Solvent-Mediated Isolation of Polymer-Grafted Nanoparticles

Abstract

Nanoparticles (NPs) functionalized with polymers have a broad range of applications; however, a key challenge is to achieve high-yield and time-efficient isolation of the polymer-capped NPs from free polymers. Here, we introduce a highly effective thermodynamically driven approach to isolate polymer-grafted NPs. By controllably reducing the solvent quality for the polymer tethers, cellulose nanocrystals end-grafted with poly(N-isopropyl acrylamide) (pNIPAm) were isolated from free pNIPAm. More specifically, under poor solvency conditions, polymer-tethered NPs aggregated and precipitated, while the free polymer remained in the supernatant. The method was validated for the NPs end-grafted with pNIPAm with different molecular weights. The approach was theoretically rationalized using a scaling approach. Based on the NP isolation time and separation efficiency, the solvent-mediated method favorably compared with conventional dialysis and membrane filtration separation techniques and thus can be used for a variety of polymer-functionalized NPs.

From Nature‐Sourced Polysaccharide Particles to Advanced Functional Materials

“…[157] This approach enables straightforward characterization of the grafted polymer, e.g., molecular weight, [158] and the utilization of commercially available polymers. [159] The most extensively used reactions for coupling polymers with PSPs involve amide bond formation by EDC/NHS coupling, [159] azide-alkyne click-reactions, [160] and ether bond formation. [157] In the "grafting from" approach, functional groups of the PSP surface are used to initiate polymerization via atom transfer radical polymerization (ATRP), [152] reversible additionfragmentation chain transfer (RAFT) polymerization, [160] or nitroxide-mediated polymerization (NMP).…”

“…[159] The most extensively used reactions for coupling polymers with PSPs involve amide bond formation by EDC/NHS coupling, [159] azide-alkyne click-reactions, [160] and ether bond formation. [157] In the "grafting from" approach, functional groups of the PSP surface are used to initiate polymerization via atom transfer radical polymerization (ATRP), [152] reversible additionfragmentation chain transfer (RAFT) polymerization, [160] or nitroxide-mediated polymerization (NMP). [161] The "grafting from" methods can provide a high polymer grafting density on the PSP surface and can be used when the polymer is insol-uble in the solvent of the PSP dispersion.…”

“…[ 157 ] This approach enables straightforward characterization of the grafted polymer, e.g., molecular weight, [ 158 ] and the utilization of commercially available polymers. [ 159 ] The most extensively used reactions for coupling polymers with PSPs involve amide bond formation by EDC/NHS coupling, [ 159 ] azide–alkyne click‐reactions, [ 160 ] and ether bond formation. [ 157 ]…”