The principle of the smoothie cup is that the polyvinyl alcohol and borax fully expanded in water are cross-linked to form a body-shaped structure, and then absorb a large amount of water to expand into a translucent and easy-flowing gel. The liquid in the smoothie cup is frozen liquid, which is mainly used for freezing. Put the inner cup into the freezer first, freeze it for more than 8 hours, then take it out, put it in the outer cup, and use a spoon to remove it. The thin layer of ice on the wall of the inner glass is scraped off, and after adding the juice or milkshake, it is ready to eat. This process only takes a few minutes.
Ice is a crystal formed by the orderly arrangement of water molecules, which are linked together by hydrogen bonds to form a very "open" (low density) rigid structure. The O—O internuclear distance of the nearest water molecule is 0.276 nm, and the O—O—O bond angle is about 109 degrees, which is very close to the bond angle of an ideal tetrahedron of 109 degrees and 28 minutes. But the O-O spacing of water molecules that are only adjacent but not directly combined is much larger, and the farthest one is 0.347 nm. Each water molecule can combine with 4 other water molecules to form a tetrahedral structure, so the coordination number of water molecules is 4.