On July 16th, it was hard and brittle at room temperature, soft and elastic after heating, and "just" and "soft" can circulate back and forth with temperature changes. Associate Professor Li Chenghui from the School of Chemistry and Chemical Engineering of Nanjing University has developed a new polymer material that is “rigid and flexible”. The research results have been published in the journal Nature Communication.
”The biggest breakthrough of this material is to solve the problem of balance between mechanical strength and self-repair performance.” Li Chenghui introduced that the strength of the new material can change more than 200 times during the temperature change from room temperature to 60 ° C. Above 50 ° C, the properties of the material are similar to those of plasticine. This feature is due to the excellent temperature sensitivity of the new material. That is to say, the properties of the material can vary according to temperature changes, so researchers can control the properties of the material by changing the temperature.
"In daily life, we often see the melting of ice, the melting of candles, etc., but they will lose their original shape after the change." Li Chenghui said, while the new material is still solid after heating and softening, can withstand its own weight, can also Free shaping.
According to Li Chenghui, the reason why the new material has excellent temperature sensitivity is due to the existence of a large number of weak coordination bonds. The research team designed a short-chain polymethylsiloxane monomer with a large number of carboxyl groups in its side chain, which was crosslinked with weak coordination bonds formed by metal zinc to obtain a polymer material with very high mechanical strength. At the same time, since the coordination equilibrium reaction between the metal zinc and the carboxylic acid is temperature controlled, the material has good thermoplasticity and heat repairability.
New materials are expected to be well used in medical external fixation and 3D printing. For example, traditional plasters used in fracture treatments cure for up to several hours, while new materials can be shaped in minutes and can be easily removed and installed during use. In addition, traditional plaster is disposable and new materials can be recycled.