Retention of the original LLC structure in a cross-linked poly(ethylene glycol) diacrylate hydrogel with reinforcement from a silica network

Abstract

Cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogels with uniformly controlled nanoporous structures templated from hexagonal lyotropic liquid crystals (LLC) represent separation membrane materials with potentially high permeability and selectivity due to their high pore density and narrow pore size distribution. However, retaining LLC templated nanostructures is a challenge as the polymer gels are not strong enough to sustain the surface tension during the drying process. In the current study, cross-linked PEGDA gels were reinforced with a silica network synthesized via an in situ sol-gel method, which assists in the retention of the hexagonal LLC structure. The silica precursor does not obstruct the formation of hexagonal phases. After surfactant removal and drying, these hexagonal structures in samples with a certain amount of tetraethoxysilane (TEOS) loading are well retained while the nanostructures are collapsed in samples without silica reinforcement, leading to the hypothesis that the reinforcement provided by the silica network stabilizes the LLC structure. The study examines the conditions necessary for a sufficient and well dispersed silica network in PEGDA gels that contributes to the retention of original LLC structures, which potentially enables broad applications of these gels as biomedical and membrane materials.

Toward the Fabrication of Advanced Nanofiltration Membranes by Controlling Morphologies and Mesochannel Orientations of Hexagonal Lyotropic Liquid Crystals

“…Apart from the efforts from a chemistry perspective, physically reinforcing the nanostructure by introducing a robust silica network to retain the nanostructure was recently proven to be an effective route [ 76 ].…”

“…The introduction of the silica network has been found to reinforce the hexagonal LLCs template and significantly boost the structure retention rate in combination with the CO 2 critical point drying method from our previous work [ 29 , 76 ]. Researchers have been trying to control over the phase curvature chemically or physically to increase the retention rate of nanostructures.…”

In Situ SAXS Measurement and Molecular Dynamics Simulation of Magnetic Alignment of Hexagonal LLC Nanostructures

“…Dodecyltrimethylammonium bromide (DTAB), an anionic surfactant dispersed in water, was used to form the hexagonal LLC structures [30]. A hydrophilic monomer, polyethylene glycol diacrylate (PEGDA), was then added and cross-linked within the aligned cylindrical nanostructure.…”

Improved mechanical properties of antimicrobial poly(N-[3-(dimethylaminopropyl)] methacrylamide) hydrogels prepared by free radical polymerization in the presence of cetyltrimethylammonium bromide as a lyotropic liquid crystal template

“…In some cases, if they present excess water, no oily streaks occur because of lamellar mesophase defects, whereas Maltase crosses are the dominant texture. [33][34][35][36] The aqueous solutions containing CTAB/DMAPMAAm/BIS mixtures and stirred magnetically (at 400 rpm for 12 h) before gelation were prepared under milder conditions compared to mechanical stirring. Although the textures under POM of the TH samples were similar to that in the case of mechanical stirring (hexagonal for TH3/20m, TH2/25m and TH3/25m; hexagonal/lamellar for TH4/25m, TH3/30m and TH4/30m; lamellar for TH2/30m, TH2/40m and TH3/40m; lamellar droplets with maltase crosses for TH4/40m), 2D hexagonal mesophase formation was observed to be more pronounced in the case of magnetic stirring.…”