"Polymerization" experiment

How to make a polymer using resorcinol and formaldehyde

Did you know that prac­ti­cal­ly all of the sub­stances around us are poly­mers? Thanks to their valu­able prop­er­ties, poly­mers are used in ma­chine build­ing, the tex­tile in­dus­try, agri­cul­ture, medicine, au­to­mo­bile and ship build­ing, air­craft con­struc­tion and ev­ery­day life (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.

Reagents and equip­ment:

  • re­sor­ci­nol (10 g);
  • formalde­hyde (10 ml);
  • con­cen­trat­ed hy­drochlo­ric acid (10 ml);
  • dis­tilled wa­ter, test tube.

Step-by-step in­struc­tions

Pour 25 ml of an aque­ous so­lu­tion of re­sor­ci­nol and 10 ml of formalde­hyde into a test tube. Then add a few drops of con­cen­trat­ed hy­drochlo­ric acid, and ob­serve the pre­cip­i­ta­tion of the pale pink flakes of the poly­mer. In a few min­utes, the hy­drochlo­ric acid be­comes even­ly dis­trib­uted around the test tube, and the en­tire so­lu­tion poly­mer­izes to the for­ma­tion of a red-pink sol­id poly­mer.

Pro­cess­es de­scrip­tion

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 be­gin to bond and form the long chain of a poly­mer.

This poly­mer­iza­tion re­ac­tion was pre­vi­ous­ly used in den­tistry as a method for treat­ing root canals, but af­ter a num­ber of po­ten­tial com­pli­ca­tions were dis­cov­ered, safer treat­ment meth­ods were found.

Safe­ty pre­cau­tions

In work­ing with con­cen­trat­ed hy­drochlo­ric acid, wear rub­ber gloves and pro­tec­tive glass­es, as it caus­es burns if it comes into con­tact with the eyes and skin. Con­duct the ex­per­i­ment in a fume hood or in a well-ven­ti­lat­ed room. Dan­ger­ous sub­stances are used in the ex­per­i­ment, such as formalde­hyde and re­sor­ci­nol, which are tox­ic car­cino­gens.

Warn­ing! Sub­stances of this ex­per­i­ment are tox­ic and high­ly dan­ger­ous for your health. Do not try this at home. Only un­der pro­fes­sion­al su­per­vi­sion.

Try it