Synthesis of poly[1,1,1,3,3,3-hexafluoro-2-(pentafluorophenyl)propan-2-yl methacrylate]: Thermal and optical properties of the copolymers with methyl methacrylate Dingying Zhou a , Yasuhiro Koike b , Yoshiyuki Okamoto a, * a Polymer Research Institute, Polytechnic University, 6 Metrotech Center, Brooklyn, NY 11201, USA b Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan Received 30 September 2007; received in revised form 14 November 2007; accepted 20 November 2007 Available online 11 January 2008 Abstract Poly[1,1,1,3,3,3-hexafluoro-2-(pentafluorophenyl)propan-2-yl methacrylate (I)] was synthesized, and the copolymers of the monomer I with various compositions of methyl methacrylate (MMA) were prepared and characterized. The glass transition temperature values obtained for the copolymers were between 120 and 150 8C. The refractive indices of the copolymers were in the range of 1.4350–1.4872 at 532 nm. They were thermally stable (up to 297–323 8C), and their water absorptive properties were greatly decreased, compared with pure PMMA. # 2007 Elsevier B.V. All rights reserved. Keywords: Co polymerization; Fluorinated methacrylate; Water absorption; Thermal property; Optical property; Dipole–dipole interaction 1. Introduction Poly(methyl methacrylate) (PMMA), a commercially available polymer, is produced in large quantities, demonstrates high light transmittance and provides excellent resistance to both chemical and weather corrosion [1]. These properties, coupled with low manufacturing cost and easy processing, make PMMA a valuable substitute for glass in optical device applications [2]. However, the major disadvantages of PMMA, such as its relatively low glass transition temperature (T g ) (around 100 8C) and high water absorption, limit its utility for optical electronic applications [3,4]. Since introducing fluorine atoms can dramatically improve the thermal and optical properties and water absorption of the polymer, Boutevin’s group and our group have independently prepared fluorine- substituted phenyl methacrylates (II) and their polymers [5,6]. Because the refractive indices of MMA and the fluorine- substituted monomers are in a similar range, copolymers of these monomers may not have an increased light scattering [6]. The T g -values of homopolymers of polyfluorinated phenyl methacrylates (II), such as pentafluorophenyl (IIa), tetrafluor- ophenyl (IIb), and p-trifluoromethyl perfluorophenyl (IIc) methacrylates (Fig. 1) were found to be 133, 125, and 135 8C, respectively. Although these fluorine-substituted phenyl metha- crylates yield excellent random copolymers with various compositions of MMA, the T g -values of the copolymers produced were in the range of 90–120 8C [6]. Generally, the T g -values of alkyl and aryl methacrylates are higher than those of acrylates [7–10]. The T g of poly(1,1,1,3,3,3-hexafluoro-2- (pentafluorophenyl)propan-2-yl acrylate was reported as 118 8C [11]. Accordingly the homopolymer’s T g of the methacrylate, having a 1,1,1,3,3,3-hexafluoro-2-(pentafluoro- phenyl)propan-2-yl group, would be expected to be higher than 118 8C. Therefore, in search of a good candidate for POF materials, we have synthesized methacrylate I (Fig. 1) and the T g of the homopolymer was found to be 146 8C. Consequently, the thermal and optical properties of the homopolymer of I as well as the copolymers with various amount of MMA (Scheme 1) have been investigated. 2. Results and discussion Using azobis(isobutyronitrile) (AIBN) as an initiator, homopolymerization of monomer I and its copolymerization with MMA were carried out in bulk. Without a chain transfer www.elsevier.com/locate/fluor Available online at www.sciencedirect.com Journal of Fluorine Chemistry 129 (2008) 248–252 * Corresponding author. Tel.: +1 718 260 3638; fax: +1 718 260 3508. E-mail address: yokamoto@poly.edu (Y. Okamoto). 0022-1139/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.jfluchem.2007.11.011