Purpose: This paper is a review of wetting contact angle definition and measurement, wettability of contact lens, impact of tear film and contact lens solution on wetting angle. Also, the clinical performance of these parameters will be discussed. Methods: For this review article, the data about contact lens wettability and wetting angle published in the PubMed were used. Based on inclusion (publication year between 1975 and 2017, relevance to the title and the field of study, key references) and exclusion (dissimilarity to the topics) criteria, 66 articles were studied carefully. Conclusion: Several parameters including oxygen permeability, lens material, edge design, lens rigidity, lens thickness, and surface treatment methods are effective on patient`s comfortability. If all these factors are assumed to be under control and are not subject to any changes, wettability as a variable could be an important factor contributing to patient comfort. The relationships between the contact lens wetting angle, wettability, and comfortability considering multiple factors, are controversial that need more research in this field.

Contact angle is the best criteria for evaluating the wettability and surface energy. Accurate measurement of contact angle enebales the coating and paint manufactures to produce paints with diverse wettability, adhesion and durability. Numerous methods have been utilized for measuring the contact angle, where each has its pros and cons. Based on the materials being tested and expectation of researchers, the suitable method must be selected. In this study, methods for measuring contact angle have been introduced and advances in these methods are investigated. This paper educates the researchers to choose the best technique for measuring the contact angle and achieve acceptable and reliable results.

Contact angle has an important effect on the dynamic behavior of a droplet during its impact onto a solid surface; this behavior includes deformation, spreading and even rebounding of the droplet from the surface. In this paper, the effect of contact angle during droplet impact is studied and numerically simulated. First, using molecular-kinetic theory and based on the newly available research in this field, a correlation for determining the dynamic contact angle during droplet impact is obtained. This correlation is then implemented in the numerical model used to simulate the process. The results of the numerical model are compared with those of the experiments and those of the previous models (using an equilibrium contact angle; two advancing and receding contact angles). Model predictions agreed well with experimental measurements; this validated the model results for the droplet deformation during the impact. The results show that using the molecular-kinetic theory in modeling contact angle prevents the spreading-and-recoiling oscillations of the droplet that are seen when an equilibrium contact angle is used. Compared to the model with advancing and receding contact angles, the molecular-kinetic theory results in a better prediction of the time and value of the maximum and minimum spread of the droplet on the solid surface. Based on the results of the developed model, a critical maximum spread and two regions of droplet spreading or rebounding from the surface are defined. Next in the paper, an analytical model is presented to study the effect of contact angle on the droplet maximum spread. The results of this model show that for low Capillary numbers (Ca) with an increase of the equilibrium contact angle or a decrease of We number, the maximum spread of the droplet is decreased and becomes less dependent on Re number. In contrast, the maximum spread for high We numbers or low equilibrium contact angles is increased and becomes more dependent on Re number.

wettability of pharmaceutical powders is an important controlling factor in preparation of dispersed systems, coating and dissolution rates. This investigation is attempted to find quantitative relationships between wettability of pharmaceutical powders and chemical structure descriptors. The resulting equations (QSPRs) indicate the structural characteristics determining the wettability and they are predictive of wettability of other compounds. Structural parameters were determined mainly by theoretical chemistry software’s and also using group contributions. Statistical analyses showed that the most significant parameters controlling contact angles of different series of pharmaceutical powders were the highest atomic charge on the hydrogen bonding hydrogens and the nucleophilic superdelocalizability index. The other parameters of importance included the energy of vaporization, number of oxygen or nitrogen atoms, reentrant accessible surface area, the most negative atomic charge on heteroatom’s of a molecule, number of hydrogen bonding hydrogens and solubility parameter. The barbiturates and sulfonamides were also analyzed separately resulting in statistically better equations in case of sulfonamides.

Background and Objectives: Different wood polymers have different properties compared to solid wood. Research has further investigated the physical and mechanical changes of these products. Therefore, this study was conducted to investigate the thermal behavior and drop contact angle of furfurylated poplar wood polymer. Materials and Methods: Wood polymer samples were performed by saturation under pressure and polymerization of furfuryl alcohol monomer with heat catalyst. Wood samples were prepared in two levels of low and high level of furfurylation by increasing the weight percentage gain by 25. 08% and 58. 83%, respectively. Dimensional stability was assessed by long-term immersion according to ASTM D-4442 standard, drop contact angle by deionized water drip method and thermal behavior of samples by TGA (Thermogravimetric Analysis) and DTG (Derivative Thermogravimetry) techniques. Results: The results showed that volumetric swelling and water uptake of saturated samples decreased compared to control sample. Furfuryl alcohol is a polar monomer that enters the cell wall after penetrating the wood and swells the walls after polymerization, thus reducing the water absorption capacity of the wall and leaving less room for swelling. The drop contact angle was increased compared to the control samples and the highest drop angle was obtained at high level furfurylation. By reducing the spaces of moisture absorption and less water penetration inside the pores of the wood, the drop contact angle and the wettability of the wood-polymer will be reduced. The results of thermal analysis showed that with furfurylation and increasing its level, changes in TGA and DTG diagrams occur. DTG results showed that in the first phase, the amount of energy released is lower due to the high burning temperature of cellulose and the stability of the furfurylated specimens. In the second phase, the furfurylated wood-polymer showed greater thermal stability than the control and this stability increased with increasing the level of furfurylation. In the third phase, the samples of furfurylated wood-polymer at low and high levels had less energy released than the control samples. At this stage, the compounds resulting from the thermal degradation of cellulose are reduced and the flammable material is reduced compared to the control samples, resulting in a reduced energy release. In the third phase, the necessary energy is provided to break the bonds and is spent on igniting gases and tar. Conclusion: According to the findings, furfurylated poplar wood-polymer has less water absorption and volumetric swelling than the control samples and undergoes less physical changes due to less water absorption and volumetric swelling. It can be expected that in the manufacture of wood products and urban furniture, the joints will be less affected by changes in weather conditions. This product also has a higher thermal stability than solid wood, which makes its use safer in cases exposed to higher temperatures.