A simple but effective method for the synthesis and preparation of epoxy resin based controllable negative thermal expansion organic composites was developed. We synthesized polyamide with eight-membered carbon ring structure and introduced it into epoxy resin crosslinking network by solvent assisted method to modify epoxy resin. It makes up for the defects of traditional epoxy resin with high thermal expansion coefficient and strong brittleness, and overcomes the problems of weak interfacial connectivity and low crosslinking degree existing in inorganic NTE materials. Nano TiO2 ultrasonic dispersion combined with modified epoxy resin material can achieve comprehensive improvement of thermal stability and mechanical properties of the composite material, and solve the problem of positive expansion of the material at low temperature due to low polyamide content.

The synthesis of eight-membered cyclic polyamide was characterized by carbon, hydrogen, infrared and mass spectrometry. The surface and section morphology of modified epoxy materials were studied by scanning electron microscopy (SEM). The molecular dynamics simulation of the system was carried out, the cross-linking of polymers and the total energy of the system were calculated, and the swelling rate of the composite was studied by means of swelling equilibrium method. The thermal and mechanical properties of the composites were evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and electronic universal testing machine. The results show that with the increase of polyamide proportion, the characteristic peak does not change, the crack order gradually deteriorates, the flexibility increases, the NMP swelling rate increases, and the thermal stability increases.