Porous Membranes Built Up from Hydrophilic Poly(ionic liquid)s

Review of ionic liquid and ionogel-based biomaterials for advanced drug delivery

Ionic liquids (ILs) play a crucial role in the design of novel materials. The ionic nature of ILs provides numerous advantages in drug delivery, acting as a green solvent or active ingredient to enhance the solubility, permeability, and binding efficiency of drugs. They could also function as a structuring agent in the development of nano/micro particles for drug delivery, including micelles, vesicles, gels, emulsion, and more. This review summarize the ILs and IL-based gel structures with their advanced drug delivery applications. The first part of review focuses on the role of ILs in drug formulation and the applications of ILs in drug delivery. The second part of review offers a comprehensive overview of recent drug delivery applications of IL-based gel. It aims to offer new perspectives and attract more attention to open up new avenues in the biomedical applications of ILs and IL-based gels.

Ferrocene-Containing Porous Poly(Ionic Liquid) Membranes: Synthesis and Application as Sacrificial Template for Porous Iron Oxide Films

Herein, the fabrication of iron-containing porous polyelectrolyte membranes (PPMs) via ionic complexation between an imidazolium-based poly(ionic liquid) (PIL) and 1,1-ferrocenedicarboxylic acid is reported. The key parameters to control the microstructure of porous hybrid membranes are investigated in detail. Further aerobic pyrolysis of such porous hybrid membranes at 900 °C can transfer the ferrocene-containing PPMs into freestanding porous iron oxide films. This process points out a sacrificial template function of porous poly(ionic liquid) membranes in the fabrication of porous metal oxide films.

Functions of Ionic Liquids in Preparing Membranes for Liquid Separations: A Review

Membranes are widely used for liquid separations such as removing solute components from solvents or liquid/liquid separations. Due to negligible vapor pressure, adjustable physical properties, and thermal stability, the application of ionic liquids (ILs) has been extended to fabricating a myriad of membranes for liquid separations. A comprehensive overview of the recent developments in ILs in fabricating membranes for liquid separations is highlighted in this review article. Four major functions of ILs are discussed in detail, including their usage as (i) raw membrane materials, (ii) physical additives, (iii) chemical modifiers, and (iv) solvents. Meanwhile, the applications of IL assisted membranes are discussed, highlighting the issues, challenges, and future perspectives of these IL assisted membranes in liquid separations.

Synthesis of poly(ionic liquid) for trifunctional epoxy resin with simultaneously enhancing the toughness, thermal and dielectric performances

Poly(ionic liquid) (PIL), integrating the characteristics of both polymers and ionic liquid, is synthesized and employed to modify diglycidyl-4,5-epoxy-cyclohexane-1,2-dicarboxylate (TDE-85). With the addition of PIL, the fracture toughness, and thermal and dielectric performances of TDE-85 were discovered to be simultaneously improved, meanwhile the tensile modulus and strength is increased. Upon an optimal loading of 3 wt% PIL, the critical stress intensity factor (K _IC), tensile modulus and strength are raised by 92.9%, 13.3% and 10.7%, respectively. Multi-toughening mechanisms due to spherical domains of PIL formed in TDE-85 during curing are responsible for the improved toughness. Moreover, the dielectric and thermal properties of TDE-85 are also enhanced by adding PIL. With the optimal addition of 5 wt% PIL, the dielectric constant of the composites is enhanced by 62.5%, the glass transition temperature is increased by 16.58 °C and the residual weight of carbon is increased by 59%.

Controlled ATRP Synthesis of Novel Linear-Dendritic Block Copolymers and Their Directed Self-Assembly in Breath Figure Arrays

Herein, we report the formation and characterization of novel amphiphilic linear-dendritic block copolymers (LDBCs) composed of hydrophilic dendritic poly(ether-ester), PEE, blocks and hydrophobic linear poly(styrene), PSt. The LDBCs are synthesized via controlled atom transfer radical polymerization (ATRP) initiated by a PEE macroinitiator. The copolymers formed have narrow molecular mass distributions and are designated as LGn-PSt Mn, in which LG represents the PEE fragment, n denotes the generation of the dendron (n = 1⁻3), and Mn refers to the average molecular mass of the LDBC (Mn = 3.5⁻68 kDa). The obtained LDBCs are utilized to fabricate honeycomb films by a static "breath figure" (BF) technique. The copolymer composition strongly affects the film morphology. LDBCs bearing acetonide dendron end groups produce honeycomb films when the PEE fraction is lower than 20%. Pore uniformity increases as the PEE content decreases. For LDBCs with hydroxyl end groups, only the first generation LDBCs yield BF films, but with a significantly smaller pore size (0.23 μm vs. 1⁻2 μm, respectively). Although higher generation LDBCs with free hydroxyl end groups fail to generate honeycomb films by themselves, the use of a cosolvent or addition of homo PSt leads to BF films with a controllable pore size (3.7⁻0.42 μm), depending on the LDBC content. Palladium complexes within the two triazole groups in each of the dendron's branching moieties can also fine-tune the morphology of the BF films.

