| 초록 |
During cooling, silica, the archetype glass-former gradually increases its viscosity over a wide temperature range. Silica is not soluble. In striking contrast, all organic and polymer glass forming liquids increase their viscosity and rigidify abruptly when cooled and are soluble. In 2011 we introduced the concept and synthesized, vitrimers, polymer materials that undergo gradual glass transition like silica. Vitrimers are polymer networks that are able to change their topology without changing the total number of bonds through thermo-activated catalytically controlled exchange reactions. Solid at low temperatures and malleable when heated yet insoluble whatever the temperature, vitrimers constitute the third class of polymers along with thermoplastics and thermosets (elastomers). First vitrimers were made from epoxy resins, today many ingredients and chemistries used to obtain classical plastics and rubbers have been adapted to synthesize vitrimers. Since they can be shaped, assembled, repaired and recycled just like the glass, besides opening intriguing perspectives in both physics and chemistry, vitrimers should rapidly find applications in automotive, electronics, airplane, and coatings industries. |
