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  1. 1. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537 A Unique Approach To Prepare Poly (Acrylamide –Co-Itaconic Acid) /Graphite Composite Polymer For Electrical Conducting Properties. S .K. Bajpaia*, S. Awasthib* And Abhishek Dubeyb a. Polymer Research Lab, Dept.of chemistry, Govt. Model Science College, Jabalpur (M.P)-482001, India b. Dept.of Physics, Govt. Model Science College, Jabalpur (M.P)-482001, India.Abstract In this work a pH-sensitive fiber–reinforced composites with different fiberpoly(acrylamide-co-itaconic acid)/ graphite loadings based methyl methacrylate/ poly(methylcomposite hydrogel is prepared by free radical methacrylate) (MMA/PMMA). In a work by Fan etinitiated polymerization of monomers al.[8], few-layered graphene sheets, synthesized byacrylamide(Am) and itaconic acid(IA) in the direct current arc-discharge method using NH3 aspresence of settled graphite(Gt) particles using one of the buffer gases were dispersed in chitosanN,N’-methylene bisacrylamide(MB) as cross /acetic acid solutions to prepare films. The filmslinker in aqueous medium. The SEM analysis were tested for mechanical properties andrevealed almost uniform distribution of grafite biocompatibility. In addition to the above mentionedparticles within the polymer matrix.For the same conjoint instrumental techniques to prepareamount of graphite, the conductivity of hydrogel conducting polymer composites, there have alsocomposite was observed to increase and later on been relatively simpler methods proposed todecrease with amount of cross linker (MB) and synthesize conducting polymer composites. Formonomers IA and Am. example, Lin et al.[9] have reported synthesis of polyacrylate/ graphite hydrogel by a simpleKeywords: Graphite, , conductivity, cross linker. approach which involves free–radical initiated polymerization of potassium acrylate in the presenceINTRODUCTION of graphite particles pre-dispersed in the reaction Recently, they have been considerable mixture. However, there exists some uncertaintyefforts made to prepare conducting polymers(CP) for regarding the almost homogeneous/ uniformusing in a variety of applications such as fuel cells, distribution of graphite particles within the polymersuper capacitor, dye sensitive solar cells and re- network formed because the chances of settlingchargeable lithium batteries[1-2]. There are several down of graphite particles dusting the course ofreports which describe synthesis of conducting polymer formation can not be completelypolymers using various types of chemical species of and inorganic origin such as aniline, pyrrole, In the present work, we have developed acopper, carbon etc [3-4]. However, looking to the pH-sensitive polymer/ graphite composite hydrogelexcellent electrical conducting property of carbon using an almost diffrent approach which totallybased compounds like graphite and graphene, the eliminate the chances of agglomeration or non-current research works have mainly focused on these uniform distribution of graphite within the polymermaterial to prepare conducting polymers. In fact, a networks.variety of strategies have been followed to prepareconducting polymer composites. Recently, Fouad et EXPERIMENTALal.[5] have reported synthesis of high density Monomers acrylamide (Am) and itaconicepolyethylene/graphite nano composites using melt acid (IA), the cross linker N,N’-methyleneblending in a co-rotating intermeshing twin screw bisacrylamide (MB), the initiator potassiumextrude. One-pot synthesis of conducting graphene- persulfate(KPS) were purchased from Hi Mediapolymer composite has been recently reported by Chemicals, Mumbai, India .The graphite microEswaraiah et al.[6].The simultaneous reduction of powder (Gt), having a specific surface area largergraphite oxide, melting of the polymer and than 80m2g-1 and an average particle size smallerembedding of reduced graphite oxide nano flacks in than 1.8x10-6m was purchased form Merckpolymer offer a new way of synthesizing graphene/ Chemical, Mumbai, India and was dried at 60 °C forpolymer composite. Similarly, Segerstrom et 4h prior to use. The monomer (Am) was re-al[7].carried out a study to determine water sorption, crystallized in methanol to remove the inhibitor .Thewater solubility, dimensional change caused by de-ionized water was used throughout thewater storage, residual monomer ,and possible investigations.cytotoxic effect of heat-polymerized carbon-graphite 1532 | P a g e
