Graft Modification of Starch Nanoparticles Using Nitroxide-Mediated Polymerization and the "Grafting to" Approach.

Starch nanoparticles (SNP) were modified with synthetic polymers using the "grafting to" approach and nitroxide-mediated polymerization. SG1-capped poly(methyl methacrylate--styrene) (P(MMA--S)) copolymers with low dispersity and high degree of livingness were first synthesized in bulk. These macroalkoxyamines were then grafted to vinyl benzyl-functionalized SNP to obtain biosynthetic hybrids. The grafted materials, SNP--P(MMA--S), were characterized by H NMR, FTIR, TGA, and elemental analysis. The total amount of grafted polymer and the grafting efficiency were evaluated for different molecular weights (5870-12150 g·mol) of the grafted polymer, the polymer addition approach (batch or semibatch) and the initial polymer loading (2.5, 5, or 10 g polymer/g SNP). The proposed approach presented in this work to graft modify SNP allows for a precise surface modification of the nanoparticles, while permitting that the final properties of the resulting biohybrid to be tunable according to the choice of polymer grafted.