Evaluating the impact of functional groups on membrane-mediated CO2/N2 gas separations using a common polymer backbone

Polymeric membranes have shown tremendous promise for the separation of CO₂ from flue gas streams. However, few systematic studies have been conducted to better understand the impact that chemical functionalities have on membrane-based gas separation performance. To address this gap, we herein describe the synthesis and gas separation performance of a series of vinyl-addition polynorbornenes bearing various CO₂-philic functional groups. To facilitate direct comparison between functional groups, each material was designed to maintain a common polymer backbone. Though the incorporation of CO₂-philic moieties within a dense polymeric membrane is frequently hypothesized to enhance CO₂ solubility, and thereby increase CO₂/N₂ selectivity, our results demonstrate that the incorporation of CO₂-philic groups onto a common polymer backbone do not necessarily result in increased gas separation performance. Experimental and computational results demonstrate that the incorporation of amidoxime groups onto a polynorbornene backbone increase CO₂/N₂ selectivity, whereas commonly employed ethereal side chains only increased permeability.     

Palladium complex with tetrahydronaphthyl-substituted diimine ligand as a catalyst for polymerization of norbornenes and diazoacetates

New methylpalladium chloride complex with bulky N,N'-bis(1,2,3,4-tetrahydro-1-naphthyl)-substituted glyoxal diimine ligand was obtained. This complex was found to be an efficient catalyst for vinyl-addition polymerization of norbornene derivative and for polymerization of a diazoacetate, giving polycarbenes with side polar functionalities.     

Nickel complexes bearing different electron groups on substituted salicylaldnaphthylmethyleneimine ligands: Syntheses and their catalytic performance for (co)polymerization of norbornene

Novel nickel complexes bearing different electron groups on substituted salicylaldnaphthylmethyleneimine ligands, bis-(salicylaldnaphthylmethyleneimino)Ni(II) (Ni{(3-R¹)(5-R²)C₆H₂(O)CH[N (naphthyl-CH₂)]}₂ Ni1 : R¹ = H, R² = H; Ni2 : R¹ = H, R² = CH₃; Ni3 : R¹ = H, R² = Br; Ni4 : R¹ = H, R² = OCH₃; Ni5 : R¹ = CH₃, R² = H; Ni6 : R¹ = Br, R² = H), were synthesized. Ni2 , Ni3 , Ni5 , and Ni6 are clearly characterized by single-crystal X-ray diffraction. Co-polymerization of norbornene (NB) with 5-norbornene-2-methylene butyl ether (BN) was carried out in toluene with the aforesaid complexes as catalyst precursors and B(C₆F₅)₃ as the co-catalyst. Catalyst activity, molecular weight, thermal stability, solubility, regularity, and optical transparency were investigated, and the mechanism of the electron groups changing catalyst performance is explained. All catalysts show high activity toward co-polymerization (up to 3.53 × 10⁵ g_polymer mol_Ni⁻¹ h⁻¹). Ni3 shows the highest activity and Ni5 shows the highest insertion rate (up to 37.6%). The obtained poly(NB-co-BN)s are confirmed to be vinyl-addition-type co-polymers, and they are noncrystalline. The co-polymers exhibited excellent thermal stability and processability (T_d ≥ 400 °C, T_g < 240 °C), optical transparency (up to 90%), and good solubility.