Robust Bioinspired Graphene Film via π–π Cross-linking

Abstract

Graphene composite films inspired by nacre are the subject of ongoing research efforts to optimize their properties for applications in flexible energy devices. Noncovalent interactions do not cause interruption of the delocalized conjugated π-electron system, thus preserving graphene's excellent properties. Herein, we synthesized a conjugated molecule with pyrene groups on both ends of a long linear chain (AP-DSS) from 1-aminopyrene (AP) and disuccinimidyl suberate (DSS). The AP-DSS molecules are used to cross-link adjacent graphene nanosheets via π-π interfacial interactions to improve properties of graphene films. The tensile strength and toughness of resultant graphene films were 4.1 and 6.4 times higher, respectively, than that of pure rGO film. More remarkably, the electrical conductivity showed a simultaneous improvement, which is rare to be achieved in other kinds of covalent or noncovalent functionalization. Such integration demonstrates the advantage of this work to previously reported noncovalent functionalization of graphene.

Role of Interface Interactions in the Construction of GO‐Based Artificial Nacres

“…[51,58,90] Figure 2 shows that in the past decade, an increasing research effort has been made to improve the mechanical properties of graphene-based nanocomposites by various interfacial www.advmatinterfaces.de modifications. [48,75,[91][92][93][94] The interfacial crosslinking strategies contain hydrogen bonding, [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114] ionic bonding, [81,[115][116][117][118] π-π interaction, [119][120][121] and covalent bonding. Inspired by nacre, a vast variety of highperformance GO-based nanocomposites and their reduced counterparts, including 1D fibers, 2D films, and 3D bulk materials, have been successfully constructed by interfacial crosslinking and building block toughening.…”

“…Recently, Ni et al [119] synthesized a kind of long linear conjugated molecule with pyrene groups on both ends from 1-aminopyrene (AP) and disuccinimidyl suberate (DSS). Recently, Ni et al [119] synthesized a kind of long linear conjugated molecule with pyrene groups on both ends from 1-aminopyrene (AP) and disuccinimidyl suberate (DSS).…”

“…[2] Thus, the different interface interactions could also be properly incorporated into one GAN to induce synergistic effect, thereby leading to significant enhancement in mechanical properties. Moreover, when selecting suitable interface interactions, such as π-π interaction, [119] covalent bonding via PCDO, [126] etc., the synergistically bridged GANs could also demonstrate excellent electrical conductivity. Moreover, when selecting suitable interface interactions, such as π-π interaction, [119] covalent bonding via PCDO, [126] etc., the synergistically bridged GANs could also demonstrate excellent electrical conductivity.…”

“…The moderate density of bridging via long-chain molecules, polymers, and complex biomacromolecules could usually cause considerable enhancement in toughness, such as rGO-PCDO, [126] rGO-PDA, [122] and rGO-SF nanocomposites. The small metal ions, such as Ni 2+ , [133] Cu 2+ , [138] and Ca 2+ , [81] etc., which could induce ionic bonding with GO [81] π-π interaction rGO-AP-DSS 4.11 6.44 1.32 [119] graphene-py 2 -PEG-py 2 2.93 -0.01 [120] graphene-py-PEG-py 2.57 -0.03 [120] graphene-ph-PEG-ph 1.96 -0.05 [120] rGO-PAAP Hydrogen bonding and π-π interaction rGO-PAPB 2.30 4.52 0.96 [131] GO-SSEBS 1. Generally, the insulated polymeric crosslinkers, such as PVA, [102] PAA, [110] and HPC, [138] etc., significantly decrease the electrical conductivity of GANs.…”

“…The small metal ions, such as Ni 2+ , [133] Cu 2+ , [138] and Ca 2+ , [81] etc., which could induce ionic bonding with GO [81] π-π interaction rGO-AP-DSS 4.11 6.44 1.32 [119] graphene-py 2 -PEG-py 2 2.93 -0.01 [120] graphene-py-PEG-py 2.57 -0.03 [120] graphene-ph-PEG-ph 1.96 -0.05 [120] rGO-PAAP Hydrogen bonding and π-π interaction rGO-PAPB 2.30 4.52 0.96 [131] GO-SSEBS 1. Some linear molecular crosslinkers, such as π-π bonder of AP-DSS [119] and covalent bonder of PCDO with conjugated backbones, [126] could enhance the alignment of graphene nanosheets, thereby resulting in the enhancement in electrical conductivity. Note that even though the π-π interaction usually has less effect on the conjugated structure of graphene nanosheets, the polymeric π-π bonder, such as py 2 -PEG-py 2 , py-PEG-py, and ph-PEG-ph, [120] is detrimental to the electron transfer between adjacent graphene nanosheets, thereby decreasing the electrical conductivity.…”