Effects of droplet size and solute concentration on drying process of polymer solution droplets deposited on homogeneous surfaces

On the lifetimes of evaporating droplets with related initial and receding contact angles

“…Note that in the special case of an ideal substrate with no pinning force, i.e., in the special case F p = 0, Equation (8) reduces to the well-known Young-Laplace equation for θ = θ 0 . As the droplet continues to evaporate, θ decreases and hence F p increases until it reaches its maximum possible value, denoted by F p max , when θ = θ * , at which instant the contact line depins and subsequently the droplet evaporates in a CA phase with θ = θ * constant and R decreasing.…”

“…[6][7][8][9][10][11][12][13][14] is one in which an initial stick phase is followed by a first slide phase with constant contact angle and a second slide phase in which both the contact radius and the contact angle vary. In practice, the second slide phase can be relatively short compared to the other two phases, and so Nguyen and Nguyen, 15 Dash and Garimella, 14 and Stauber et al 16 considered a simple but effective model for an idealised SS mode in which the second slide phase is entirely neglected and initially the droplet evaporates in a CR phase in which R = R 0 and θ(t) and V (t) decrease until θ(t) reaches the receding contact angle θ * (0 ≤ θ * ≤ θ 0 ), at which the contact line depins and subsequently the droplet evaporates in a CA phase in which θ(t) = θ * and R(t) and V (t) decrease to zero at time t = t SS , where t SS (which depends on both θ 0 and θ * ) denotes the lifetime of the droplet.…”

Imaging internal flows in a drying sessile polymer dispersion drop using Spectral Radar Optical Coherence Tomography (SR-OCT)

“…In their work, they introduce a numerical model which is confirmed by the experiments of Morozumi et al [4] and Park et al [5] using very small (∼50µm) droplets, similar to those used in ink jet printing. Fukai et al [6] investigated the evaporation process of water-xylene-polystrene droplets and concluded that the pinning time or the receding distance are important factors to determine the shape and dimension of the final shape. Moreover the results of Hu and Larson [7] revealed that the coffee-ring phenomena not only requires a high evaporation rate near the pinned contact line but also suppression of Marangoni flow.…”

Surface Energy-Modulated Inkjet Printing of Semiconductors

“…However, for the printing of organic semiconductors, it is still difficult to set up an accurate model for the evaporation process based on the contact angle hysteresis measured by a classical method. Because the contact angle, pinning diameter and receding distance are found to be dependent on various factors such as droplet size, solute concentration, and the contact line velocity [11]. It is observed that the receding contact angle determines the TCL behaviors, and can be successfully employed for the assembling of photonic crystals into a dome structure [12].…”