1 e-Polymers 2009, no. 035 http://www.e-polymers.org ISSN 1618-7229 (Quaternized/betainized) amino-based amphiphilic block copolymers: quantitative composition characterization via FTIR and thermogravimetry João A. S. Bomfim, Rosica Mincheva, Alexandre Beigbeder, Olivier Persenaire and Philippe Dubois * Laboratory of Polymeric and Composite Materials, Center of Innovation and Research in Materials and Polymers (CIRMAP), Materia Nova Research Center, University of Mons Hainaut, 20 Place du Parc, B-7000 Mons, Belgium; fax: +32- (0)65-373484; e-mail: philippe.dubois@umh.ac.be (Received: 22 September, 2008; published 06 April, 2009) Abstract: The objective of the present study is the introduction of well known and readily accessible analytical methods as FTIR, thermogravimetric (TGA) and evolved gas analysis (EGA) for quantitative determination of the degree of polymerization (DP) and degree of quaternization (DQ)/betainization (DB) of amino-based amphiphilic block copolymers. For this purpose a series of amphiphilic poly(dimethylsiloxane)-b-poly[2-{dimethylamino)ethyl methacrylate] (PDMS-b-DMAEMA) diblock copolymers with DP of the PDMAEMA-block ranging from 22 to 162 was synthesized by atom transfer radical polymerization and analyzed by 1 H NMR, ATR-FTIR and TGA-co-EGA. The determined composition results have shown linear correlation between the FTIR or TGA and the 1 H NMR data and equations allowing the quantitative calculation of PDMAEMA-block DP were found. The errors estimated by ATR-FTIR were less than 1.5%. Further, the PDMAEMA-block was quaternized (or betainized) with DQ (or DB) from 25 % to 100 % and analyzed by TGA-co-EGA. Again, a linear correlation between the quaternized (betainized) PDMAEMA-block mass fraction and the DQ (DB) degrees was obtained by 1 H NMR. Introduction Amphiphilic block copolymers are present in a wide number of applications, such as surfactants, emulsifiers, compatibilizers, etc. Such versatility arises from the different types of supramolecular arrangements (micelles, vesicles, etc.) that can be formed in water or non-aqueous dispersive media for which each block presents different Flory- Huggins interaction parameter [1, 2, 3]. Among the polymer blocks used, the polyelectrolyte-based and especially poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) revealed to be particularly attractive. Actually, PDMAEMA, due to its pK a close to neutrality [4]) can be readily solubilized in aqueous medium through protonation of tertiary amine pending groups. Consequently, PDMAEMA-based homo- and copolymers and their quaternized derivatives like poly[2- (methacryloylethyl)trimethylammonium] iodide (PMAETMA-I) have been widely studied for a number of applications such as membranes for gas separations [5], polyelectrolyte complexes [6], DNA-binding agents for non-viral gene delivery systems [7] or non-leaching antifouling surfaces [8, 9]. Recently, PDMAEMA-based (co)polymers, containing both positive and negative charges on each monomer unit