Polymer Communication Synthesis of polysilane±acrylamide copolymers by photopolymerization and their application to polysilane±silica hybrid thin ®lms Yukihito Matsuura a , Kimihiro Matsukawa a, * , Ryuichi Kawabata b , Nobuyuki Higashi b , Masazo Niwa b , Hiroshi Inoue a a Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan b Department of Molecular Science and Technology, Faculty of Engineering, Doshisha University, 1-3 Miyakodani, Tatara, Kyotanabe, Kyoto 610-0321, Japan Received 5 September 2001; received in revised form 12 October 2001; accepted 15 October 2001 Abstract Various polysilane±acrylamide block copolymers have been prepared from photopolymerization of acrylamide-type monomers using polymethylphenylsilane) PMPS) as a macro-photo-radical initiator. The acrylamide block in the copolymers improved the hydrophilic property of PMPS. These PMPS±acrylamide block copolymers have been applied to formation of PMPS±silica hybrid thin ®lms via sol±gel reaction. Homogeneous and transparent PMPS±silica hybrid thin ®lms were obtained from a few PMPS±acrylamide block copolymers. It was found for these hybrid thin ®lms based on hydrogen bonding formation between amide group and silanol group. The surface properties of hybrid thin ®lms were evaluated by water contact angle measurement, scanning electron microscope SEM), and atomic force microscope AFM) images. q 2001 Elsevier Science Ltd. All rights reserved. Keywords: Polysilane; Polysilane±acrylamide block copolymer; Organic±inorganic hybrid thin ®lm 1. Introduction Recently, many types of organic±inorganic hybrid materials have been developed because of their interesting properties, for example, molecular homogeneity, transpar- ency, rigidness, and various optical functionalities [1]. Especially, in a ®eld of optics, there are much interest to apply these hybrid materials to planar waveguide as one of examples, because the refractive index of these hybrid mate- rials can be controlled with the variation of composition [2]. These properties are based on the network structure of inor- ganic matrix linking to organic domains through chemical bonding. Chujo et al. have reported various hybrid materi- als, which consisted of a wide variety of chemical bonding states [3,4]. They proved that even hydrogen bonding inter- action or p± p stacking interaction give the hybrid materials homogeneity and high resistivity to solvent [5]. We have prepared polysilane±silica hybrid thin ®lms by using polysilane±acrylic block copolymers as starting materials for sol±gel reaction with tetraethoxy orthosilicate TEOS) [6]. These hybrid thin ®lms were composed of a wide range of polysilane and silica ratios without phase separation and showed wide refractive index changes with different composition ratio or UV irradiation [7]. These polysilane±silica hybrid thin ®lms consisted of covalent bonding Si±O±Si) formed by hydrolysis and condensation between the polysilane±acrylic block copolymers and TEOS. In this paper, we describe the synthesis of polysilane± acrylamide block copolymers by photopolymerization of acrylamide monomers using polymethylphenylsilane) PMPS) as a macro-photo-radical initiator. Furthermore, we tried to prepare PMPS±silica hybrid thin ®lms using these copolymers and TEOS through sol±gel reaction. Transparency, homogeneity, and surface properties of the polysilane±silica hybrid thin ®lms thus prepared were also evaluated. 2. Experimental 2.1. Synthesis We used the following vinyl monomers Fig. 1) for the photopolymerization: N,N-dimethyl acrylamide DMAA), N,N-diethyl acrylamide DEAA), acryloylmorpholine ACMO), N,N-dimethylaminopropyl acrylamide DMA Polymer 43 2002) 1549±1553 0032-3861/02/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved. PII: S0032-386101)00693-0 www.elsevier.com/locate/polymer * Corresponding author.