Preparation of hydrophobically modified associating multiblock copolymers via a one-pot aqueous RAFT polymerization

We describe an efficient strategy for the preparation of hydrophobically associating multiblock copolymers using the RAFT technique. Polymerization reactions were carried out in a one-pot aqueous RAFT polymerization at 70 oC using a symmetrical trithiocarbonate as chain transfer agent (CTA) in aqueous media. The macroRAFT polyacrylamide (PAM) was synthetized and chain extended by polymerization of N,N'-dihexylacrylamide (DHAM) and acrylamide (AM), respectively. The resultant polymers were intensely characterized by size exclusion chromatography (SEC), nuclear magnetic resonance (NMR), diffusion-ordered spectroscopy (DOSY), Fourier transformation- infrared (FT-IR) and Rheology. The structure and insertion of hydrophobic block (PDHAM) into backbone were carefully demonstrated. The rheological measurements confirmed the effect of the hydrophobic block number on the viscosity of polymers at different concentration and the formation of reversible physical network of entangled polymers in aqueous media. Moreover, the incorporation of hydrophobic block (PDHAM) was established by the oscillatory measurement.