mixture

The results of the application of a new hydrophobization agent based on a triethoxymethylsilane and standard starch aqueous mixture for mass-produced cellulosic materials—printing paper, paperboard, and sack paper—have been evaluated to examine whether such a mixture can be used in industrial practice. The application of this agent on laboratory sheets prepared in a repetitive recycling process was performed to investigate its influence on the formation and properties of the products, as well as the contamination of circulating water. Measurements of the water contact angle, Cobb tests, and water penetration dynamics (PDA) were performed to test the barrier properties of the resulting materials. The effects of the applied coatings and recycling process on the paper’s tensile strength, tear index, roughness, air permeance, and ISO brightness were studied. Studies have proven that this formulation imparts relatively high surface hydrophobicity to all materials tested (contact angles above 100°) and a significant improvement in barrier properties while maintaining good mechanical and optical performance. The agent also does not interfere with the pulping and re-forming processes during recycling and increases circulation water contamination to an acceptable degree. Attenuated total reflectance Fourier-transform infrared (FT-IR) spectra of the paper samples revealed the presence of a polysiloxane network on the surface.

Effects of Air Exposure Time and Annealing Temperature on Superhydrophobic Surface of Titanium Dioxide Films

2017 ◽  
Vol 751 ◽  
pp. 137-142
Author(s):  
S.Tipawan Khlayboonme ◽  
Warawoot Thowladda
Keyword(s):  
Contact Angle ◽  
Surface Morphology ◽  
Exposure Time ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Contact Angles ◽  
Angle Measurement ◽  
Elemental Distribution ◽  
Water Contact ◽  
Air Exposure

TiO2 thin films coated on glass substrates for self-cleaning applications were prepared by sol-gel dip-coating technique. The influence of annealing temperature and air exposure time on wettability was investigated by a water contact-angle measurement. Thermal annealing at temperatures of 100, 200 and 300 °C in air were conducted to the films. Surface morphology of the films was observed by FE-SEM. Elemental distribution and optical properties were examined by EDX mapping and UV-Vis transmission spectroscopy, respectively. Atomic bonding was confirmed by FTIR. The contact angle reached a maximum when the films were annealed at 200 °C. The contact angles of the as-synthesized films were 61.4±2.7°. During storage in air for 20 days, the contact angles increased to 143.1±2.1°. The films were further reannealed with 100 °C for 20 min, the contact angles were enhanced to 153.1±1.3°. The association of contact angle among the surface morphology, elemental distribution and atomic bonding of the films will be discussed.

SURFACE CHARACTERIZATION AND HEMOCOMPATIBILITY OF HEPARINIZED 316L STAINLESS STEEL

2008 ◽  
Vol 20 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Tzu-Wen Chuang ◽  
Feng-Huei Lin
Keyword(s):  
Stainless Steel ◽  
Surface Characterization ◽  
316L Stainless Steel ◽  
Sessile Drop ◽  
Contact Angles ◽  
Hexamethylene Diisocyanate ◽  
Water Contact ◽  
Arterial Restenosis ◽  
Conformational Freedom ◽  
Surface Coupling

Poor compatibility between blood and metallic coronary artery stents is one reason for arterial restenosis. Immobilization of heparin on stent's surface is feasible for improving compatibility. We examined possible surface-coupling agents for anticoagulant agent immobilization. Hexamethylene diisocyanate (HMDI) was examined as surface-coupling agent to activate 316L stainless steel (e.g. stent material). Afterwards, we grafted PEG on the HMDI activated surface to provide heparin with higher conformational freedom and a more hydrophilic environment. The effectiveness of HMDI activated and PEG grafted surface was confirmed by FTIR, XPS, and water contact angle test. Heparin was then immobilized onto the activated 316L stainless steel. The heparin surface density was 9.5 μg/cm2. Sessile drop water contact angles showed that the heparingrafted surface is even more hydrophilic than the PEG grafted one. The function of grafted heparin was evaluated by antithrombrin III (ATIII) adsorption testing and SEM. The surface with heparin grafting shows better ATIII binding ability and hemocompatibility than the native one.

Porous Fluorinated Graphene and ZIF-67 Composites with Hydrophobic-Oleophilic Properties Towards Oil and Organic Solvent Sorption

2020 ◽  
Vol 20 (5) ◽  
pp. 2930-2938 ◽  
Author(s):  
R. Yogapriya ◽  
K. K. R. Datta
Keyword(s):  
Oil Recovery ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Contact Angles ◽  
Future Research ◽  
Water Contact ◽  
Water Separation ◽  
Oil Water ◽  
Fluorinated Graphene

Designing hydrophobic-oleophilic sorbent materials have gained significant interest owing to its potential applications in self-cleaning technologies particularly oil-water separation. The crucial factors remain in the future research of designing materials with high performance hydrophobicoleophilic properties include facile synthesis, low-density, reusability and ecofriendly. Herein, we develop porous hydrophobic-oleophilic nanoarchitecture based on 2D fluorinated graphene (FG) supported cobalt based zeolite imidazole framework (ZIF-67) by solution assisted self-assembly. The key features of the work include in-situ growth and assembly of ZIF-67 over functionalized fluorinated graphene f-FG macrostructures, high surface area and solution processable and spray coated sponge. Methodical characterization of f-FG@ZIF-67 composites, followed by measuring water contact angles by contact angle goniometer. Furthermore, the assessment of sorption capacity of oils and organics followed by oil recovery from oil-water mixtures, excellent chemical and physical stabilities were displayed by these hydrophobic-oleophilic composites.

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