| Chemical substances are very important to economic development and social progress,but there are various kinds of real or potential chemical threats challenging to national security.It is of great significance to strengthen the research in the field of chemical security,aiming to further improve China's ability to deal with chemical threats.In chemical security,chemical warfare agents are the greatest hazard to personnel and the biggest threat to national security.Chemical warfare agents,as weapons of mass destruction,are not only an important weight in the game of big powers,but also have gradually developed from large-scale use to more concealed"chemical warfare like"mode such as secondary chemical disasters and chemical terror,which may seriously weaken the combat power and national strength.Strengthening the ability of emergency rescue is the main way to reduce the loss and hazard.Among them,chemical protective clothing is the main equipment for the skin protection of emergency personnel.Skin absorption is an important way of chemical poisoning,and the use of chemical protective clothing with good performance is one of the effective measures to deal with the threat of chemical warfare agents.After more than 70 years of development,China has been equipped with a series of air-permeable and isolated chemical protective clothing.Recently,the United States has successfully developed and mounted a new type of selectively permeable chemical protective clothing.This kind of protective clothing has a comparable protective ability to the isolated protective clothing,and can effectively prevent strong heat stress in hot environments and frostbite in the cold environment.Compared with air-permeable protective clothing,this kind of protective clothing does not use adsorption materials and has good environmental adaptability and strong protection ability.The key component of the selectively permeable protective clothing is the selectively permeable membrane of chemical agents defense and moisture permeable,which is also the focus and development direction of chemical protective materials.It is a revolutionary leap in the field of skin protection,and the research on the selectively permeable membrane is relatively backward in China,which is a"neck sticking"problem restricting the development of this kind of protective clothing in China.Polyelectrolyte membrane(PEM),the polymer membrane with electrolyte groups with good conductivity and ion selectivity,has been widely used in the fuel cell,electrodialysis,diffusion dialysis,and other fields.This kind of membrane material usually has a hydrophilic and hydrophobic microphase separation structure,which can realize the selective permeation of water and organic small molecules,thereby showing great potential in the use of chemical protective clothing.However,very few studies on the PEM protective materials have been reported so far,and most of them focus on the application test of commercial PEM.There is a lack of research on new selectively permeable membrane materials for the application of chemical protective clothing.In this research project,based on the application requirements of chemical protective clothing,the preparation,characterization,protection performance,and protection mechanism of the new selectively permeable membrane were studied and showed in the following:(1)PVDF-g-SSS membrane was prepared by grafting sodium styrene sulfonate(SSS)onto polyvinylidene fluoride(PVDF)by the one-pot method.The effects of sulfonic acid group content on the water uptake,swelling ratio,mechanical properties,and selective permeability of the materials were studied.The results showed that the optimum ion exchange capacity was 1.5-2 mmol g-1,which could provide the tensile strength of 17.4 MPa,water vapor transmission rate(WVTR)of 3072 g m-2 24 h-1,the water/dimethyl phosphonate(DMMP)selectivity of 118 and the water/chloroethyl phenyl sulfide(CEPs)selectivity of 1976.The computer simulation verified the factors influencing the formation of microphase separation structure within membrane materials,and preliminarily explained the selective permeation mechanism of membrane materials to chemical agents and water.According to the relevant military standards and national standards,some of the performance of protective clothing materials were tested.The results showed that the membrane materials have the potential to be used in protective clothing.(2)Low polarity electron-rich aromatic main chain polymer polyphenylene oxide(PPO)was used as matrix resin and sulfonated with chlorosulfonic acid to prepare sulfonated polyphenylene oxide(SPPO).To further improve the barrier property of PVDF membrane material to DMMP,effects of counter ions on water uptake,swelling ratio,mechanical properties,and selective permeability of the materials were studied under different ion-exchange conditions.The results showed that the best ion selection of SPPO membrane is Ca2+,which can achieve28.3%elongation at break,20.8 MPa tensile strength,10%linear swelling ratio,3753 g m-2 24 h-1 water vapor permeation rate,357 water/CEPS selectivity,and 884water/DMMP selectivity.The anti-permeability of the material to DMMP is markedly improved.The factors influencing the formation of microphase separation structure were verified by simulation.The protective performance of the membrane material to mustard gas is one-fourth of that of PVDF-based membrane material.(3)Graphene oxide(GO)was introduced into PEM to further improve the selective permeability of the membrane materials.The surface of GO was grafted with SSS molecular brush to improve the compatibility between GO and PEM and then doped into PVDF-g-SSS membrane solution.The results showed that the compatibility of GO and PVDF-g-SSS is good,and the content of GO-SSS has a great influence on the selective permeability of membrane materials.For PVDF-g-SSS with a sulfonic acid content of 1.67 mmol g-1,the tensile strength of 13.7 MPa,WVTR of 2845 g m-2 24h-1,water/DMMP selectivity of 126,and water/CEPS selectivity of 2297 can be obtained when the content of GO-SSS reaches 0.5%,but the mechanical properties of the membrane are poorer than PVDF-g-SSS,and the elongation at break is 60.6%.(4)To further enhance the protective performance of membrane materials and simultaneously eliminate the risk of secondary pollution,the alkaline polyvinylidene fluoride membrane was designed in this work.Quaternary vinyl benzyl chloride(QVBC),a functional monomer with quaternary ammonium group,was prepared by the reaction of trimethylamine with chloromethyl styrene.Polyvinylidene fluoride grafted polystyrene ammonium chloride(PVDF-g-QVBC)was successfully prepared by alkaline modification and radical polymerization in a simple one-pot process.Through investigating the basic properties,mechanical properties,surface properties,moisture permeability,permeability,and selectivity of the material,it is found that this material has the selective permeability similar to PVDF-g-SSS,and can degrade DMNP,the simulant of Soman.When the optimal content of the quaternary ammonium group was2.14 mmol g-1,it can provide 14.7 MPa tensile strength and 3130 g m-2 24 h-1 WVTR,the selectivity of water/DMMP was 160,the selectivity of water/CEPS was 4060,and the half-life of DMNP degradation was 7.3 min.Verifying the influencing factors of microphase separation structure formation of membrane materials by simulation,combined with protective model,degradation model and physiological model,an integrated model of prevention and degradation is proposed.Theoretical calculation shows that the introduction of degradation performance can reduce the thickness and weight of membrane materials by more than half,and increase the WVTR(25175 g m-2 24h-1)by about 8 times.(5)To enhance the degradation ability of membrane materials on phosphorus-containing compounds at pH<10,and to reduce the stimulation and damage to human skin,this work successfully integrated MOF808(the best candidacy of Zr-MOF series)onto PVDF-g-QVBC by doping process.The results of the degradation test showed that the composite membrane material has good degradation performance in neutral pH solution,which overcomes the defect that MOF808 can only play degradation effect in the N-ethyl morpholine buffer.Compared with the PVDF-g-QVBC membrane,the half-life of 30%MOF808 doped composite membrane(9.4min)to DMNP can be shortened to one-fifth of the PVDF-g-QVBC original membrane(48.68min),The results of soman real chemical warfare agent test showed that the trend of the experiment was consistent with that of the simulation agent.With the increase of MOF808 content,the degradation efficiency of 1 hour increased from48.5%of PVDF-g-QVBC membrane to 85.1%of 30%MOF808 composite membrane. |
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