An organo-main group network solid having tetrahedral phosphonium vertices was prepared from a diacetyl monomer via a straightforward cyclotrimerization reaction. The network solid composition was examined by FT-IR spectroscopy and elemental microanalysis, revealing quantitative reaction of carbonyl moieties and a 67% degree of cross-linking. The reaction yielded a material having a layered structure that is comprised of an amorphous polymer and which is thermally stable up to 370 degrees C in air with a char yield of 40% upon heating as high as 800 degrees C under N-2. The polymer is stable to 6 M Na-OH( aq) at 60 degrees C for 24 h and takes up only 10.63% of water by mass at room temperature. The surface morphology, as examined by AFM, revealed a very smooth as-prepared film (RMS roughness of 3 nm). The specific surface area measured by BET analysis with N2 gas is 9 m(2) g(-1) ,indicating a type II, nonporous material. Physisorption with CO2 revealed that the phosphonium network solid has additional affinity for CO2, suggesting that such materials may have use for applications such as CO2 capture. (C) 2017 Wiley Periodicals, Inc.