Dosimetric characteristics of a Radiochromic polyvinyl butyral film containing 2,4-hexadiyn-1,6-bis(n-butyl urethane) A.A. Abdel-Fattah a , Y.S. Soliman a,n , A.M.M. Bayomi a , A.A. Abdel-Khalek b a National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority, P. O. Box 8029, Nasr City, Cairo 11787, Egypt b Faculty of Science, Chemistry Department, Beni-Suef University, Beni-Suef City, Egypt HIGHLIGHTS  A new thin film based on 2,4-hexadiyn-1,6-bis(n-butyl urethane) is developed.  The film is suitable for industrial dosimetry in the 3–150 kGy range.  Overall uncertainty of dose measurements does not exceed 6.9% (2s). article info Available online 31 December 2013 Keywords: Dosimetry Radiochromic film Industrial irradiations abstract A radiation-sensitive compound 2,4-hexadiyn-1,6-bis(n-butyl urethane) (HDDBU) was synthesized, characterized by FTIR spectroscopy, and introduced into a thin polyvinyl butyral film to form a radiation dosimeter for industrial irradiation facilities. The monomer polymerizes under gamma radiation, inducing change in the film spectrum in the range of 200–400 nm. According to XRD spectroscopy, the film contains monomeric HDDBU in a non-crystalline state. The dose response function, radiation sensitivity, and dependences of the response on environmental factors were studied. Uncertainty of dose measurements with the proposed dosimetry system was analyzed in detail. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Conjugated diacetylene monomers are radiation-sensitive mate- rials. When irradiated in the crystalline state, they undergo a topochemical polymerization (1,4-addition reaction) to form inten- sely colored fully conjugated polydiacetylenes (Wegner, 1972; Cao and Mallouk, 1991). The color of polydiacetylenes stems from the extensive delocalization of π-electrons along π-conjugated polymer chains. The color intensifies progressively with increasing absorbed dose (Patel, 1979, 1981). Fig. 1 (a–c) shows a diagram of topochemical polymerization of diacetylene units into π-conjugated polydiacety- lene under ionizing radiation in the crystalline state (Janzen et al., 2006; Hu and Li, 2002). However, there is also crosslinking in the non-crystalline state, as shown in Fig. 1 (d and e) (Hu and Li, 2002). Conjugated diacetylenes have been extensively investigated as dosimetric materials for industrial irradiation processes (Patel, 1981, 2009; Soliman et al., 2013). They are commonly used as radiation-sensitive components in Gafchromic film formulations (Butson et al., 2001; Cheung et al., 2005; Vandana et al., 2011). Generally, conjugated diacetylenes are synthesized by oxidative coupling of the corresponding acetylenes (Hay, 1962). This method is commonly used to prepare diacetylene diol compounds from acet- ylenic alcohols, such as propargyl alcohol (Hu and Li, 1999). Diace- tylene diols can undergo an addition reaction to produce highly π- conjugated and highly radiation-sensitive monomers of diacetylene diurethane (Wegner, 1972; Patel, 1981; Shchegolikhin et al., 2003). A thin solid film with diacetylene polyester of poly(hexa-2,4- diynylene adipate) as a radiation-sensitive component was proposed for monitoring doses in the range of 0.5–60 kGy (Soliman, 2007). Under gamma rays, this component undergoes crosslinking polymer- ization and changes the color of the solid film from faint yellowish- orange to deep orange. The spectrum of the irradiated film features an absorption band in the vicinity of 500 nm with a shoulder near 465 nm. The expanded uncertainty of dose measurements based on this phenomenon was reported to be less than 5.6% at the confidence level 95%. A conjugate diacetylene-diol monomer of 2,4-hexadiyn-1,6- diol was synthesized by oxidative coupling of propargyl alcohol and incorporated into a thin polyvinyl butyral (PVB) film for dosimetry in the dose range of 0.5–65 kGy (Abdel-Fattah et al., 2009). The reported overall uncertainty of dose measurements at 273 nm was under 5% (2s), provided that the contributions from the temperature and humidity effects were not included. A conjugated monomer of 10,12- pentacosadiynoic acid (PCDA) undergoes topochemical solid-state Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/apradiso Applied Radiation and Isotopes 0969-8043/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apradiso.2013.12.023 n Corresponding author. Tel./fax: þ2 02 2671 4166. E-mail address: yasser_shabaan@hotmail.com (Y.S. Soliman). Applied Radiation and Isotopes 86 (2014) 21–27