Preparation And Study Of Thermo-sensitive Graphene And Its Composites

With the development of materials,special nanomaterials have become one of the hot topics in materials science.Specially,graphene not only has the two-dimensional structure with single-layer carbon atom,but also has unique photoelectric and mechanical properties.Thus,the graphene-based materials have been widely used in the fields of adsorption,energy storage,and catalysis.However,the only one type of nanomaterial can not be well applied in the special fields due to the development of composite materials.Therefore,the environmentally responsive and intelligent graphene composites have become the hot topic.In this thesis,the cationic temperature-sensitive polymers were used to prepare the thermo-sensitive graphene composites.In addition,the adsorption performance and heterogeneous catalytic performance of the composites were also studied.The specific studies are as follows:(1)The poly(diallyldimethylammonium chloride)-co-poly(n-isopropylacrylamide)(PDDA-co-PNIPAM)was used as the thermo-sensitive switch and stabilizer to prepare the thermo-sensitive graphene-based hybrid(PDDA-co-PNIPAM/GO)by the electrostatic interactions between the PDDA-co-PNIPAM and GO.The results show that the introduction of PDDA-co-PNIPAM can effectively maintain the morphology of GO.The PDDA-co-PNIPAM/GO can be well dispersed in water and other polar organic solvents.The PDDA-co-PNIPAM polymer is uniformly distributed on the GO,which endows the excellent temperature sensitivity for PDDA-co-PNIPAM/GO.The hybrid material exhibits reversible temperature-dependent phase transition and self-assembly behavior in water.The PDDA-co-PNIPAM/GO is used as a temperature-sensitive adsorbent for the removal of methylene blue from water.PDDA-co-PNIPAM/GO exhibits efficient temperature-controlled adsorption of dyes,which greatly simplifying the separation of dye contaminants from water.(2)The poly(1-vinyl-3-ethylimidazolium bromide)-b-poly(n-isopropylacrylamide)block copolymer(PVEIM-b-PNIPAM)was used as a temperature-controlled switch and stabilizer to prepare the thermo-sensitive graphene-based gold nanocomposite(RGO/PVEIM-bPNIPAM/GNP)by electrostatic interactions,one-pot in-situ growth,and chemical reduction.The results show that the PVEIM-b-PNIPAM stabilizers leads to the uniformly distributed GNPs on the surface of RGO.The new nanocomposite has good dispersibility and temperature sensitivity.Then,the RGO/PVEIM-b-PNIPAM/GNP composite was used as the catalyst for the application in the reduction of 4-nitrophenol.The catalytic activity was examined under different temperature conditions.The results show that the catalytic activity of RGO/PVEIM-b-PNIPAM/GNP decreases sharply with increasing temperature and exhibits excellent temperature response.This thermo-sensitive nanocomposite may be applied as a thermo-switch material for the heterogeneous catalysis,sensors,and smart material devices etc.