Polymers: Linking things together!

Today students had a fun chemistry lesson on polymers. The students learned all about natural and synthetic polymers and how they are found in food, fabrics, plastics, and even in our own bodies!  But exactly what is a polymer, you might ask? Polymers are a type of molecule made of linked chains of individual units, called monomers. Students learned that monomers form chains to create polymers, and that chains of polymers can be cross-linked together to make materials with different properties, like density, tensile strength, and elasticity.

After learning about the polymers that are all around us, students were then able to experiment with some cross-linking polymers themselves. We took a synthetic polymer (white school glue, which is called polyvinyl acetate) and mixed it with a cross-link solution, tetrahydroxyborate (Borax) in water. The result was dramatic! The slimy, sticky glue changed into a rubbery, dry substance that could be stretched, formed into a ball, broken sharply apart, and bounced. Your students should be able to tell you why cross-linking the polymer had this effect!

The students were very enthusiastic about making more of this polymer at home.  Here’s a recipe that you can follow.

Materials:

  • Elmers Glue (8 oz bottle of Elmers Glue-All)
  • Borax (a powdered laundry booster found in the grocery store)
  • Large mixing bowl
  • Plastic cup (8 oz size)
  • Spoon
  • Measuring cup
  • Food coloring (optional;)
  • Water
  • Zip-lock bag (to store it when you are done)
  1. Empty the entire bottle of glue (8 oz) into a mixing bowl. Fill the empty glue bottle with warm water, put the cap back on and shake. Pour the glue-water mixture into the mixing bowl and use the spoon to mix well.
  2. Add a drop or two of food coloring. (Not too much, it can stain)
  3. Measure 1/2 cup of warm water into the plastic cup and add a teaspoon of Borax powder to the water. Stir the solution – don’t worry if all of the powder dissolves. The Borax solution is the cross-linking agent.
  4. While stirring the glue in the mixing bowl, slowly add a little of the Borax solution. Immediately you’ll feel the long strands of molecules starting to connect. Put down the spoon and use your hands to do the serious mixing. Keep adding the Borax solution and mixing until you get a perfect batch of cross-linked polymer.
  5. When you’re finished playing with your polymer, seal it up in a zipper-lock bag for safe keeping.

Polímeros: ¡entrelazando cosas!

Hoy los estudiantes tuvieron una clase de química muy entretenida sobre  polímeros y aprendieron la importancia de éstos en nuestra vida. El almidón (papas, pasta), la celulosa (madera, plantas), el plástico, las telas tanto naturales (algodón, lana) como manufacturadas (rayón y nylon) y las proteínas, son todos ejemplos de polímeros. Pero, ¿qué es un polímero? Los polímeros son un tipo de moléculas compuestas por cadenas de unidades individuales llamadas “monómeros”. En esta clase, los alumnos aprendieron que los monómeros forman cadenas para crear polímeros, los cuales a su vez, pueden unirse entre sí para crear materiales que poseen diferentes características, como densidad, resistencia y elasticidad.

Después que los estudiantes comprendieron que estamos rodeados por polímeros, tuvieron la oportunidad de experimentar con polímeros que ellos mismos crearon.

Para la actividad, tomamos un polímero ya existente (pegamento o cola fría blanca o también conocido como acetato de polivinilo) y lo mezclamos con una solución de “entrecruzamiento” (cross-linking), llamada tetrahidroxiborato (Bórax) en agua.

¡El resultado fue impresionante! El pegamento que antes era pegajoso se transformó en una sustancia seca y como de goma, la cual podía ser estirada, podía moldearse en una pelota, se podía romper y además rebotaba. Sus hijos o hijas deberían ser capaces de explicarles por qué ocurrió este fenómeno al añadir la solución de entrecruzamiento.

 

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Categories
Open 7 days INFO
Our Young Pre classroom is for ages. This age group is working
BELL SCHEDULE