| Graphene, known as a’dream material’, has increasingly shown its unique charm in the fields of chemistry, physics and materials science. However, some limitations exist within the present fabrication of graphene. It is still challenging to obtain homogeneous, stable or functional consistent graphene and its hybrid. To resolve the above problems, one-step intercalation polymerization of monomer cation was put forwards to obtain graphene/polymer hybrids. The proposed intercalation method will open a new path for the design and fabrication of graphene hybrids. Meanwhile, the related theoretical study involved with the intercalation and their electromagnetic regulations also lay scientific basis for in-depth understanding of two-dimensional confined polymerization mechanisms. This thesis focused on the experimental study on the intercalation inside expanded graphite, natural graphite and graphite oxide, as well as the process analysis of the intercalation polymerization based on DFT calculation and their relative enhanced electromagnetic properties.1. Graphene/polyaniline hybrids could be efficiently synthesized through the in-situ intercalation polymerization of aniline inside the expanded graphite. It was further proved that there existed special hybridizing interactions between the N atoms on PANi and the π-electron on graphene. A series of gradient experiments were designed to determine the key factors affecting the intercalation exfoliation of expanded graphite. Aniline cation with 0.10-0.12 mol/L was found to be more favor to make the intercalation.2. Natural graphite was also successfully intercalated by aniline cation, and uniform graphene/polyaniline hybrids were obtained through a following polymerization. The process of natural graphite’s separation and the intercalation polymerization were analysized by experiment accompanied with theroretical calculation. The electron localization fuction of aniline and aniline cation were compared by appling the DFT study in Gaussian 09. The results indicated that N atoms of aniline cation owned stronger electron delocalization, making them easier to react with the n electrons on the graphite layers. The stable configuration of intercalated bilayer graphene structures could be obtained using the Dmol3 package under Materials Studio. The corresponding results theoretically proved the graphite could be effectively intercalated by ANi cation. Based on theoretical calculation and experimental study, detailed cation pre-intercalating graphite mechanism, process mechanism for the separation of graphite by intercalation polymerization were also proposed.3. The in-situ intercalation polymerization technology was expanded by using pyrrole as an intercalative agent, and graphite oxide as the carbon resource. The here pyrrole could also separate the graphite oxide by intercalation polymerization to obtain hierarchical graphene oxide/polypyrrole composites. Chemical hybridizing groups of CO--HN were formed inside the graphene oxide layers during the exfoliation of graphite oxide, resulting in a new kind of graphene oxide based composites with highly crumpled structures. The unsymmetrical CO…HN groups between-NH2+ in polypyrrole and -COOH on graphene oxide could lead to highly crumpled intercalated polarization interfaces.4. The graphene/conducting polymers synthesized by the intercalation polymerization exhibited excellent electromagnetic absorption with stronger absorption and wider bandwidth. The graphene/polyaniline hybrid showed a breakthrough in improvement of electromagnetic loss. The optimal absorption peak could reach -36.9 dB at 10.3 GHz and the bandwidth was 5.3 GHz (from 8.2 to 13.5 GHz). Meanwhile, polypyrrole intercalated graphite oxide could bring wider bandwidth covering X-band and Ku-band (absorption bandwidth over 6 GHz). The optimal RL value could be up to -58.1 dB (12.4 GHz). Besides, electromagnetic loss enhancement mechanisms based on intercalation hybridization and three-dimentional polarization network were also proposed.5. In order to regulate the intercalation hybridization and the polarization network, thus further improve the electromagnetic properties, nanodiamond was introduced into the intercalated hybrids. It was found that the agglomeration of nanodiamond and its densely distributing on the graphene surface could seriously reduce the electromagnetic loss charateriastics. Therefore, the design of ANi+ dispersing nanodiamond and an on-site polymerization for preparation of well dispersed nanodiamond/polyaniline composites was proposed. The nanodiamond was non-gap combined with polyaniline in the composites. And the hybrids displayed significant improvement in electromagnetic loss. |
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