The objective of this activity is to demonstrate the use of polymers and one of their multiple properties from an informative point of view and with daily use materials. The philosophy of the demonstration is to illustrate how important crystallisation processes are to understand the physics of materials.

1) The objective of this activity is to demonstrate the use of polymers and one of their multiple properties from an informative point of view and with daily use materials.

The activity consists of preparing a cross-linked polymer (slime), based on daily use elements such as transparent glue, water and borax. In addition, food colouring is used to colour the polymer and a few drops of fluorescein (organic fluorophore) can be added to give it emissive properties after illumination with ultraviolet light.

Polyvinyl alcohol (PVA), a component of transparent glue, is soluble in water. However, when mixed with borax it forms a three-dimensional network that traps water creating a semi-solid gel known as “slime”.

2) The philosophy of the demonstration is to illustrate how important crystallisation processes are to understand the physics of materials.

In this activity we explain the instantaneous crystallisation of sodium acetate from a supersaturated solution, that is, solutions that contain quantities of dissolved solute exceeding the limit that the solvent is capable of admitting.

When these solutions come into contact with a crystallisation nucleus such as a rod or a sodium acetate crystal, they immediately crystallise exothermically (with the release of energy, in this case heat), with which massive crystals are obtained instantly.

It is also intended to show the phenomenon of fluorescence by including small amounts of a fluorescent organic compound such as fluorescein in the solutions.

Thus, under UV radiation, the crystal formed from Sodium Acetate emits an intense green light that resembles a kryptonite crystal.

Coordinated by: 1) Raquel Galián and Alejandra Soriano, Researchers at the Molecular Science Institute of the University of Valencia; 2) Efrén Navarro Moratalla, Jaume Meseguer, Filippo Mione, Ivona Kosic, José Joaquín Perez, Dra. Marta Galbiati, Fernando Cantos and Antonio Monteagudo, Researchers of the Molecular Science Institute of the University of Valencia.

Date and time:
September 30, 2022, from 10 am to 14 pm and from 17 pm to 21 pm

Place: Principe Felipe Science Museum