Sustainable In-Water Synthesis of Aliphatic Porous Polyazines: A Versatile Platform for Conjugated Aerogels, PolyHIPEs, or Carbon Foams

Access to conjugatedporous polymers via syntheticallysustainableand straightforward routes is highly desirable, as many polymer systemsexhibit high performance but require arduous synthetic protocols thatrarely pave the way to commercial reality. In this article, we describean easily fabricated series of novel highly porous poly(Schiff bases)that feature an aliphatic conjugated backbone obtained with low syntheticcomplexity from simple reagents such as glyoxal and hydrazine monohydratein water. The effective synthesis enables the preparation of threedifferent functional scaffolds, i.e., aerogels, polyHIPEs (polymerizedHIPEs), and even carbon foams from aliphatic poly(azine) (PAZ) networks.The reported synthetic approach is compared to the literature using & DPRIME;green chemistry metrics & DPRIME;, such as the E-factor and synthetic complexity (SC) index, and shows dramatic improvements.An E-factor of up to 0.27 for aerogels or 80 forpolyHIPEs and an SC index of 2.7 are much lower than those for poly(arylene)-basedconjugated analogues, indicating good scalability, sustainability,and low cost. PAZ materials feature impressive red/near IR-shiftedoptical absorption band edges, with an electrochemical band gap of1.45 eV. Aliphatic PAZ scaffolds are characterized by high flexibilitycompared to aromatic analogues and do not fail at compressive loadsof up to 70%. Finally, carbonization at 500 & DEG;C leads to highlyporous carbonaceous scaffolds with a high N content of up to 29 wt% (21 mmol of nitrogen per gram carbon material).