Functionalized Modification Of Graphene Oxide And Its Application In Antioxidant And Oil-water Separation

Since the first report for graphene in 2004,due to its excellent physical properties in terms of electrical,thermal,optical and magnetic fields,it is possible to disrupt many traditional industries.However,the surface of graphene almost does not contain any groups,resulting in processing difficulties and seriously limiting its wide range of practical applications.As the most important derivative of graphene,graphene oxide?GO?is also a two-dimensional layered material with a single atomic layer,GO is usually used as a precursor for the preparation of graphene because of low preparation cost,simple process,large scale production and good solubility.At present,a variety of functionalized graphene oxide has been used in drug delivery,energy storage materials,catalysis and other fields.However,the development of GO properties and applications is not blameless,especially the application of functional GO.The modified Hummers method was used to prepare graphene oxide,the preparation of functionalized GO and its application in anti-thermal oxygen aging and oil-water separation are further explored in this paper.The main contents and results of the thesis include the following aspects:Firstly,functionalized graphene oxide containing hindered phenol and urethane groups?HPUGO?was prepared by grafting 2,6-Di-tert-butyl-4-hydroxymethyl phenol?DBHMP?onto graphene oxide?GO?using isophorone diisocyanate as bridging agent and dibutyltin dilaurate?DBTDL?as catalyst,and its chemical structure,micro-morphology,and wettability were characterized.Compared with GO,the results showed that the interlayer distance of HPUGO increased from 0.79nm to 1.40nm.the water contact angle of HPUGO increased from 28^o to 91^o,and the effective grafting rate of DBHMP was 18.34%.NR/HPUGO nanocomposites were prepared by latex blending,flocculation drying and open-smelting vulcanization.And SEM,XRD and TEM showed that HPTGO achieved excellent dispersion in NR matrix.Compared with the neat NR vulcanizates,the initial degradation temperature(T_onset)of NR vulcanizates with 2 phr HPUGO?NR/HPUGO-2?in the air was increased from338.8^oC to 364.8^oC,the temperature of maximum weight loss rate(T_max)was increased from372.9^oC to 394.5^oC,The oxidation induction time of NR/HPUGO-2 increased from 26min to78min,the retention of elongation at break and tensile strength of NR/HPUGO-2 reached to0.51 and 0.57 from 0.25 and 0.37 after thermo-oxidative aging for 96 h.The excellent antioxidant properties of HPUGO is attribute to the combination of HPUGO's lamellar structure serving as a gas barrier and the synergistic effect of hindered phenolic groups and urethane groups to capture free radicals.Secondly,the hydrolysis of-Si?OCH₃?₃ on the silane coupling agent?KH590?undergoes condensation reaction with the hydroxyl groups on GO to obtain mercapto-containing graphene oxide?mGO?.After that,mGO and hindered phenol compounds?2-tert-butyl-6-?3-tert-butyl-2-hydroxy-5-methylphenyl?methyl-4-methylp-henyl acrylate,GM?with unsaturated double bond occurred thiol-ene addition reaction,and the functionalized graphene oxide containing hindered phenolic groups and thioether bonds?HPTGO?was prepared successfully.The chemical structure,morphology and wettability of HPTGO were characterized by FT-IR,XRD,XPS,SEM,WCA and TGA.Compared with GO,the results show that the interlayer spacing of HPTGO increases,the water contact angle of HPTGO reaches 134^o,and the effective grafting rate of small molecule antioxidant?GM?is as high as 31.08%.NR/HPTGO nanocomposites were prepared by latex blending,flocculation drying and open-smelting vulcanization.The pictures of SEM and TEM showed that HPTGO achieved excellent dispersion in NR matrix.The initial degradation temperature of NR vulcanizates with 2 phr HPTGO?NR/HPTGO-2?in the air reached to 372.8^oC,the temperature of maximum weight loss rate was increased to 391.8^oC,The oxidation induction time of NR/HPTGO-2 increased from 26min to 78min,the retention of elongation at break and tensile strength of NR/HPTGO-2 reached to 0.56 and 0.62 after thermo-oxidative aging for 96 h.The excellent antioxidant properties of HPTGO is attribute to the combination of HPTGO's lamellar structure serving as a gas barrier and the synergistic effect of hindered phenolic groups and thioether bonds to capture free radicals.Finally,thiolated graphene?GSH?was prepared by one-pot method using thiourea as reductant,and the chemical structure and microstructure of GSH was confirmed by FT-IR,XRD,XPS and SEM.After the thiolated graphene with the water contact angle?WCA?of128^o was dispersed in ethanol,the superhydrophobic polyurethane sponge for oil-water separation was fabricated via a simple dipping-drying process,the hydrophobicity of GSH and the roughness after adsorption are important factors for the success of superhydrophobic sponge.The WCAs of the as-prepared sponges were largely determined by the loading of GSH,and the WCAs were 93^o,136.2^o,157.0^o and 160.5^o with GSH loadings at,0.0%,2.5%,5.0%and 7.5%,respectively.The GSH-based superhydrophobic sponge exhibited high absorption selectivity for different organic solvents and oils,the absorption capacity of can reach 29.5-90.4 times the weight of sponge.and there was no decrease afte10 absorption cycles.Importantly,with the oil-water separation device composed of pump,rubber tubes and GSH-based sponge,the separation efficiency of toluene from water reached 99.7%,and still maintained 99.5%after 5 cycles.Additionally,GSH-based sponge also effectively shortened burning time and reduced black smoke in the combustion process,demonstrating good flame retardancy.Our findings provided a new strategy to fabricate superhydrophobic materials for oil-water separation,showing the great potential in large-scale practical application.