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oai:figshare.com:article/34021121 2026-09-29T04:14:02Z category_1 category_915 category_7 category_21 category_873 category_132 portal_63 item_type_6 month_year_09_2026

A Nondestructive Method to Quantify Polymer Graft Density on Nanoparticles Using Optical Extinction Spectra Masoud Abdi (13798000) Irene Andreu (1650748) Ryan Poling-Skutvik (1506904) Biophysics Physical Sciences not elsewhere classified Medicine Biotechnology Chemical Sciences not elsewhere classified Infectious Diseases obtain radial profiles differential spherical shells cylindrical segments passing bypassing challenges provided nondestructive optical approach grafting densities obtained existing characterization approaches polymer volume fraction polymer molecular weight require prior knowledge refractive index across effective refractive index grafted polymer changing grafted polymer chains grafted nanoparticle matches prior knowledge grafted nanoparticles nondestructive method local refractive index sensitivity index profile grafting density existing methods calculated refractive polymer corona specific applications plasmonic near nanoparticle sizes iteratively adjusting gold core finally determined field decay complex instrumentation chemical properties advantages provide >< sub Grafting density is the key parameter governing colloidal stability and structure for polymer-grafted nanoparticles (PGNPs). Existing methods to quantify grafting density either destroy the sample, require prior knowledge of polymer molecular weight <i>M</i>_n, or rely on complex instrumentation. Here, we present a nondestructive optical approach that determines grafting density directly from shifts in the localized surface plasmon resonance peak caused by the grafted polymer changing the local effective refractive index. To interpret this shift, the grafted polymer chains are approximated as cylindrical segments passing through differential spherical shells to obtain radial profiles for the polymer volume fraction and refractive index across the polymer corona. The local refractive-index profile is weighted by the plasmonic near-field decay to calculate the effective refractive index sensed by the nanoparticle. The grafting density is finally determined by iteratively adjusting the effective refractive index until the calculated refractive-index sensitivity of the polymer-grafted nanoparticle matches that of the gold core. The grafting densities obtained from this optical method quantitatively agree with established experimental benchmarks across different polymer <i>M</i>_n, grafting densities, nanoparticle sizes, and solvents. Our approach uses common laboratory equipment, eliminates the need for prior knowledge of polymer <i>M</i>_n, and preserves the sample for further experiments, bypassing challenges provided by existing characterization approaches. Together, these advantages provide a framework for predicting and understanding the physical and chemical properties of PGNPs for specific applications. 2026-09-29T00:00:00Z Text Journal contribution 10.1021/acsnano.6c11390.s001 https://figshare.com/articles/journal_contribution/A_Nondestructive_Method_to_Quantify_Polymer_Graft_Density_on_Nanoparticles_Using_Optical_Extinction_Spectra/34021121 CC BY-NC 4.0