Synthesis and Study of CdS Nanoparticle- Doped Poly(1,4-dihexyloxybenzene) a Gouri Sankar Paul, Pranjol Jyoti Sarmah, Parameswar Krishnan Iyer, * Pratima Agarwal * Introduction Over the last 15 years, a significant amount of research activity has focused on semi-conducting (conjugated) polymers like polyacetylene (PA), poly( para-phenylene) (PPP), poly( para-phenylenevinylene) (PPV), polythiophene (PT) and their derivatives because of their potential applications in light-emitting devices, [1–4] photovoltaic cells, [5,6] biosensors, [7] organic lasers, [8] rechargeable bat- teries, [9,10] all polymer field effect transistors, [9] non-linear optics, [11] the separation of gases [12] and ion exchange membranes [13] combined with their attractive material properties, such as low weight and ease of processing. The conductivity of these polymers, which are otherwise highly insulating, can be enhanced by several orders of magnitude by doping with metals and other compounds, making them useful for device applications. However, most of these doped polymers often have limitations like poor stability of physical and chemical properties in different environments. Doped PPP, on the other hand, has been found to be highly thermally stable, and resistant to oxidation and chemical degradation, making it more useful for device applications. Besides being stable, PPP has several other advantages, such as a simple rigid rod-like structure composed of phenylene rings connected between para(1,4) positions, high tensile strength, high compressive strength, high electrical conductivity on doping, [14–17] a wide conductivity range and high quan- tum yield in electroluminescence. [18] Importantly, PPP has Full Paper A simple, economical and high yielding method to prepare poly(1,4-dihexyloxybenzene), an alkylated derivative of poly( para-phenylene) (PPP), is reported. We further prepared a com- posite of poly(1,4-dihexyloxybenzene) and CdS nanoparticles and studied their structural, optical, stability and transport properties. It was observed that the conductivity of poly(1,4- dihexyloxybenzene) increased by several orders of magnitude when doped with CdS nano- particles. Similarly, CdS nanoparticle- doped PPP showed higher thermal stability, when compared to the neat polymer. As these composites could be processed in the same way as organic polymers, they would find applications in many low-cost optoelectronic devices. G. S. Paul, P. Agarwal Centre for Energy, Indian Institute of Technology Guwahati, Assam 781039, India E-mail: pratima@iitg.ernet.in P. J. Sarmah, P. K. Iyer Department of Chemistry, Indian Institute of Technology Guwahati, Assam 781039, India Fax: þ91 361 258 2749; E-mail: pki@iitg.ernet.in P. Agarwal Department of Physics, Indian Institute of Technology Guwahati, Assam 781039, India a : Supporting information for this article is available at the bottom of the article’s abstract page, which can be accessed from the journal’s homepage at http://www.mcp-journal.de, or from the author. Macromol. Chem. Phys. 2008, 209, 417–423 ß 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/macp.200700385 417