No abstract

Nitroxide‐mediated polymerization (NMP) is employed to graft synthetic polymers from polysaccharides. This work demonstrates the first successful polymer grafting from starch nanoparticles (SNPs) via NMP. To graft synthetic polymers from the SNPs' surface, the SNPs are first functionalized with 4‐vinylbenzyl chloride prior to reaction with BlocBuilder MA yielding a macroinitiator. Methyl methacrylate with styrene, acrylic acid, or methyl acrylate are then grafted from the SNPs. The polymerizations exhibited linear reaction kinetics, indicating that they are well controlled. Thermal gravimetric analysis and spectroscopic techniques confirmed the synthesis of the precursors materials and the success of the grafting from polymerizations. The incorporation of hydrophobic synthetic polymers on hydrophilic SNPs yields new hybrid materials that could find use in several industrial applications including paper coatings, adhesives, and paints.

Starch nanoparticles (SNP) were modified with styrene oxide (STO) and successfully used as Pickering stabilizers in miniemulsion and emulsion polymerization.

Starch nanoparticles (SNP) were modified with synthetic polymers using the "grafting to" approach and nitroxidemediated polymerization. SG1-capped poly(methyl methacrylate-costyrene) (P(MMA-co-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-g-P(MMA-co-S), were characterized by 1 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 −1 ) 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.

The grafting to approach and nitroxide‐mediated polymerization (NMP) were used to graft modify starch nanoparticles (SNP) with pH‐responsive polymers. SG1‐capped poly(2‐(dimethylamino)ethyl methacrylate‐co‐styrene), P(DMAEMA‐co‐S), and poly(2‐(diethylamino)ethyl methacrylate‐co‐styrene), P(DEAEMA‐co‐S), with relatively low dispersity and high degree of livingness was synthesized in bulk via NMP using a commercial available alkoxyamine. These macroalkoxyamines were then grafted to vinyl benzyl‐functionalized SNP (SNP‐VBC) to obtain pH‐responsive materials. The grafted SNP were characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis confirming the successful synthesis of these new materials. Low grafting efficiencies (~6%) were observed for both SNP‐grafted materials with pH‐responsive polymers, as expected when using the grafting to approach. The pH‐responsiveness of SNP‐g‐P(DMAEMA‐co‐S) and SNP‐g‐P(DEAEMA‐co‐S) was confirmed by measuring the ζ‐potential at different pH values. At acidic conditions (pH 3–6) the grafted materials were protonated and exhibited positive ζ‐potential, whereas at basic conditions (pH 10–13) the same grafted materials were deprotonated and exhibited negative ζ‐potential.