Asymmetric linker-mediated vitrimers

• Main Author: Zeng, Wu
• Other Authors: Ni Ran
• Format: Thesis-Master by Research
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Chemical engineering
• Online Access: https://hdl.handle.net/10356/163610
• Institution: Nanyang Technological University

Plastic is closely related to human daily life, which normally can be divided into thermoset and thermoplastic. One of the most important features of thermoset polymers is that they must be shaped (reaction) in a mold which fixes their shape to our design. The main reason for this is that once the reaction has been completed in the mold, the polymer can not be processed anymore by heat. This means the reaction is irreversible and it can only soften and flow when it is heated for the first time. In contrast, because of these weak intermolecular interactions, thermo- plastics can be easier to process by melting and remould by heating. However the mechanical stability is not good enough and the viscosity abruptly increases in a narrow temperature range when temperature is lowered below the glass transition. So a new smart material is an emergency need for this demand. Vitrimer, the prospective smart material, was created to handle these problems perfectly with the reversible networks that can flow while maintaining their me- chanical stability and insolubility at high temperatures. With the development of the first and second generation of vitrimer, a lot of problems have been solved in order to meet industry demand. Recently, the new concept of the thermo-gelling vitrimer have gained worldwide attention from traditional materials to biomaterials and biomedical. The application of thermo-gels have a large marketing prospect. The main mechanism of thermo-gelling vitrimers involves weak intermolecular interactions, such as hydrogen bonding, Coulombic and van der Waals interactions. One simple and accessible approach to outbalance the solvent effect between intra- and intermolecular interactions is to increase the temperature. As result, the thermo-gelling of the materials occurs. However, the weak non-covalent interaction usually leads to low mechanical stability and rapid disintegrations inphysiological environments. Here, we proposed asymmetric linker-mediated vitrimers. It may overcome those challenges is that permanently crosslinked gelling networks with higher mechanical stability and controlling the phase behaviour and equilibrium at high temperatures.