| Though the traditional barrier materials for chemical agent shielding can block the vast majority of toxic chemical agents, they are not comfortable for soldiers to wear for a long time due to low water vapor permeability and heat stress issues. The ideal protective garment materials should have the ability to selectively block toxic substances, meanwhile possess high water vapor permeability. This thesis attempts to take advantage of the ordered structure of crosslinkable lyotropic liquid crystals (LLCs) to improve the water vapor permeability of the traditional chemical protective materials. The research contents can be divided into the following three parts:Firstly, the thesis studies on a lyotropic liquid crystal/butyl rubber (LLC/BR) breathable chemical-barrier material. A novel crosslinked acrylate-type LLC monomer based on a gemini ammonium surfactant is conveniently prepared in two steps. Polarized optical microscopy and samll-angle X-ray scattering are used to elucidate the LLC phases. This new LLC monomer predominantly forms lamellar lyotropic mesophase, and meanwhile when mixed with 17 wt%-22 wt% water at 55℃-79℃, it presents an unidentified X phase which is quite similar to bicontinuous cubic phase. By hot-pressing and photo-crosslinking on a porous polyethersulfone (PES)-supported membrane, a series of composite membranes of LLC/BR-PES are made. The crosslinked LLC membranes can retain the original mesophase and build hydrophilic nanochannels. The average water vapour flux of an X-phase LLC/BR-PES composite membrane is 630 ± 50 g·m-2 day-1, which is higher than the performances of L-phase LLC/BR-PES composite membranes (310 ± 20 g·m-2·day-1-510± 40 g·m-2·day-1). In addition, the water permeability properties of these novel membranes are better than the previously reported corsslinked LLC membranes (200 g·m-2·day-1 -440 g·m-2·day-1).Secondly, the thesis talks about a post-functionalization study of polybutadiene rubber. The diol groups are introduced by a thiol-ene reaction between 1-thioglycerol and the double bonds of poly-butadiene backbones. Furthermore, a series of composite films are prepared by coating modified polybutadiene rubber on a porous PES supporting film. Before adding the crosslinking agent into the mixture containing polybutadiene rubber,1-thioglycerol and photo-initiator, UV irradiation for a short period of time can prepolymerize the mixture, which is good for coating due to the increased viscosity. The performances of films are investigated by using Fourier-transform infrared spectrometer analysis, thermogravimetric analysis and the equilibrium swelling techniques. With the increase of the added amount of 1-thioglycerol, the intensity of C=C peak of the film significantly decreases in FT-IR spectrum. After the introduction of diol groups, the crosslinking density of the film increase, however, the thermal stability declines, the initial thermal-decomposition temperature of the functionalized films declines as well. The experiment of testing the membranes’water vapor permeability shows that the newly introduced diol units can double the water vapor transmission rate of the original polybutadiene rubber film.Finally, the thesis works on a breathable barrier material based on nanoporous poly(ionic liquid) membranes. The hydrophobic poly[1-cyanomethyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)-imide] (PCMVImTfzN) is prepared in three steps. After PCMVImTf2N is mixed with poly(acrylic acid) (PAA), the nanoporous poly(ionic liquid) membranes can be obtained by simple solution casting and soaking steps. During the solution casting, the choice of solvents has little effect on the water vapor permeability of the films. The average water vapor permeability of the films which use N, N-dimethylformamide (DMF) as the solvent is 629 g·m-2·day-1, which is lower than the one using N, N-dimethylacetamide (DMAc)(646g·m-2·day-1). |
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