## 1 Introduction  
Poly(ionic liquid)-based membranes for CO\({}_{2}\) capture overcome the possible problems of ionic liquid (IL) leaching from the supported IL membranes [1]. However, poly(ionic-liquids) (PILs) demonstrate a considerable reduction of CO\({}_{2}\) sorption capacity and diffusion rates due to higher stiffness of the polymer matrix, leading to lower CO\({}_{2}\) transport [2; 3]. PIL matrix can be altered by incorporating additives that will disrupt the polymer chain packing, such as ILs and inorganic salts [4; 5]. Poly(ionic liquid)s (PILs) have recently prompted extensive practical aspirations due to their potential to combine the large CO\({}_{2}\) sorption capacity of ionic liquids (IL) and good processability of conventional polymers [6; 7; 8]. PIL synthesis so-far focused mainly on the development of tailor-made materials from polymerisable IL-monomers, offering excellent gas separation properties [9; 10; 11; 12]. The IL monomers should have a high degree of purity, and undergo elaborate synthetic procedures to produce large amounts of PILs with sufficient molecular chain length, which might present a critical factor in their further employment as selective membranes for CO\({}_{2}\) capture [13]. A more limited body of work explores the functionalization of conventional polymers used in membrane-based gas separation, such as cellulose acetate [14; 15; 16], poly(vinylbenzyl chloride) [17; 18], polybenzimidazole [19; 20; 21], polyurethane [22] and poly(diallyldimethyl chloride)(P[DADMA] [CI])[10; 13; 16; 23; 24; 25], as alternative substrates for PIL-like structures. In contrast to IL-monomer polymerization, this route proposes the direct incorporation of IL-moieties in the polymeric backbone and/or further ion exchange. As P[DADMA][CI] allows a simpler PIL or polyelectrolyte (PE) synthesis by only anion exchange, many existing studies focused on understanding the underlying phenomena connecting the physico-chemical-structural properties with performance evaluation, in which the group of Marucho plays a pivotal role [10; 13; 24; 25; 26; 27; 28; 29]. However, the P[DADMA][CI] PIL derivatives often demonstrate low mechanical strength and CO\({}_{2}\) sorption capacity [13; 28], requiring the conditioning of synthesised PILs with plasticizing agents or pure ILs that would act as a plasticiser for the rigid polymer chains. In this case, IL also acts as an additional sorption phase for permeating CO\({}_{2}\) molecules [11]. Additionally, the low viscosity of IL segments would allow faster gas transport due to enhanced diffusivity [30]. Several critical reviews report on the progress in PIL/IL composite material development [5; 6; 31]. Several PIL/IL composites excel and cross the Robeson plot for CO\({}_{2}\)/N\({}_{2}\) separation [2; 10; 26; 28; 32]. However, the majority of them exhibit moderate CO\({}_{2}\) permeabilities (10-300 Barrer) and CO\({}_{2}\)/N\({}_{2}\) selectivities (20-40) [28; 29]. Those are still far below the industrially relevant CO\({}_{2}\) permeance of 1000 GPU and CO\({}_{2}\) selectivity of at least 50 [33]. Moreover, while recent scientific reports underscore the improved separation performance of IL-based gas separation membranes in dry feed, real flue gas always contains water vapor, making the investigations in humidified conditions obligatory [17; 34; 35]. The PIL/IL composite's performance was further altered by the addition of copper salt to facilitate the CO\({}_{2}\) transport by [PERSON] et al. [4]. In the present work, zinc ions are introduced to investigate their influence on the performances of PIL/IL composites. In nature, Zn\({}^{2+}\) participates in the chemical binding of CO\({}_{2}\) molecules, as a structural component of more than 300 enzymes, with carbonic anhydrase being the most widely known example [36; 37; 38]. Zn\({}^{2+}\) is at the center of a catalytically active site with enhanced Lewis acidity in tetrahedral configuration, coordinating three ligands and a water molecule [39].