  2. 2. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537Preparation of p(Am-co-IA)/Gt composite values, obtained, were represented graphically as The composite was prepared by free radical shown is Fig.3. All data points joined yielded ainitiated aqueous polymerization of Am and IA in horizontal straight line thus indicating that all thethe presence of cross linker( MB)within the settled sample had almost the same density.graphite column. For example, in a test-tube, 14.06mili mol of Am, 384.3 micro mol of IA, 518.90 SEM analysis of compositemicro mol of crosslinker MB and lastly 295.9 micro The novelty in the proposed study is tomol of initiator KPS was dissolved in the above ensure the uniform distribution of graphite particlessequential manna is distilled water and the final within the polymer matrix. To confirm this SEMvolume was made up to 5.0 ml. To this ,a per- image of polymer/graphite composite was recordedweighed quantity e.g. 1.7g of graphite powder was as shown in Fig.4. It can be seen that there is fairlyadded slowly and carefully and then the above uniform distribution of particles within the polymermixture was shaken vigorously for 5 min and thus establishing the superiority of this method.allowed to stand till all the graphite powder wassettled. The test-tube was now placed is an electric Effect of crosslinker on conductivityoven (Tempstar,India) at 70°C for a period of In order to study effect of crosslinker2h.After the polymerization was over, the test-tube concentration on conductivity of resultingwas taken out , broken and the cylindrical P(Am-co- composites , we prepared number of polymer/ GtIA)/Gt hydrogel composite was taken out, washed composites, containing different amount ofwith distilled water and then cut into slices each one crosslinker MB, in the range of 129.72 to 648.63almost 2mm thick. The circular discs were micro mol and measured their conductivity usingequilibrated in water for 12h to remove the un- four probe experiment. The results, as shown inreacted salts, then finally dried till they attained Fig.5 reveal that electrical conductivity of compositeconstant weight. The Fig.1 shows the optical increases with crosslinker concentration attains anphotograph of plain p(Am-co-IA) and p(Am-co- optimum value of 279.16 S/cm at the crosslinkerIA)/Gt composite discs. concentration, of 389.18 micro mol and then it begins to decrease with further increase in MBMeasurement of electrical conductivity content. The observed findings may be explained as The electrical conductivity of composites follows: When the amount of crosslinker MB isdiscs measured using four probes method Five quite low, the loosely bonded three dimensionalmeasurements were made and average values are crosslinked network is formed, which is quite unablereported. to put entrapped charcoal microparticles intact, thus resulting in low conductivity of the polymerRESULTS AND DISCUSSION composite. As the amount of crosslinker increased,Preparation of p(Am-co-IA)/Gt composite : more and more tightly crosslinked network is As mentioned in the section introduction formed within the polymer matrix , thus holding thethe preparation of polymer/ graphite composite by entrapped graphite particles more intact. This causesfree-radical induced polymerization in the presence an increase in the conductivity and finally it attainsof dispersed graphite particles is a commonly an optimum value. However, as the concentration ofadopted method. But the non-uniform distribution of crosslinkers is increased further, the number ofgraphite particles, on a micro scale level, may result crosslinkes increase and this reduces the free spacein formation of gel composite having un-even available among the three-dimensional crosslinkedphysico-chemical and other related properties along segments and so the space available is small enoughthe polymer network. However, in the present study, as compared to the size of the micro sized particles.the polymerization of acrylamaid and itaconic acid This is turn causes the weakening of the inter-takes place within the aqueous phase which is connectivities among graphite particles, thus causingpresent within the settled graphite column. a decrease inelectrical conductivity. Almost similarTherefore, the chances of inhomogeneous result have also been reported elsewhere[3].distribution of Gt particles within the polymernetwork are almost nil. Fig.2 shows the overall Effect of IA content or conductivityscheme of formation of polymer/ graphite The effect of IA content in the polymer/composite. In order to ensure the uniformity in the graphite composite on the electrical conductivitygraphite particles distribution along the polymer was investigated by measuring conductivity ofmatrix, we carried out an experiment. The volume of various samples, containing varying moles of IA invarious composite discs, obtained from same the feed mixture, in the range of 230.59 to 1383.55sample, was determined accurately using heptane as micro mol as shown in Fig.6. The results indicateda non-solvent Then mass of each composite disc was that with the increase of IA content in the composite,measured accurately and finally density of all the electrical conductivity continues to increase, attainssamples was calculated using the density = an optimum value of 193.43for 1152.95micro mol ofmass/volume relationship. Finally, all the density IA, and then it begins to decrease with further 1533 | P a g e
