“Glamorous polymer” experiment
How to make a polymer from a resorcinol-formaldehyde solution
Practically all of the substances around us are polymers These substances are used in machine building, the textile industry, agriculture, medicine, automobile and ship building and aircraft construction. Polymers are also used in everyday life, and are contained in textile and leather items, crockery, glue and varnishes, jewelry and other items.
On the basis of high molecular compounds, rubbers, fibers, plastics, films, paints and coatings are made. Polymers are obtained by the reaction of polymerization – the reaction of the formation of a high molecular compound (a polymer) through the gradual attachment of molecules of a low molecular substance (a monomer). In our next experiment, we will show how the reaction of the polymerization of resorcinol and formaldehyde in an acidic medium takes place.
Wear rubber gloves and protective glasses when conducting the experiment, as concentrated hydrochloric acid causes burns. Formaldehyde and resorcinol are toxic and carcinogenic substances – work with a fume hood or in a well-ventilated room.
Warning! Do not try this at home. Only under professional supervision.
Reagents and equipment:
- 10% resorcinol solution;
- 35% formaldehyde solution;
- 35% hydrochloric acid;
The resorcinol and formaldehyde solutions are poured into a beaker. Then a few drops of concentrated hydrochloric acid are added, and the pale pink flakes of the polymer precipitate. In a few minutes, the hydrochloric acid becomes evenly distributed around the test tube, and the entire solution polymerizes to a red-pink solid polymer.
When concentrated hydrochloric acid is added to a solution of resorcinol and formaldehyde, a polymerization reaction starts, in which the molecules of resorcinol and formaldehyde bond and form the long chain of a polymer.
C₆H₆O₂ + CH₂O + HCl → H-[СН₂-C₆H₄O₂]ₙ-C₆H₅O₂