Preparation and properties of semifluorinated block copolymers of 2-(dimethylamino)ethyl methacrylate and fluorooctyl methacrylates Ha Soo Hwang a , Jae Young Heo a , Yeon Tae Jeong a , Sung-Ho Jin b , Donghyun Cho c , Taihyun Chang c , Kwon Taek Lim a, * a Division of Image and Information Engineering, Pukyung National University, San 100 Yongdang-dong, Nam-gu, Pusan 608-739, South Korea b Department of Chemistry Education, Pusan National University, Pusan 609-735, South Korea c Department of Chemistry and Polymer Research Institute, Pohang University of Science and Technology, Pohang 790-784, South Korea Received 10 March 2003; received in revised form 19 June 2003; accepted 20 June 2003 Abstract Semifluorinated block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(fluorooctyl methacrylates) (PFOMA) were prepared using group transfer polymerisation via sequential monomer addition. Wide ranges of copolymers were obtained with good control over both molecular weight and composition by adjusting the monomers/initiator ratio. The micellar characteristics of the copolymers in water and chloroform were investigated by quasi-elastic light scattering and transmission electron microscopy. The size and morphologies of micelles were greatly influenced by copolymer composition, pH, and temperature. In addition, the solubility of copolymers and the formation of water-in-carbon dioxide (W/C) microemulsions were described in terms of the cloud points. The block copolymers exhibited the excellent ability of stabilizing W/C microemulsions. q 2003 Elsevier Ltd. All rights reserved. Keywords: Block copolymer; Micelle; Semifluorinated copolymer 1. Introduction Semifluorinated block and graft copolymers are of growing interest as membrane for water treatment [1] and emulsifier in liquid and supercritical carbon dioxide [2]. Especially, emulsions consisting of the environmentally benign solvents carbon dioxide and water, which are nontoxic, nonflammable and inexpensive, may be substi- tuted for toxic organic solvents in chemical processing. Applications include dry cleaning [3], photoresist drying [4], nanoparticle synthesis [5], enzymatic catalysis [6], and organometallic catalysis [7]. So far, several attempts have been applied to prepare semifluorinated block copolymers by means of cationic [8–10], anionic [11,12], living radical [13], and group transfer polymerisation (GTP) [14]. Solution properties of block copolymers are greatly influenced by the length and the ratio of block segments, so precise controlling of the chemical structure and the molecular weight is very important to manipulate the properties. Recently, we reported on the synthesis of poly (ethylene oxide) (PEO)-b-PFOMA copolymers by ATRP using a PEO macroinitiator [15]. The polymerisation yielded well-defined block copolymers with controlled molecular weight. It was demonstrated that the block copolymers formed micelles where PEO is the shell and PFOMA is the core in water and chloroform and the micelle formation depended on the block ratio in the copolymers. The copolymer surfactant lowered the interfacial tension of the water – CO 2 interface due to both hydrophilicity of PEO block and highly CO 2 -philic nature of PFOMA block allowing the formation of stable W/C emulsions. The present article describes the synthesis of PDMAEMA-b-PFOMA copolymers via GTP. GTP has been extensively utilized for the preparation of various types of block copolymers with controlled molecular weight and narrow molecular weight distribution. A series of block copolymers are prepared by varying the ratio of monomers to an initiator, and the micellar characteristics of the copolymers are investigated by quasi-elastic light scattering (QELS) and transmission electron microscopy (TEM). In addition, the solubility of copolymers in dense carbon 0032-3861/03/$ - see front matter q 2003 Elsevier Ltd. All rights reserved. doi:10.1016/S0032-3861(03)00566-4 Polymer 44 (2003) 5153–5158 www.elsevier.com/locate/polymer * Corresponding author. Tel.: þ 82-51-620-1692; fax: þ82-51-625-2229. E-mail address: ktlim@pknu.ac.kr (K.T. Lim).