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The purpose of the present study is to evaluate the impact of simplified ethanol-wet bonding (EWB) and hydrophobic coating (HC) on the three adhesives. We collected 105 fresh human molars and randomly divided them into three groups according to the three types of adhesives: Single Bond (SB), Gluma Comfort Bond (GB), and Tetric N-Bond (TB). Then, each group was further divided into five subgroups based on different bonding schemes: (1) Water wetting bonding (WWB); (2) EWB for 1 min (EWB 1); (3) EWB for 2 min (EWB 2); (4) EWB for 1 min combined with HC (EWB 1 + HC); and (5) HC. We evaluated the micro-tensile bonding strength (MTBS), fracture types, hybrid layer and resin tags of the specimens. At 24 h, SB (EWB 2), GB (EWB 2), TB (EWB 2), GB (HC), TB (HC), TB (EWB 1) and TB (EWB 1 + HC) groups revealed significant improvement in MTBS (p＜0.05); After 6 months, SB (EWB 1 + HC), GB (EWB 2), and TB (HC) groups showed no significant reduction in MTBS (p＜0.05). Besides, EWB 2 has the most noticeable effect on both hybrid layer and resin tags in all adhesives; EWB 1 + HC or HC alone scheme increase the number and length of resin tags in partly adhesives. Simplified ethanol wetting technology can increase the bond strength, durability, and quality of the three adhesives, and its effect depends on the wetting time. In this study, ethanol wetting for 2 min improved the adhesion properties significantly. [ABSTRACT FROM AUTHOR]

Thin dielectric stacks comprising a main insulating layer and a hydrophobic top coating are commonly used in low voltage electrowetting systems. However, in most cases, thin dielectrics fail to endure persistent electrowetting testing at high voltages, namely beyond the saturation onset, as electrolysis indicates dielec-tric failure. Careful sample inspection via optical microscopy revealed possible local delamination of the top coating under high electric fields. Thus, improvement in the adhesion strength of the hydrophobic top coating to the main dielectric is attempted through a plasma-deposited fluorocarbon interlayer. Interestingly enough the proposed dielectric stack exhibited (a) resistance to dielectric breakdown, (b) higher contact an-gle modulation range and (c) electrowetting cycle reversibility. Appearance of electrolysis in the saturation regime is inhibited, suggesting the use of this hydrophobic dielectric stack for the design of more efficient electrowetting systems. The possible causes of the improved performance are investigated by nanoscratch characterization. [ABSTRACT FROM AUTHOR]

The model presented in this paper is the first step towards explaining the mechanisms of ice adhesion. Considerable work, however, remains to validate each term included in the model due to the lack of physical constants and parameters related to rough surfaces. The ice adhesion model at the ice-substrate interface is based on water behavior before and after freezing, substrate roughness and ice type. Within nanoseconds following impact, water occupies the substrate surface either partially before freezing when drops or rivulets form, or totally when a film is formed. The ice surface area in contact with the substrate is reduced due to the space between drops and rivulets. Due to the electrostatic attraction between water and substrate molecules, ice sticks to the substrate. The electrostatic force depends on the intensity of this bond, which is related to the work needed to maintain the drop shape over the surface and the distance between the water and substrate molecules. The water can also sink in and fill the cavities formed by adjacent surface roughness peaks when the surface tension force is less than the water pressure force. Following the phase change, on the order of microseconds for rime ice, and milliseconds for glaze ice, the ice mechanically locks onto the surface and must be broken down to be shed. This paper shows the development of a phenomenological model to predict the cohesive failure of ice, one that does not take into consideration rime ice porosity. The model assumes that ice near its freezing point is subject to internal and external strains, and that its cohesive strength corresponds to the failure stress. The failure stress is dependent on grain size and creep involving grain boundary sliding in a polycrystalline material at elevated temperatures. The next steps in the development of the model are to quantify the physical parameters, validate an idealized rough surface, as well as evaluate the effects of rime ice porosity and small grain sizes. [ABSTRACT FROM AUTHOR]