Accelerating Membrane‐based CO₂ Separation by Soluble Nanoporous Polymer Networks Produced by Mechanochemical Oxidative Coupling

Abstract

Achievingh omogeneous dispersion of nanoporous fillers within membrane architectures remains agreat challenge for mixed-matrix membrane (MMMs) technology.I mparting solution processability of nanoporous materials would help advance the development of MMMs for membrane-based gas separations.Amechanochemicallyassisted oxidative coupling polymerization strategy was used to create an ew family of soluble nanoporous polymer networks.T he solid-state ballmilling method affords inherent molecular weight control over polymer growth and therefore provides unexpected solubility for the resulting nanoporous frameworks.M MM-based CO 2 / CH 4 separation performance was significantly accelerated by these new soluble fillers.W ea nticipate this facile method will facilitate new possibilities for the rational design and synthesis of soluble nanoporous polymer networks and promote their applications in membrane-based gas separations.The interest in curtailing greenhouse gas emissions through capture of CO 2 from flue gas and removal of CO 2 from synthesis gas (mainly CH 4 and H 2 )h as inspired an extensive search for novel methods capable of efficient separation of CO 2 . [1] Membrane-based CO 2 separation technology has gained significant attention as ap romising solution, owing to its lower energy costs and reduced environmental impact. [2] Among the various types of CO 2 -selective membranes, polymeric membranes have been the most widely studied, whereas they suffer from awell-known compromise between the permeability and selectivity as shown in the upper bound Robeson curves. [3] Coupling polymer matrices with nanoporous filler particles,f or example nanoporous organic networks (NPNs), could lead to synergistic improvements in membrane-based CO 2 separation performance,b ut difficulties are encountered in achieving homogeneous dispersion of these nanoporous fillers within MMMs. [4] Although significant progress has been made in the synthesis of NPNs by linking multidentate organic scaffolds towards aw ide variety of potential applications, [5] it remains ag reat challenge to fabricate soluble nanoporous organic networks (SNPNs) through ar apid and straightforward method, mainly because it is very difficult to control the growth of polymeric architectures. [6] Ladder-like polymers of intrinsic microporosity (PIMs) with contorted sites have been reported as afamily of soluble porous polymers and successfully utilized in membrane-based gas separations. [7] Recently, Cooper el al. pioneered another successful synthesis of soluble porous polymer using ah yperbranching-based approach based on Suzuki-catalyzed aryl-aryl coupling copolymerization. [6a] Theo bvious downside is the use of the costly Pd-containing catalyst and necessity of complicated organic synthetic processes,significantly limiting the potential for practical implementation. In this regard, the search for novel techniques that are capable of efficient and facile synthesis of SNPNs is of great interest, importance,a nd urgency. Imparting solution processability woul...

The mechanochemical synthesis of polymers

“…to 5 eq. A similar result was obtained when the same group advanced this protocol to soluble nanoporous networks, 265 starting from a ladder-like monomer structure (3,3,3 0 ,3 0 -tetramethyl-2,2 0 ,3,3 0 -tetrahydro-1,1 0 -spirobi[indene]-6,6 0 -diol) (Fig. 16).…”

Surpassing Robeson Upper Limit for CO2/N2 Separation with Fluorinated Carbon Molecular Sieve Membranes

“…13 Intensive research efforts have been devoted to the rational design and preparation of novel nanoporous polymeric materials to overcome this limit, for example, by using thermally rearranged (TR) polymers, 14 polymers of intrinsic microporosity (PIMs), 15,16 and mixed-matrix membranes (MMMs). 6,17 The most significant feature in most of these approaches is the addition of entropic selectivity to improve molecular discrimination between similarly sized gas molecules. 18 The Bigger Picture Rational design of robust and highly selective separation processes leading to an efficient sequestration of anthropogenic CO 2 is one of the most important problems, especially considering the effects of climate change.…”

Mechanochemical Synthesis of High Entropy Oxide Materials under Ambient Conditions: Dispersion of Catalysts via Entropy Maximization

“…6,7 Mechanochemical synthesis (MS) has shown promising performance in the rapid roomtemperature synthesis of porous metal−organic frameworks (MOF), 8−12 covalent organic frameworks (COF), 13 and porous organic polymers. 14 Beyond porous materials synthesis, ball milling has been used to promote catalysis of C−H bond functionalization/amination 15,16 and in the generation of Baylis−Hillman products. 17 More relevant to our work, MS has been used in the synthesis of perovskite materials (ABO 3 ), which would normally require 800−1200 °C.…”