Synthesis, characterization, thermal stability, and application of microporous hyper cross-linked polyphosphazenes with naphthylamine group for CO2 uptake

There are numerous problems in the world, but environmental pollution is the biggest threat to life. Air pollution is the most critical form of environmental pollution because air is the most essential need of life. However, industrialization, population growth, and fossil fuel use increase hazardous and greenhouse gas concentrations daily. Greenhouse gases like carbon dioxide (CO2) contribute to global warming; hence, efficient, inexpensive, sustainable, and ecologically friendly air purification solutions are required. This study proposed a new method for synthesizing N- and P-rich polyphosphazene-based hyper cross-linked polymer (HCP) for CO2 adsorption. Due to their persistent porosity, low density, and high surface area, hyper cross-linked porous organic–inorganic hybrid phosphorus and nitrogen-rich polymers are cost-effective and promising gas adsorption materials. We synthesized hybrid organic and inorganic polyphosphazenes with nitrogen and phosphorus backbones and aromatic side groups cross-linked by the Friedel–Crafts alkylation process. HCP-A and HCP-B were cross-linked phosphazene-based microporous hybrid organic–inorganic polymers. HCP-A and HCP-B were produced in two stages. Hexachlorocyclotriphosphazene reacts with 1-napthylamine to form naphthyl amino phosphazene, which is cross-linked under optimum conditions to make cyclic HCP-A. Phosphorous dichlorophosphazene reacts with 1-naphthylamine to form poly[bis(1-naphthylamino) phosphazene] and is cross-linked to form linear HCP-B. HCP-A and HCP-B porous networks were studied with Brunauer–Emmett–Teller surface areas of 170.89 and 492.03 m2 g−1 and narrow pore sizes of 0.8–1.18 nm. These polymers are promising CO2 adsorbents due to their easy and cost-effective production, thermal stability, surface area, and CO2 absorption capacity.