Preparation of amphiphilic block copolymer containing triazene moieties and fluorescence study

Abstract

The present study describes the synthesis via microwave accelerated reversible additionfragmentation chain transfer (RAFT) polymerization of an amphiphilic block copolymer poly(acrylic acid)b-poly(dodecylacrylamide-co-1-(phenyl)-3-(2-methacryloyloxyethyl carbamoyloxyethyl)-3-methyltriazene-1) [PAA-b-(PDA-co-PUMA-T)]. The structure and the chemical composition of the block copolymer were confirmed by spectral/thermal analysis. The photoreactivity of the triazene sequences from PAA-b-(PDA-co-PUMA-T) was quantified by UV/vis irradiation in chloroform/dimethylformamide solutions and in thin film, indicating that the solvent polarity modifies with an order of magnitude the rate constant values. The lower rate constant in film state (k film = 1.3 × 10 −3 s −1 ), shows that the higher mobility of polymeric chains in solution allow a more rapid orientation, favourable to the triazene bond cleavage. The capability of block copolymer to form micelles in aqueous environment and implicitly, its critical micelle concentration (CMC) was evidenced through fluorescence measurements using pyrene probe (10 −6 M), the CMC value being of 4.64 × 10 −3 g L −1 PAA-b-(PDA-co-PUMA-T) (3.27 × 10 −7 M). Experiments of fluorescence quenching with various metal cations (UO 2+ 2 , Fe 2+ , Fe 3+ , Ni 2+ , Cu 2+ , Co 2+ , Pb 2+ and Hg 2+ ) suggested that such a block copolymer could find applications as fluorescence-based chemosensor for the detection of iron cations in homogeneous organic solutions or aqueous environments by thin films.

Nature of the adhesion bond between epoxy adhesive and titanium

“…The 3.67 eV laser radiation falls in the absorption band region of the aromatic ring [15] and excites the π* π transition in it [15,16]. The radiation in the reverse transition is detected in the range 1.5-3.7 eV (Fig.…”

Synthesis and characterization of comb-type graft copolymers by redox polymerization and "click" chemistry method

“…Copolymers have important interest for their mechanical properties and practical applications [9]. Block or graft copolymers are used in scientific applications and research [23][24][25][26][27][28][29][30][31]. One of the most important of these regularly branched polymers is the brush type copolymers.…”