Synthesis and characterization of conjugated polycyanamide with ultrafast optical Kerr effect Xiongyan Zhao a , Xiao Hu a, * , Yuankang He b , Huiying Chen b a School of Materials Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore b Institute of Polymer Science, College of Chemistry, Peking University, Beijing 100871, People’s Republic of China Received 11 January 2001; received in revised form 4 November 2001; accepted 6 November 2001 Abstract The conjugated polycyanamide (PCN) was successfully prepared by radio frequency glow discharge techniques. The structure of PCN was characterized by means of Fourier transform infrared (FT-IR), UV–Visible absorption spectra and X-ray photoelectron spectroscopy (XPS), which revealed that extensive conjugation was formed in the polymer PCN. The subpicosecond time-resolved optical Kerr effect (OKE) was used to measure the third-order optical nonlinearity of PCN samples. For the first time, an ultrafast response and nonresonant optical Kerr effect of plasma polymer PCN was observed. D 2002 Elsevier Science B.V. All rights reserved. Keywords: Cyanamide; Plasma polymerization; Optical Kerr effect (OKE); Conjugated polymer 1. Introduction Commercial and military interest in nonlinear opti- cal materials is being driven by the development of fiber optics, laser diodes optical information storage, optical signal processing and optical computing [1,2]. Conjugated polymers, with strong delocalization of electrons contributing to the large and fast optical res- ponse, have provoked increasingly focused interests for their great potentiality for high-technology appli- cations [3,4]. Polynitrile is one of the conjugated polymers that was found to exhibit large third-order susceptibility and hyperpolarizability [5] as well as excellent and reproducible electrical bistability pro- perty [6]. However, the progress on the conjugated polynitriles has been hampered by the fact that the polymerization of nitrile monomer to the correspond- ing CMN conjugated polymer is very difficult and cannot occur under conditions typical for polymer- ization of vinyl and acetylenic monomers [7,8]. Plasma polymerization is now gaining recognition as an important technique for the preparation of entirely new kinds of polymeric materials, which are hardly possible to obtain and often suffer from many disadvantages such as instability in air and poor so- lubility in common organic solvents by the conven- tional polymerization methods. Here we report the preparation and characterization of plasma-polymer- ized cyanamide as well as its third-order optical non- linearity. 0167-577X/02/$ - see front matter D 2002 Elsevier Science B.V. All rights reserved. PII:S0167-577X(02)00382-8 * Corresponding author. Tel.: +65-790-4610; fax: +65-792- 6559. E-mail address: asxhu@ntu.edu.sg (X. Hu). www.elsevier.com/locate/matlet August 2002 Materials Letters 55 (2002) 300 – 303