Khawas Koomkoom, Daripa Soumili, Kumari Pallavi, Kuila Biplab Kumar
Center for Applied Chemistry, Central University of Jharkhand, Brambe, Ranchi 835205, Jharkhand, India.
Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, Uttar Pradesh, India.
ACS Omega. 2018 Jun 29;3(6):7106-7116. doi: 10.1021/acsomega.8b00883. eCollection 2018 Jun 30.
Here, we have discussed the preparation of a highly solution processable graphene from a novel supramolecular assembly consisting of block copolymer polystyrene--poly(4-vinylpyridine) (PS--P4VP) and pyrenebutyric acid (PBA)-modified reduced graphene oxide (RGO). The PBA molecules anchored on the graphene surface form supramolecules with PS--P4VP through H-bonding between the carboxylic acid group of 1-pyrenebutyric acid and the pyridine ring of P4VP. The formation of a supramolecular assembly results in a highly stable solution of reduced graphene oxide in common organic solvents, such as 1,4-dioxane and chloroform. Highly transparent and mechanically stable thin films can be deposited from these supramolecular assemblies on a relatively smooth surface of different substrates such as silicon wafer, glass, indium tin oxide, and flexible polymer substrates like poly(ethylene terephthalate). The graphene surface modifier (PBA) can be selectively removed from the thin film of the hybrid material by simple dissolution, resulting in a porous structure. Hybrid thin films of around 50 nm thickness exhibit interesting electrochemical properties with an areal capacitance value of 17.73 μF/cm at a current density of 2.66 μA/cm and good electrochemical stability. The pendent P4VP chains present in the composite thin film were further exploited for electrochemical detection of metal ions. The electrical measurement of the thin film sandwich structure of the composite shows a bipolar resistive switching memory with hysteresis-like current-voltage characteristics and electrical bistability. The OFF state shows ohmic conduction at a lower voltage and trap-free space-charge-limited current (SCLC) conduction at high voltage, whereas the ON state conduction is controlled by ohmic at low bias voltage, trap-free SCLC at moderate voltage, and tarp-assisted SCLC at high voltage.
在此，我们讨论了一种由嵌段共聚物聚苯乙烯-聚（4-乙烯基吡啶）（PS-P4VP）和芘丁酸（PBA）修饰的还原氧化石墨烯（RGO）组成的新型超分子组装体制备高度可溶液加工石墨烯的方法。锚定在石墨烯表面的PBA分子通过1-芘丁酸的羧基与P4VP的吡啶环之间的氢键与PS-P4VP形成超分子。超分子组装体的形成导致还原氧化石墨烯在常见有机溶剂（如1,4-二氧六环和氯仿）中形成高度稳定的溶液。可以从这些超分子组装体在不同衬底（如硅片、玻璃、氧化铟锡）以及柔性聚合物衬底（如聚对苯二甲酸乙二酯）等相对光滑的表面上沉积出高度透明且机械稳定的薄膜。通过简单溶解可以从杂化材料薄膜中选择性地去除石墨烯表面改性剂（PBA），从而形成多孔结构。厚度约为50 nm的杂化薄膜表现出有趣的电化学性质，在电流密度为2.66 μA/cm²时面积电容值为17.73 μF/cm²，并且具有良好的电化学稳定性。复合薄膜中存在的悬垂P4VP链进一步用于金属离子的电化学检测。复合材料薄膜三明治结构的电学测量显示出具有类似滞后电流-电压特性和电双稳性的双极电阻开关存储器。关态在较低电压下表现出欧姆传导，在高电压下表现出无陷阱空间电荷限制电流（SCLC）传导，而开态传导在低偏压下由欧姆控制，在中等电压下由无陷阱SCLC控制，在高电压下由陷阱辅助SCLC控制。
