Calix[4]arene-decorated polymers of intrinsic microporosity for lithium isotopes separation

Due to the importance of lithium isotopes in the nuclear energy industry, there are increasing number of researchs on the lithium isotopes separation in recent years. However, the adsorbents used for lithium isotopes separation suffer from the low adsorption capacity and isotopes separation factor in aqueous phase, and is difficult to meet the requirements for industrial lithium isotopes production. In this work, two types of calix[4]arenes with different rim groups were incorporated into the polymer backbone. Both calix[4]arene decorated PIMs exhibited good lithium adsorption capacities in aqueous phase. Among them, 4-tert-butyl-calix[4]arene decorated PIM showed excellent lithium isotopes separation performance with a maximum lithium adsorption capacity of 67.99 mg·g⁻¹ and an isotopes separation factor of 1.034 ± 0.003 in aqueous phase. The ease of preparing and stable cycling performance makes it potentially useful for industrial lithium isotopes production.