Tetraphenyladamantane-based microporous polyaminals for efficient adsorption of CO2, H2 and organic vapors

Abstract Herein, a new tetraphenyladamantane-cored triazine-based multiamine (TPADT) was designed and synthesized. Its bulky molecular volume, strong rigidity, and high amine functionality enable it easy to prop up the polymer backbone and form a high hypercrosslinking degree to obtain high microporosity. A series of highly microporous tetraphenyladamantane-based polyaminals (Ad-MALPs) were prepared through the catalyst-free copolymerization of TPADT and commercial aromatic aldehydes. By changing the strut length and functionality of aldehyde monomers, the resulting polymers exhibit tailored BET surface area (1541–1779 m2/g) and narrow ultramicropore size distribution (0.52–0.93 nm). Ad-MALP-2 with the largest microporosity possesses the highest CO2 uptake (21.1 wt %, 273 K/1.0 bar) and CO2/N2 adsorption selectivity (35.2). Interestingly, Ad-MALP-3 shows the highest H2 uptake (2.26 wt%, 77 K/1.0 bar) due to larger total pore volume. In addition, highly microporous Ad-MALPs simultaneously contain aromatic and cycloaliphatic components, and thus show exceptionally large aromatic and cycloaliphatic organic vapor adsorption capacity under low pressure. At P/P0 = 0.1, the benzene and cyclohexane vapor uptakes of Ad-MALPs are up to 44.8 wt% and 39.0 wt %, far exceeding that of most previously reported porous organic polymers. Considering that Ad-MALPs have outstanding gas adsorption performance, simple preparation, good stability, and cycle ability, they are expected to be promising adsorbent materials for CO2 adsorption/separation, H2 storage and low-concentration volatile organic vapors capture.