Thermoresponsive Microgel-Based Free-Standing Membranes: Influence of Different Microgel Cross-Linkers on Membrane Function

Abstract

In this study we show a possibility to produce thermoresponsive, free-standing microgel membranes based on Nisopropylacrylamide (NIPAM) and the UV-sensitive comonomer 2-hydroxy-4-(methacryloyloxy)benzophenone (HMABP). To influence the final network structure and functionality of the membranes, we use different cross-linkers in the microgel syntheses and characterize the resulting structural microgel properties and the swelling behavior by means of AFM, FTIR, and PCS measurements. Varying the cross-linker results in significant changes in the structure and swelling behavior of the individual microgels and has an influence on the incorporation of the comonomer, which is essential for subsequent photochemical membrane formation. We investigate the ion transport through the different membranes by temperature-dependent resistance measurements revealing a sharp increase in resistance when the copolymer microgels reach their collapsed state. The resistance of the membranes can be adjusted by different cross-linkers and the associated incorporation of the comonomer. Furthermore, we show that transferring a reversible cross-linker from a cross-linked state to an un-cross-linked state strongly influences the membrane properties and even reverses the switching behavior, while the mechanical stability of the membrane is maintained.

Photo- and thermo-responsive microgels with supramolecular crosslinks for wavelength tunability of the volume phase transition temperature

“…Microgels have been widely discussed in the literature for a variety of applications, like drug delivery systems, 1 catalysis, 2,3 separation systems 4,5 and, in general, as stimuli-responsive smart materials. 6,7 These functional microgels in aqueous solution can react quickly to stimuli such as temperature, [8][9][10] pH, 11 ionic strength, 12,13 solvent composition and light, 14,15 with in some cases drastic changes in shape, structure and density.…”

Multifunctional Core-Shell Microgels as Pd-Nanoparticle Containing Nanoreactors With Enhanced Catalytic Turnover

“…In a recent study, we were able to use this comonomer to prepare freestanding microgel films. The prepared films can be transferred onto various substrates or can be used as free-standing diffusion barriers (Dirksen et al, 2022). The incorporation of HMABP was characterized by means of PCS and Fourier transform infrared spectroscopy (FTIR).…”

Synthesis and study of enhanced electrochemical properties of NiO nanoparticles deposited on TiO2 nanotubes

“…Nonetheless, anti-electrolytes based fuel cells modules have many extensions since energy units dependent on acidic electrolytes work principally with Pt-based catalysts and this reliance makes them more costly. [22][23][24][25][26][27][28] Anyway, the AFCs can work with moderately more affordable metals, for example, Au, Ag, and Ni. There are many benefits related to the AFCs, which make them more practical to make than acidic electrolytes-based energy fuel cells.…”

“…There are many benefits related to the AFCs, which make them more practical to make than acidic electrolytes-based energy fuel cells. [22][23][24][25] Figure 1 shows the schematic of an alkaline fuel cell where the charge transporters are hydroxyl particles that relocate from cathode to anode where the reaction with hydrogen produces water and electrons.…”

“…There are many benefits related to the AFCs, which make them more practical to make than acidic electrolytes‐based energy fuel cells. [ 22–25 ]…”