Journal of Research Updates in Polymer Science, 2019, 8, 21-26 21 E-ISSN: 1929-5995/19 © 2019 Lifescience Global Cationic Polymerization Induced by Tris-(p-bromophenyl) Amine Cation-Radical Salts Ideisan I. Abu-Abdoun * Department of Chemistry, University of Sharjah, Sharjah P.O. Box: 27272, UAE Abstract: Substituted triphenylamine cation radical salts having anions of the type SbF6 - , PF6 - , BF4 - and SbCl6 - , were prepared and used to initiate cationic polymerization of cyclohexene oxide (CHO), tetrahydrofuran (THF), and N-vinyl carbazole (NVC), thermally in dichloromethane at room temperature. Experimental results are presented to show the effects of salt counter ion, concentration, and polymerization conditions on the yield and the molecular weight of the obtained polymer. THF polymerization was enhanced by photolysis of the reaction mixture for short time. A general mechanism for the polymerization by cation-radical salts of substituted triphenylamine is proposed. Keywords: Tris-(p-bromophenyl) amine. Cation radical salts. Cationic polymerization. N-vinyl carbazole. Cyclohexene oxide. Tetrahydrofuran. 1. INTRODUCTION Great effort has been devoted in developing systems that may initiate the polymerization processes through various known mechanisms. Cationic polymerization is widely applicable for both vinyl and ring opening polymerizations giving place to many studies of both academic and industrial interests [1]. Thermally stable onium salts, such as diaryliodonium [2], triarylsulfonium [3], phosphonium and arsonium salts [4,5] in the presence of low nucleophilic complex metal halide anions are well established photo initiators for cationic polymerization. It has been suggested that photolysis of triarylsulfonium and diaryliodonium salts results in the cleavage of a carbon - sulfur or a carbon - iodine bond to yield reactive radical cation as shown in the equations (1&2) below: Ar 3 S + X - ------------> Ar 2 S . + X - + Ar . (1) Ar 2 I + X - ----------------> Ar .+ X - + Ar . (2) Accordingly, the interaction of the produced cation radical with the monomer is expected to produce the initiating species. Recently, we reported on the cationic polymerization of epoxide and vinyl monomers initiated by cation radical salts of phenothiazine derivatives (salt 1) [5], and N, N, N,N-tetraphenyl-p- phenelenediamine (salt 2) [6]. *Address correspondence to this author at the Department of Chemistry, University of Sharjah, Sharjah P.O. Box: 27272, UAE; Tel: 06-505 3810; Fax: 06-505 3820; E-mail: abuabdoun@sharjah.ac.ae Salt 1 Salt 2 Triphenylamine derivatives are well known hole transport materials with very high charge transport mobility, which are frequently used in light emitting devices and organic displays [7,8]. Tris-p-substituted triphenylamine are readily oxidized to form stable cation- radicals, which have been shown to have a useful role as one electron oxidizing agents for the organic molecules, especially as the intense visible and ESR spectra of these salts provide convenient probes for monitoring reactions [9,10]. This paper describes the synthesis of tris-(p- bromophenyl) amine cation radical salt (structure 3), and its use in cationic polymerization of selected epoxide and vinyl monomers at room temperature. Salt 3 X = SbF6, PF6, BF4, SbCl6 2. EXPERIMENTAL 2.1. Materials Tris-(p-bromophenyl) amine was obtained by a known procedure [11,12]. Monomer cyclohexene oxide, h