Study On Melamine And Isonicotinic Acid Two Component Supramolecular Gel And Its Derivatives

Supramolecular hydrogel is a type of excellent soft materials.It is self-assembled by small molecules through non covalent interactions,forming a tangled nanostructure,with superior flexibility,reversibility and biocompatibility.In general,supramolecular hydrogel can be divided into single component hydrogel and multi component hydrogel,which greatly enriched the formation of new structures at different levels.Aerogels are well-known flexible materials,which are obtained by replacing the liquid in gel with gas while maintaining the three-dimensional network structure.Although several aerogels have been achieved from supramolecular organic gel,to the best of our knowledge,the preparation of supramolecular aerogels from hydrogels has not been reported.Carbon aerogels,as an important branch of aerogels,not only possess excellent mechanical and chemical properties as well as electrical conductivity of carbon materials,but also have a highly open three-dimensional network structure of porous gel.In order to obtain carbon aerogels with good pore structure,sacrificial template method is often used.In this work,we assembled supramolecular hydrogel with small organic molecules as raw materials,and then a functional supramolecular aerogel was achieved through simple freezedrying technology.Carbon fiber aerogels were derived from supramolecular gel as template and used for pressure sensing and wearability device.The paper mainly includes the following aspects:(1)Supramolecular hydrogels were prepared by self-assembly of small molecule melamine(M)and isonicotinic acid(IA),and then a functional supramolecular aerogel was obtained by simple freeze-drying technology.The obtained aerogel has ultra-low density,high porosity and no shrinkage or collapse occurred during the transformation of hydrogel into aerogel.Further,it displayed elasticity and strong fatigue resistance under weight loadingunloading cycles.In particular,we systematically studied the scaling law of elastic modulus and density for the first time,in order to prove that the supramolecular aerogels can maintain mechanical efficiency in a wide range of densities without obvious stiffness degradation.In addition,it was used as sound insulation materials,which exhibited good sound insulation performance and followed the law of mass sound transmission.Compared with the conventional polymer foam sound insulation materials,supramolecular aerogels have the characteristics of easy degradation and environmental friendliness,so they can act as ideal environmental protection functional materials in the future.(2)Using supramolecular gel as a template,carbon fiber aerogel was prepared,and its mechanical and electrical properties were studied in detail.Specifically,the supramolecular hydrogel was doped with initiator and acrylonitrile for photo-initiated polymerization.After freeze-drying,pyrolysis and carbonization,the carbon fiber aerogels were obtained.It exhibited good electrical conductivity and elastic properties.A pressure sensor was assembled using the carbon fiber aerogels as functional electrode.The investigation of performance found that the device showed instantaneous electrical signal changes with pressure changes and stable electrical signals under fixed pressure,and also displayed a sensitive and rapid response effect in human testing,which can be used as a promising wearable device.The thesis is based on the preparation and application of supramolecular gel materials,as well as the preparation and application of carbon fiber aerogels derived on this basis.