Indian Journal of Chemistry Vol. 4 1 A, Septembcr 2002, pp. 1789- 1794 Preparation of organic polymer/inorganic oxide conductive composites AI-Nakib Chowdhllry* & J M Arifllr Rahman Departmcnt of Chemistry, Bangladesh University of Engince ring & Tcchnology, Dhaka-1000, Banglad es h and Md . Aminllf Rahman Institute of Gl ass & Cer:lInic Re search & Testin g. BCSIR, Dhaka. Banglades h Received 25 Fehruarv 2002; revised 30 April 2002 Preparation of cond ucti ve compositcs ba sed on organic conducting polymer and inorganic ox idc has been described. The composite materials thus prepared ha ve becn characterizcd by a wide range of experimental techniques including elemental analysis, density mcasuremen t, UV -vis and IR spectroscopy, X-ray and sedimcntometry. Even after incorporating insulating silica, th e compos it es exhibit el ec tri ca l conductivity comparable to that of th e conventional semiconductors. In cont ra st to the bulk polymer, the composit es show relatively superior environmen tal stability when exposed to ambient atmosph ere. The composit es ha vc bee n further c haractcrized for their surf acc area: in thi s co nn ection. adsorption of methylcnc blue on a composite Illatrix has been ex amincd. Electrically conducting organic polymers with TC- conjugated system have been studied extensively for a variety of applications including electrochromic di sp lays, batteries, solar ene rgy conversion etc l -] . Among the polymers studied, polyaniline (PANI) is considered to be a unique one 4 that can be sy nth es ized either chemically or electrochemically as a bulk powder or film, respectively. Although th ese materials are recog nized to be highly promising for technological applications, their intractable and unproce ssa bl e nature and lack of superior environmental and electrochemical stabilities make their practical utilization limited. How eve r, for the effective and wider practical use of the se polymers, significant improvement of mate ri al properties and processab ility is required. Preparation of composites of conducting polymers could be a potential solution to the proces sab ility problem of conducting polymers as well as to enhance the material properties with de sirable physical and mechanical characteristics . One way of making these composites involves synthesizing the conducti ve polymer inside the matrices of conventional polymers us in g chemical s- I) II I h · I tO -14 I .. I as we as e ectroc emlca po ymenzatlon. n addition, studies pertaining to the chemical preparation of conducting po lymer composites without involving any insulating polymer have also b d l S- t7 I h' h . een repone . nti S approac , monomer IS polymerized in the prese nce of inorganic oxide nanoparticles which act as a hi g h surface area colloidal substrate for the precipitating polymer nuclei leading to the formation of polymer-inorganic oxide nanocompo s it e. These studi es were focus ed so lel y on the processability problem of the polymers, although the use of costly commercially purcha sed nanoparticies, such as LUOOX (co lloidal silica, 40% suspension in water) is considered to be a grea t constrain in d ea ling with this method. In the prese nt work, an attempt has been made to prepare organic polymer/silica conductive composites as an alternative new materials to the bulk polymers. The composites thus prepared were also characterized in terms of physical, chemical, optical and electrical properties. Materials and Methods All the chemicals (purchased either from E. Merck, G er many or BOH Ltd ., England) used in this work were of AR g rade and use d as received unless stated otherwise. The monomers - aniline , o- toluidine and 2- chloroaniline were distill ed twice under nitro ge n atmosphere before use. The solutions used through out the experiments were prepared using doubly di st illed water exce pt for the ultraviolet-visible (UV- vis) measurement s where solution of the samp les were made in dimethylformamide (OMF). Aqueous colloidal silica suspension was prepared in the laboratory ju st by beating a mixture of silica particles (Si0 2 powder , 325 mes h) and distilled water with a ho mogenizer for 2 hour s. The resulting dispersion