  3. 3. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537increase in content of monomer acid. The results 4. Lin,J.; Tang,Q.; Wu,J. Reactive and Funct.obtained may be explained on the basis of the fact Polymer 2007,67,489.that initially when IA content is low, the graphite 5. Tang,Q.; Wu,J.; Sun,H.; Lin,j.; Fan,s.;particles that are present within the three Hu,D. Carbohydrate polymers 2008,dimensional networks are not much intact or have 74,215.insufficient inter-particles connectivity. As the IA 6. Fouad, H.; Elleithy, R. J. Mech , Behav.content increase, the presence of carboxylic acid Biomed, Mater . 2011, 49(7),1376.groups causes an enhancement in the inter-segmental 7. Eswarajah,V.; Balasubramaniam,K.;hydrogen bonding interactions which produce Ramprabhu,S. Nanoscale2012,4(4),1258.additional crosslinks within the polymer networks. 8. Segerstrom,S.; Sandbargh-Englund,G.;As a results, the graphite particles have better Ruyter,E.L. Eur. J. Oral Sci. 2011, 11a(3),connectivity with each other, thus resulting in 246.enhancement in the electrical conductivity of the 9. Fan, H; Wang, L.; Zhao,K.; Shi , Z. ; Jin ,composite. However, beyond 193.43 micro mol Z. ;and Ge, Z. Biomacromolecule ,2011,concentration of IA, the further rise in IA content 11(9), 2345.causes the mesh size of the polymer networksufficiently small enough so that the micrometer Captionssized graphite particles are not well occupied in the Figure 1. Optical photograph of (A) poly(Am-co-IA)three dimentional crosslinked networks and hence and (B) poly(Am-co-IA)/Gt composite.begin to lack of connecting channels. Finally, this Figure 2. Schemes showing formation of poly(Am-result in decrease in the conductivity of the polymer co-IA)/Gt composite.of composite. Figure 3. Test for uniform distribution of graphite Similarly, the conductivity of powder within the polymer matrix.polymer/graphite gel showed similar trend when Fig.4 SEM image of polymer/graphite compositecontent of other monomer Am was increased (Please Figure 5. Effect concentration of MB in the feedsee Fig.7). This can also be explained as follows : mixture on electrical conductivity of the poly(Am-when amount of Am is sufficiently low, these is not co-IA)/Gt composite.enough network formation and this results is Figure 6. Effect of monomer IA concentration in theincapability of crosslinked segments to hold the feed mixture on electrical conductivity of themicro sized graphite particles almost intact, thus poly(Am-co-IA)/Gt composite.causing low conductivity .On increasing the Figure 7. Effect of Am concentration in the feedmonomer content ,fairly high degree of mixture on electrical conductivity of the poly(Am-polymerization occurs with fairly dense network co-IA)/Gt composite.This keeps the graphite particles almost intact andallows optimal conductivity. However, whenAm content is further increased , the polymerfraction in the composite increases . Since Am isnonionic in nature , it causes a decrease is theconductivity of the resulting composite material.CONCLUSION From the above steady it may be concludedthat poly (Am-co-IA)/ Gt composite , produced byfree radical initiated polymerization of Am and IAin the presence of pre-settled graphite powderresults in formation of composite with uniformlydistributed Gt particles throughout the polymermatrix.. It conductivity changes with amount ofcrosslinker MB ,ones monomer Am and IA presentin the feed mixture.References 1. Lan, z.; Wu, J. H.; Wang, D. B.; Wao, s. c.; Lin, J. M. & Huang, V. F; Solar Energy 2006, ,90,1483. 2. Kato,T; Okazaki,A; Hayase,S. J.photobiology A:chemistry 2006, 179,42. 3. Lin,J.; Tang,Q.; Wu,J; Hao,S. Reactive and Funct. Polymer 2007,67,275. 1534 | P a g e
  4. 4. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537 Fig.1 Fig.2 Fig.3 1535 | P a g e
  5. 5. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537 Fig.4 Fig.5 Fig.6 1536 | P a g e
  6. 6. S .K. Bajpai, S. Awasthi, Abhishek Dubey/ International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 Vol. 2, Issue 5, September- October 2012, pp.1532-1537 Fig.7 1537 | P a g e