Study On The Preparation Of Polyaniline@Graphene Hybrids By Intercalation Polymerization And Their Functional Regulation

Studying on graphene-based hybrids is important for the functional regulations and applications of graphene.But the hybrids synthesized by existing methods always contain some uncontrollable defects on graphene layers,decreasing the performance of hybrids and disturbing related scientific researches.In situ intercalation polymerization provides a convience method for the preparation of graphene and its hybrids.The synthesized polymer@graphene hybrids ensure the integrate structure of graphene.Besides,the two-dimensional confined space constructed by graphene layers may also influence the polymerization process.Thus,the structure and properties of the synthesized hybrids seems to be novel and attractive.However,the mechanism of the intercalation polymerization is not clearly,leading to some difficulties in the stuructural regulations of the synthesized hybrids as well as their performance studies.This work focus on some key issues of intercalation polymerization involving the intercalation of aniline cations(ANI⁺)into the interlayers of graphite.The synthesic methods of intercalation polymerization and corresponding mechanism are studied.The structure of the synthesized hybrids,and their functional applications are further investigated.The major results are presented below.(1)In situ spectroscopy and other structural characterizations are applied together with first principle simulation for investigating the structural changes of polyaniline(PANI)during in situ intercalation polymerization.The results indicate that the reaction is divided into two major stages.The first stage(0-4 h after initiating the polymerization)majorly involves the exfoliation of graphite and the formation of polyaniline@graphene(PANI@GE)hybrids.After 4 h of reaction,the graphite has been exfoliated into graphene and form uniform hybrid structures.The p-?and?-?interactions between intercalated PANI molecule and graphene layers induce the electron clouds transferring between fragments,influencing the electronic states of the PANI.A longer reaction time just leads to massive aggregations of PANI.(2)Intercalation polymerization of ANI⁺ are achieved by the de-intercalation of ammonium persulfate/sulfuric acid(APS/H₂SO₄)from the interlayers of graphite.The reaction process are tracked,and the resulted hybrids are carefully charizated for clarifying the reaction mechanism.The de-intercalated APS/H₂SO₄ contacts with ANI⁺solution,initiating the polymerization at interfaces.The synthesized PANI expands the graphite edges and then greets more ANI⁺intercalating into the interlayers.The finally synthesized PANI-intercalated graphite(PANI-IG)contains oriented PANI molecules with the thickness of single atom,together with APS/H₂SO₄ domains sealed in the interlayer of graphite.(3)Simulations based on molecule dynamic and density functional theory are applied to investigate the adsorption and intercalation of ANI⁺,as well as the interactions between ANI⁺and graphene.The results indicates that the ANI⁺adsorb on the surface of graphite by electrostatic forces,leading to the weakening of interactions between graphene layers.The ultrasonication during intercalation process breaks the ANI⁺hydrated cluster formed by hydrogen bond,not only reduce the steric hindrance for intercalating,but also releases the positive charge in ANI⁺.Moreover,ultrasonication provides ANI⁺kinetic energy to overcome the interlayer interactions,which benfients for the intercalation.(4)Twisted graphene are controllable synthesized by the de-intercalation induced ANI⁺polymerization,and simulations are used to explain the twist mechanism.When polymerizing in the interlayer of graphite,the intrinsic torsional configuration of PANI molecules drives the rotation of adjacent layers,leading to the twist of graphene layers.By controlling the growth kinetics of PANI,the controllable twist angles from 2.2°to14.5°are achieved.Furthermore,the superlattice induced by the twists between graphene layers and its further hybridization with PANI molecules result in tunable band structure and carrier mobilities.(5)Microwave absorption(MA)performance of PANI@GE hybrids with different strcutral characterizations are investigated,and its enhancement mechanism are discussed basing on their structure characterizations and electromagnetic parameters.The suffient exfoliation of graphene layers and appropriate hybridization of PANI molecules not only improve its impedance matching but also enhance the polarization relaxation.The hybridization of PANI molecules induce the polarization of graphene during in situ intercalation polymerization.Thus the polarized graphene molecules display high efficient consumption of incident microwave energy by structural resonance.Therefore,the optimized intercalation hybrids exhibit a superior MA ability.The RL value is down to-64.3 d B(at 10.1 GHz)with the RL bandwidth of-10 d B being 5.1 GHz(from 8.6 to 13.7 GHz),indicating a broad and strong absorption.