| Graphene is an atom-thick two-dimensional crystal with excellent properties.Graphene macroscopic assemblies with different dimensions extended their application fields,especially its two-dimensional macroscaopic assemblies.In this dissertation,we focus on the preparation of ultrastrong,ultratough,highly conductive,and multifunctional chemically modifiedgraphene-based films,and aim to simplify the fabrication procedure,reveal the mechanism of mechanical enhancement,as well as improve their integrated performance.We rationally designed and synthesized a polymer gel promoters poly?acrylic acid-co-?4-acrylamidophenyl?borocic acid??PAPB0.2?of graphene oxide?GO?hydrogel,and developed a facile gel-film transformation?GFT?method to fabricatean ultrastrong,ultratough,and highly conductive reduced graphene oxide?rGO?/PAPB0.2composite film.The tensile strength,strain at break??b?and toughness of the rGO films with only 4 wt% PAPB0.2 were measured to be 382 ± 12 MPa,4.31 ± 0.08%,and 7.50 ± 0.40 MJ m-3,respectively.More importantly,this film has a high conductivity(337 ± 12 S cm-1)which is comparable to that of intrinsic rGO film(350 ± 13 S cm-1).The simple GFT technique is cost-effective,eco-friendly,and scalable to industry levels to fabricate chemically modified graphene films with arbitrary sizes,shapes,and thicknesses.All chemically modified graphene films and fibers with excellent mechanical properties were fabricated via a facile acid-induced microstructure control method without introducing any foreign cross-linking polymers.The as-prepared films exhibitsuperior tensile strength up to 447±29MPa and toughness as high as 6.39 ± 0.06 MJ m-3,which remarkably surpass most of graphene-based films.More importantly,these additive-free films present outstanding thermal stability which largely outperform that of nacre-mimetic binary graphene/polymer composites films.In addition,the conductive,flexible,and fire-resistant fibers can work well as a conductive wire under harsh condition.Our methodology proposed here provides a new insight for deep understanding the relationship between microstructure and mechanical properties,meanwhile paving the way for massive requirments of the robust,conductive,and thermally stable graphene-based macroscopic architectures.Robust pristine GO films and rGO films with arbitrary sizeswere prepared by controlling the chemical structures of GO sheets combined with thermal annealing at 70 oC.The GO films are mechanically stable in water,ultrastrong with tensile strength of 453 ± 17 MPa.The corresponding rGO films obtained by chemical reduction have a tensile strength up to 614 ± 12 MPa,as strong as AISI 304 stainless steel?585 MPa?.They also have a high toughness of 14.89 ± 1.02 MJ m-3,together with a high conductivity of 802 ± 29 S cm-1 and a thermal conductivity as high as 524 ± 36 W m-1 K-1.Solution processed,highly conductive chemically modified graphene film is prepared by using large-size,high-quality,monolayer graphene oxide and few layer graphite oxide as building block via facile solution evaporation method.The conductivity of the film doped by iodine is as high as 1440 S cm-1 and the strength of films is up to 387 ± 55 MPa.This highly conductive rGO film was used as lightweight,foldable current collector in supercapacitor and deliver a outstanding rate-capability. |
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