One-Pot Synthesis of Thermoresponsive Cellulose-Based Miktoarm Graft Copolymer by Simultaneous ATRP and ROP

In this work, we report a one-pot synthesis of amphiphilic miktoarm cellulose graft copolymers, cellulose (-graft-oligo(L-lactide))-graft-oligo(N-isopropylacrylamide) (Cell(-g-OLLA)-g-ONIPAM), with dual side chains of oligo(L-lactide) and oligo(N-isopropylacrylamide) using 2-bromoisobutyl bromide functionalized cellulose (Cell(-OH)-Br) as the macroinitiator, by simultaneously conducting ring-opening polymerization and atom transfer radical polymerization using Cu/CuBr/PMDETA/Sn(Oct)2 as the catalytic system. The chemical structures and thermal properties of Cell(-g-OLLA)-g-ONIPAMs were characterized with 1H and 13C nuclear magnetic resonance spectroscopy, differential scanning calorimetry and thermal gravimetric analysis. Cell (-g-OLLA)-g-ONIPAM could self-assemble into micelles in the aqueous solution as confirmed by environmental scanning electron microscopy and dynamic light scattering analyses. The micellar aggregates showed a temperature-responsive property and the sizes of micelles were influenced by the ratio of temperature-responsive ONIPAM side chains. The miktoarm graft copolymers have potential applications as biomedical or intelligent materials.