Thermo- and pH-Responsive Association Behavior of Dual Hydrophilic Graft Chitosan Terpolymer Synthesized via ATRP and Click Chemistry

A comb-like dual hydrophilic graft chitosan terpolymer, chitosan grafted with both poly[(2-dimethylamino)ethyl)ethyl methacrylate] and poly(N-isopropylacrylamide) or, simply, CS(-g-PDMAEMA)-g-PNI-PAM, was synthesized by means of atom transfer radical polymerization (A-FRI)) and click chemistry At first, PDMAEMA A and PNIPAM were synthesized via ATRP. followed by substituting the halide end groups with azido group After converting CS into alkynyl-CS via amidation. PDMAEMA-N-3 and PNIPAM-N-3 side chains were successfully grafted onto the CS backbone via click reaction, leading to the well-defined graft terpolymer Thermo- and pH-responsive micellization behavior of the Si aft terpolymer in aqueous solutions was investigated by proton nuclear magnetic resonance (H-1 NMR), laser light scattering (LLS), surface tensiometry, zeta potential, and transmission electron microscopy (TEM) The core-shell structured micelles with PNIAPM as a cote and CS/PDMAEMA as a shell were formed in acidic environment (pH < 4) at elevated temperature ( > 38 degrees C), whereas the time turned into the micelles with CS/PDMAEM A cores in alkaline solutions (pH > 7) at room temperature