Apparatus and method for testing solid-liquid dynamic and static contact angles by actual liquid droplet method

Abstract

The invention discloses an apparatus and a method for testing solid-liquid dynamic and static contact angles by an actual liquid droplet method. The method comprises the following steps of: during the testing, placing a solid phase sample on a sample table; controlling X, Y and Z of the sample table to move to a focusing position of a lens; sucking the liquid phase sample into a micro sample injector, injection pump or peristaltic pump; controlling the X, Y and Z of the sample injector to move to the focusing position; dripping a small droplet of the liquid and adsorbing the droplet to a needle head; moving the needle head to the surface of the solid phase sample until the liquid phase sample is adsorbed to the surface of the solid; making a software system control an optical imaging system (CCD) to capture a real-time picture and analyzing the picture by using the actual liquid droplet method; and displaying calculated solid-liquid contact angle value, solid surface free energy value and adhesion work value and managing the values by a database. The apparatus and the method can completely improve the accuracy of the analysis of the solid-liquid interfacial tension, are simple to operate, can be widely applied and have high popularization value.

Description

technical field [0001] The invention relates to an instrument and a detection method for testing a contact angle, more specifically, an instrument and a method for testing a solid-liquid dynamic and static contact angle by a real droplet method. Background technique [0002] Basic indicators such as liquid-liquid interfacial tension, liquid-gas surface tension, and solid-liquid contact angle are basic parameters that characterize the physical and chemical properties of a substance. At the solid-liquid-gas three-phase junction point above, the angle formed when the two tangent lines of the gas-liquid interface and the solid-liquid interface sandwich the liquid phase, the contact angle test is to analyze the physical and chemical properties of the solid-liquid interface The most important means, currently widely used test methods include weighing method and optical image analysis method. [0003] Traditional contact angle measurement methods, including those provided by measu...

AI Technical Summary

Problems solved by technology

[0003] Traditional contact angle measurement methods, including those provided by measuring instruments on the market and used in academic and research fields, almost all assume the contour of the droplet, except for the tangent method based on polynomial or B-Spline curves (Note). Conforms to a certain mathematical model, and is based on the premise of an axisymmetric mathematical model. Although the generalized quadratic curve method provided by the DropMeter software allows the drop to appear asymmetrical, the mathematical model itself is still axisymmetric. The droplet is actually only a part of this axisymmetric model. Under such a model, not only the outlines of the left and right sides of the droplet are coupled together as a whole, but also the contact angles of the two sides influence each other. In fact, the droplet is usually asymmetrical. Although the outline of the droplet is related to each other as a whole, its contact angle is not the same everywhere along the three-phase contact line. The contact angle of the left and right sides of the droplet section does not have to be are closely related, and in more cases, they are affected by the local environment in which they display different values, especially when the droplet is affected by another external object such as a needle (such as measuring forward / backward by the droplet enlargement / shrinkage method Contact angle) interference, the contours of the left and right sides can also be relatively independent, and the correlation is weak. Based on these characteristics of real droplets, these traditional axisymmetric models are used to fit the obtained droplets to calculate the contact angle. The value of , in fact, is a bit reluctant in most cases, the model can not fit the actual data very well, resulting in a deviation from the actual real value, and the size of the deviation depends on the model used and the actual data (droplet shape) Degree of conformity: the worse the degree of conformity, the greater the deviation

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