【作者】 张林；

【导师】 李红强； 杨育农；

【作者基本信息】 华南理工大学 ， 材料工程（专业学位）， 2018， 硕士

【摘要】 自2004年石墨烯问世以来,由于其在电学、热学、光学和磁学等方面优异的物理特性,引发了科研工作者的研究热潮。但石墨烯表面几乎不含任何基团,加工困难,严重限制了自身的广泛应用。作为石墨烯最重要的一种衍生物,氧化石墨烯具有制备成本低、工艺简单、可规模化生产、良好的加工性等优点。近年来,利用GO表面上的活性基团,通过还原、元素掺杂、共价或非共价修饰等手段使其功能化,已成功应用于药物输送、储能材料、催化、复合材料等领域。本课题采用改良的Hummers法制备氧化石墨烯,通过对其接枝抗氧化基团和巯基化并分别应用于抗氧化和油水分离领域,不仅丰富了氧化石墨烯的功能化方法,而且进一步拓展了其应用领域。论文的主要研究内容和结果包括以下几个方面:（1）以二月桂酸二丁基锡（DBTDL）为催化剂,以异佛尔酮二异氰酸酯（IPDI）为桥接剂,利用伯、仲异氢酸酯基的反应活性差异,通过控制反应温度,使IPDI上的仲-NCO和伯-NCO分别与2,6-二叔丁基-4-羟基甲基苯酚（DBHMP）的伯羟基和GO上的羟基反应,制得含受阻酚和氨基甲酸酯基团的功能化氧化石墨烯（HPUGO）,并对其化学结构、微观形貌及亲疏水性进行了表征。结果表明,与GO相比,HPUGO的层间距由0.79nm增加至1.40nm,水接触角由28^o增加至91^o,小分子抗氧剂DBHMP相对接枝率达到18.34%。在与天然橡胶（NR）胶乳共混、絮凝干燥、开炼和硫化后,制备了NR/HPUGO纳米复合硫化胶。SEM、XRD和TEM结果表明HPUGO在NR基体中分散均匀。与未加HPUGO的NR硫化胶相比,添2phrHPUGO的复合硫化胶在空气氛围中的初始失重温度(T_onset)由338.8 ^oC提高至372.8 ^oC,最大失重速率温度(T_max)由372.9 ^oC提高至394.5^oC,老化96 h后的断裂伸长率保持率和拉伸强度保持率分别由0.25和0.37增加至0.51和0.57。这主要是由于HPUGO能有效阻隔氧气的渗透以及受阻酚基团和氨基甲酸酯基团之间的协效作用。（2）首先采用γ-巯丙基三甲氧基硅烷（KH590）对氧化石墨烯改性,得到含巯基的氧化石墨烯（mGO）,然后在三乙胺的催化作用下与含不饱和C=C双键的受阻酚化合物2-叔丁基-6-（3-叔丁基-5-甲基-2-羟苯基）-4-甲基苯基丙烯酸酯（GM）发生巯烯加成反应,制得含受阻酚和硫醚键的功能化氧化石墨烯（HPTGO）。利用FT-IR、XRD、XPS、SEM、WCA、TGA等测试手段对HPTGO的化学结构、微观形貌及亲疏水性进行表征。结果分析表明,与GO相比,HPTGO的层间距增大,水接触角达到134^o,小分子抗氧剂GM的相对接枝率达31.08%。将HPTGO与NR胶乳共混、絮凝干燥、开炼和硫化后,制备了NR/HPTGO纳米复合硫化胶。SEM和TEM结果表明HPTGO较好地分散在NR基体中。添加了2phr HPTGO的NR纳米复合硫化胶在空气氛围下的T_onset和T_max分别达到372.8^oC和391.8C,老化96 h后的断裂伸长率保持率和拉伸强度保持率分别增加至0.57和0.63。与HPUGO相比,HPTGO具有更好的抗热氧老化性能,这除了石墨烯片层能有效阻隔氧气的渗透之外,GM在HPTGO上的接枝率更高,同时受阻酚基团和硫醚键之间也具有协同抗氧作用。（3）以硫脲为还原剂,采用一锅法制备出水接触角为128^o的疏水性巯基化石墨烯（GSH）,并利用FT-IR、XRD、XPS、SEM等确认了其化学结构及微观形貌。将GSH分散于乙醇后,以普通的聚氨酯海绵为载体,通过浸涂-干燥的方法制备出基于GSH的疏水性海绵。当GSH的固载量为0.0%、2.5%、5.0%和7.5%时,海绵接触角分别达到93^o、136.2^o、157^o和160.5^o。选用5%固载量的超疏水海绵进行油水分离研究,其不仅油水选择性高,油吸收能力强,可以达到自身重量的29.5-90.4倍,且十次循环吸收后的油吸收能力基本无降低。将其与水泵和胶管搭建成油水分离装置,油水分离效率可达99.7%。在经过五次循环后,分离效率仍保持在99.5%,表现出良好的可循环使用性。将聚氨酯海绵和超疏水海绵进行燃烧实验,发现超疏水海绵的燃烧时间短、产生的黑烟和刺激性气体少,且燃烧后的海绵能够保持原有的骨架形状,具有较好的阻燃性。更多还原

【Abstract】 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.更多还原