Post-modified homo-coupled conjugated microporous polymer hollow nanostructured spheres via click chemistry for thermal insulation materials with excellent flame retardancy

Abstract

The development of materials with both outstanding thermal insulation and excellent flame retardant properties has received considerable attention for preparation of energy-saving materials in construction industry. In this work, 1,3,5-Triethynylbenzene and 1,4-Diethynylbenzene were used as monomers to synthesize two kinds of homo-coupled conjugated microporous polymer hollow nanostructured spheres (HCMPs-NHS), followed by the post-modification of the HCMPs-NHS using diphenyl azide phosphate (DPPA) to react with end alkynyl group via "click chemistry" method (named as HCMPs-NHS-FR). The as-synthesized HCMP1-NHS-FR and HCMP2-NHS-FR have excellent thermal insulation performance, in which thermal conductivity is 0.049 W m−1 K−1 and 0.05 W m−1 K−1, respectively. The peak heat release rate (pHRR) from the microscale combustion colorimeter (MCC) of HCMPs-NHS-FR was 94.834 W/g and 70.799 W/g, respectively. To further explore the flame retardant properties, the HCMPs-NHS-FR was introduced into the epoxy resin (EP) to obtain EP-1 and EP-2, and it was found that pHRR from conical calorimetry (CC) was 496.38 KW/m2 and 596.96 KW/m2, respectively, which was lower than 30.4 % and 16.3 % compared with pure EP. Based on the advantages of superior thermal insulation and flame retardancy mentioned above, the as-synthesized HCMPs-NHS-FR may have enormous potential as flame retardant with good thermal insulation in the future building energy-saving.