Rational Design and Synthesis of Hybrid Porous Polymers Derived from Polyhedral Oligomeric Silsesquioxanes via Heck Coupling Reactions

Abstract

Heck coupling reactions are introduced as an efficient method to prepare porous polymers. Novel inorganic-organic hybrid porous polymers (HPPs) were constructed via Heck coupling reactions from cubic functional polyhedral oligomeric silsesquioxanes (POSS), iodinated octaphenylsilsesquioxanes (OPS) and octavinylsilsesquioxanes (OVS) using Pd(OAc)2 /PPh3 as the catalyst. Here, two iodinated OPS were used, IOPS and p-I8 OPS. IOPS was a mixture with 90% octasubstituted OPS (I8 ) and some nonasubstituted OPS (I9 ), while p-I8 OPS was a nearly pure compound with ≥99% I8 and ≥93% para-substitution. IOPS and p-I8 OPS reacted with OVS to produce the porous materials HPP-1 and HPP-2, which exhibited comparable specific surface areas with SBET of 418 ± 20 m(2) g(-1) and 382 ± 20 m(2) g(-1) , respectively, with total pore volumes of 0.28 ± 0.01 cm(3) g(-1) and 0.23 ± 0.01 cm(3) g(-1) , respectively. HPP-1 showed a broader pore size distribution and possessed a more significant contribution from the mesopores, when compared with HPP-2, thereby indicating that IOPS may induce more disorder because of the geometrical asymmetry. HPP-1 and HPP-2 possessed moderate carbon dioxide uptakes of 134 and 124 cm(3) g(-1) at 1 bar at 195 K, making them promising candidates for CO2 capture and storage. The synthesized porous polymers may be easily post-functionalized using the retained ethenylene groups.