Do Very Small POSS Nanoparticles Perturb s-PMMA Chain Conformations?

Published

July 21, 2018

Author(s)

Nicolas Jouault, Sanat K. Kumar, Robert J. Smalley, Changzai Chi, Robert Moneta, Barbara Wood, Holly Salerno, Yuri B. Melnichenko, Lilin He, William E. Guise, Boualem Hammouda, Michael K. Crawford

Abstract

Small-Angle Neutron Scattering (SANS) measurements of polymers mixed with weakly attractive 1.0 nm diameter polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs) show no observable changes in the chain radius of gyration R_g, regardless of the molecular weight of the PMMA chains, the amount of residual solvent, or the POSS NP loading (from 0 to 20%v/v). The SANS results are augmented by small and wide-angle X0ray scattering (SAXS and WAXS), transmission electron microscopy (TEM), and Raman spectroscopy measurements used to characterize the NP dispersion and the amount of residual solvent in the nanocomposites (PNCs) under different annealing conditions. In retrospect, these results are not surprising since scaling arguments imply that chain size in the concentrated region of the phase diagram of a polymer solution is independent of the volume fraction of plymer, and only as the semi-dilute region is entered with decreasing concentration does the chain size for a good solvent scales with polymer volume fraction as Φ^1/8_polymer. Thus at POSS loadings > 50 % v/v, well within the concentrated region, no changes of polymer size are expected. By combining these results with our previous results and those of many others we conclude that NPs apparently have little effect on the conformations of polymer chains, especially in typical PNCs that only incorporate moderate amounts of filler.

Citation

Macromolecules

Volume

51

Issue

14

Pub Type

Journals

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Keywords

nanoparticles, SANS, SAXS, polymer/nanoparticles, radius of gyration

Citation

Jouault, N. , Kumar, S. , Smalley, R. , Chi, C. , Moneta, R. , Wood, B. , Salerno, H. , Melnichenko, Y. , He, L. , Guise, W. , Hammouda, B. and Crawford, M. (2018), Do Very Small POSS Nanoparticles Perturb s-PMMA Chain Conformations?, Macromolecules, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=925049 (Accessed September 12, 2024)