Organic Molecule-Driven Polymeric Actuators

Inspired by the motions of plant tissues in response to external stimuli, significant attention has been devoted to the development of actuating polymeric materials. In particular, polymeric actuators driven by organic molecules have been designed due to their combined superiorities of tunable functional monomers, designable chemical structures, and variable structural anisotropy. Here, the recent progress is summarized in terms of material synthesis, structure design, polymer-solvent interaction, and actuating performance. In addition, various possibilities for practical applications, including the ability to sense chemical vapors and solvent isomers, and future directions to satisfy the requirement of sensing and smart systems are also highlighted.

Charge transport and glassy dynamics in polymeric ionic liquids as reflected by their inter- and intramolecular interactions

Polymeric ionic liquids (PILs) form a novel class of materials in which the extraordinary properties of ionic liquids (ILs) are combined with the mechanical stability of polymeric systems qualifying them for multifold applications. In the present study broadband dielectric spectroscopy (BDS), Fourier transform infrared spectroscopy (FTIR), AC-chip calorimetry (ACC) and differential scanning calorimetry (DSC) are combined in order to unravel the interplay between charge transport and glassy dynamics. Three low molecular weight ILs and their polymeric correspondents are studied with systematic variations of anions and cations. For all examined samples charge transport takes place by glassy dynamics assisted hopping conduction. In contrast to low molecular weight ILs the thermal activation of DC conductivity for the polymeric systems changes from a Vogel-Fulcher-Tammann- to an Arrhenius-dependence at a (sample specific) temperature Tσ0. This temperature has been widely discussed to coincide with the glass transition temperature Tg, a refined analysis, instead, reveals Tσ0 of all PILs under study at up to 80 K higher values. In effect, below the Tσ0 charge transport in PILs becomes more efficient - albeit on a much lower level compared to the low molecular weight pendants - indicating conduction paths along the polymer chain. This is corroborated by analysing the temperature dependence of specific IR-active vibrations showing at Tσ0 distinct changes in the spectral position and the oscillator strength, whereas other molecular units are not affected. This leads to the identification of charge transport responsive (CTR) as well as charge transport irresponsive (CTI) moieties and paves the way to a refined molecular understanding of electrical conduction in PILs.

Porous Polyelectrolytes: The Interplay of Charge and Pores for New Functionalities

The past decade has witnessed rapid advances in porous polyelectrolytes and there is tremendous interest in their synthesis as well as their applications in environmental, energy, biomedicine, and catalysis technologies. Research on porous polyelectrolytes is motivated by the flexible choice of functional organic groups and processing technologies as well as the synergy of the charge and pores spanning length scales from individual polyelectrolyte backbones to their nano-/micro-superstructures. This Review surveys recent progress in porous polyelectrolytes including membranes, particles, scaffolds, and high surface area powders/resins as well as their derivatives. The focus is the interplay between surface chemistry, Columbic interaction, and pore confinement that defines new chemistry and physics in such materials for applications in energy conversion, molecular separation, water purification, sensing/actuation, catalysis, tissue engineering, and nanomedicine.

Frontiers in poly(ionic liquid)s: syntheses and applications

We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed. Furthermore, the near-term applications of PILs in multiple fields, such as their use in electrochemical energy materials, stimuli-responsive materials, carbon materials, and antimicrobial materials, in catalysis, in sensors, in absorption and in separation materials, as well as several special-interest applications, are described in detail. We also discuss the limitations of PIL applications, efforts to improve PIL physics, and likely future developments.

Anion-Responsive Poly(ionic liquid)s Gating Membranes with Tunable Hydrodynamic Permeability

Novel anion-responsive "intelligent" membranes with functional gates are fabricated by filling polyethersulfone microporous membranes with poly(ionic liquid)s (PILs) gels. The wetting properties of the PILs could be controlled by changing their counteranions (CAs), and thus, the filled PILs gel gates in the membrane pores could spontaneously switch from the "closed" state to the "open" one by recognizing the hydrophilic CAs in the environment and vice versa. As a result, the fluxes of the "intelligent" membranes could be tuned from a very low level (0 mL/m²·mmHg for Cl^-, Br^-, and BF₄^-) to a relatively high one (430 mL/m²·mmHg for TFSI). The anion-responsive gating behavior of the PILs filled membranes is fast, reversible, and reproducible. In addition, the "intelligent" membranes are sensitive to contact time and ion concentrations of the hydrophobic CA species. The proposed anion-responsive "intelligent" membranes are highly attractive for ion-recognizable chemical/biomedical separations and purifications.

Covalent Cross-Linking of Porous Poly(ionic liquid) Membrane via a Triazine Network

Porous poly(ionic liquid) membranes that were prepared via electrostatic cross-linking were subsequently covalently cross-linked via formation of a 1,3,5-triazine network. The additional covalent cross-links do not affect pore size and pore size distribution of the membranes and stabilize them toward salt solutions of high ionic strength, enabling the membranes to work in a broader environmental window.

Anion exchange: a novel way of preparing hierarchical porous structure in poly(ionic liquid)s

The exchange of bulky salicylate and its dimers/clusters in PILs by other smaller anions increased specific surface area and fabricated a hierarchical porous structure.