Received: 2 June 2008, Revised: 2 September 2008, Accepted: 18 September 2008, Published online in Wiley InterScience: 17 December 2008 Composite thin films of poly(phenylene oxide)/poly(styrene) and PPO/silver via vapor phase deposition I. S. Bayer a * , A. Biswas b , A. Tripathi c , D. K. Avasthi c , J. P. Singh d and C. M. Megaridis e We report fabrication of thin (100300 nm) poly(phenylene oxide) (PPO) films and their composites with poly (styrene) (PS) and silver (Ag) nanoparticles using a one-step electron beam-assisted vapor phase co-deposition technique. Surface morphology and the structure of the deposited polymer thin film composites were characterized by FTIR, Raman, X-ray spectroscopy, and contact angle measurements. As-deposited PPO films and PPO/Ag composites were of porous nature and contrary to solvent casting techniques were free from nodular growth. In the case of PPO/PS thin film polymer composites, however, film morphology displayed nodular growth of PPO with nodule diameters of about 200 nm and height of approximately 50 nm. Unique morphological changes on the porous PPO thin film surface were noticed at different Ag filling ratios. Further, the capacitance of PPO/Ag composites (<16 wt%) were measured under radio-frequency conditions and they were functional up to 100 MHz with an average capacitance density of about 2 nF/cm 2 . The fabricated PPO-based composite systems are discussed for their potential applications including embedded capacitor technology. Copyright ß 2008 John Wiley & Sons, Ltd. Keywords: poly(phenylene oxide); vapor phase deposition; polymer–metal composites; polymer composites; capacitors INTRODUCTION Polymer-based nanocomposites have recently emerged as very important material systems for a variety of advanced technology applications. These include among others, miniature electronics (e.g. embedded passive components) and membrane technol- ogies. [1] Embedding surface-mounted discrete passives into a circuit board structure can reduce the size of an electronic system considerably. This can be achieved by utilizing the advantages offered by the polymer–polymer and polymer–inorganic com- posite thin film systems. [2–7] For instance, in high frequency (>1 MHz) applications, easy processing and flexibility offered by polymers combined with high dielectric properties of sub-micron metallic and/or ceramic particles and the possibility of elimination of solder connections have simulated intense research in developing nanoscale novel polymer–polymer and polymer–inorganic composites. [8,9] However, design and imple- mentation of polymer composite passive structures are difficult as very few polymer resins with high glass transition tempera- tures such as polyimide can withstand the elevated temperatures of printed circuit board assembly process. Furthermore, ferro- electric polarization losses which contribute toward increasing tangent loss (tand) of the ferroelectric-based capacitor devices, usually limit their applications in the high frequency region. Polymer–metal nanocomposites with suitable material structures produced near the percolation threshold of the metal volume filling have been studied as alternative material systems for embedded capacitor applications. [8] Increasing the metal volume filling in the polymer near the percolation threshold can dramatically enhance the dielectric constant of the composite. [8,9] However, such composites also give rise to electron tunneling probabilities which eventually produce high leakage in the capacitor device. One solution is to keep the metal volume filling below the percolation threshold while choosing a suitable (www.interscience.wiley.com) DOI: 10.1002/pat.1315 Research Article * Correspondence to: I. S. Bayer, Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, IL 61801, USA. E-mail: ibayer1@illinois.edu a I. S. Bayer Department of Aerospace Engineering, University of Illinois at Urbana- Champaign, IL 61801, USA b A. Biswas Department of Physics and Astronomy, University of Oklahoma, OK 73019, USA c A. Tripathi, D. K. Avasthi Inter-University Accelerator Centre (IUAC), New Delhi 110067, India d J. P. Singh Department of Physics, Indian Institute of Technology, New Delhi 110016, India e C. M. Megaridis Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, IL 60607, USA Contract/grant sponsor: DMEA; contract/grant number: H94003-05-2-0501. SPAWAR-DARPA; contract/grant number: N66001-07-1-2001. Contract/grant sponsor: NSF CAREER; contract/grant number: CHE-0239803. Contract/grant sponsor: NSF MRSEC; contract/grant number: DMR-0520550. Polym. Adv. Technol. 2009, 20 775–784 Copyright ß 2008 John Wiley & Sons, Ltd. 775