Layer-by-layer (LbL) assembly of the alternating adsorption of oppositely charged polyions is an extensively studied method to produce nanofiltration membranes. In this work, the concept of chaotropicity of the polycation and its counterion is introduced in the LbL field. In general, the more chaotropic a polyion, the lower its effective charge, charge availability, and hydrophilicity. Here, this is researched for the well-known PDADMAC (polydiallyldimethylammonium chloride) and PAH (poly(allylamine) hydrochloride), and the synthesized PAMA (polyallylmultimethylammonium), with two different counterions (I- and Cl-). Higher chaotropicity (PDADMAC > PAMA-I > PAMA-Cl > PAH) translates into a reduced charge availability and a more pronounced extrinsic charge compensation, resulting in more mass adsorption and a higher pure water permeability. PAMA-containing membranes show the most interesting results in the series. Due to its molecular structure, the chaotropicity of this polycation perfectly lies between PDADMAC and PAH. Overall, the chaotropicity of PAMA membranes allows for the formation of the right balance between extrinsic and intrinsic charge compensation with PSS. Moreover, modifying the nature of the counterions of PAMA (I- or Cl-) allows to tune the density of the multilayer and results in lower size exclusion abilities with PAMA-I compared to PAMA-Cl (higher MWCO and lower MgSO4 retention). In general, the contextualization of the polyion interaction within the specific (poly)ion effects expands the understanding of the influence of the charge density of polycations without ignoring the chemical nature of the functional groups in their monomer units.
Organic ionic plastic crystals (OIPCs) are a class of soft materials showing positional order while still allowing orientational freedom. Due to their motional freedom in the solid state, they possess plasticity, non‐flammability and high ionic conductivity. OIPC behavior is typically exhibited by ‘simple’ globular molecules allowing molecular rotation, whereas the interactions that govern the formation of OIPC phases in complex non‐globular molecules are less understood. To better understand these interactions, a new family of non‐globular OIPCs containing a 15‐crown‐5 ether moiety was synthetized and characterized. The 15C5BA molecule prepared does not exhibit the sought‐after behavior because of its non‐globular nature and strong intermolecular H‐bonds that restrict orientational motion. However, the OIPC behavior was successfully obtained through complexation of the crown‐ether moiety with sodium salts containing chaotropic anions. Those anions weaken the interactions between the molecules, allowing rotational freedom and tuning of the thermal and morphological properties of the OIPC.
The pervasive use of screens, averaging nearly 7 hours per day globally across mobile phones, computers, notebooks and TVs, has sparked a growing desire to minimize reflections from ambient lighting and enhance readability in harsh lighting conditions, without the need to increase screen brightness. This demand highlights a significant need for advanced anti-glare (AG) technologies, to increase comfort and eventually reduce energy consumption of the devices. Currently used production technologies are limited in their texture designs, which can lead to suboptimal performance of the anti-glare texture. To overcome this design limitation and improve performance of the anti-glare feature, this work reports a new, cost-effective high-volume production method that enables the much needed design freedom on a large area. This is achieved by combining mastering via large-area Laser Beam Lithography (LBL) and replication by Nanoimprint Lithography (NIL) processes. The environmental impact of the production method, such as material consumption, are considered and the full cycle from design to final imprint is discussed.
The pervasive use of screens, averaging nearly 7 h per day globally between mobile phones, computers, notebooks and TVs, has sparked a growing desire to minimize reflections from ambient lighting and enhance readability in harsh lighting conditions, without the need to increase screen brightness. This demand highlights a significant need for advanced anti-glare (AG) technologies, to increase comfort and eventually reduce energy consumption of the devices. Currently used production technologies are limited in their texture designs, which can lead to suboptimal performance of the anti-glare texture. To overcome this design limitation and improve the performance of the anti-glare feature, this work reports a new, cost-effective, high-volume production method that enables much needed design freedom over a large area. This is achieved by combining mastering via large-area Laser Beam Lithography (LBL) and replication by Nanoimprint Lithography (NIL) processes. The environmental impact of the production method, such as regards material consumption, are considered, and the full cycle from design to final imprint is discussed.