Conformation of Arborescent Polymers in Solution by Small-Angle Neutron Scattering: Segment Density and Core-Shell Morphology

Published

October 12, 2021

Author(s)

Seok I. Yun, Kai-Chi Lai, R M. Briber, Steven Teertstra, M Gauthier, Barry J. Bauer

Abstract

The radius of gyration (Rg) was determined as a function of generation number for arborescent polystyrenes with two different side chain molecular weights (Mw = 5000, 5K versus 30000, 30K) by small-angle neutron scattering (SANS) measurements. The Rg values obtained were analyzed in terms of the Zimm-Stockmayer model for randomly branched polymers, the scaling relationship (Rg = Mwv), and the expansion factor ( ). The Rg and scaling exponent (v = 0.26 ? 0.01) for G0 through G3 polymers with 5K side chains in cyclohexane-d corresponded to the values predicted by the Zimm-Stockmayer model. The Rg for G1 through G3 polymers with 30K side chains deviated from the model with v = 0.35 ? 0.04, closer to the value v = 0.33 expected for spheres of uniform density.Deuterated polystyrene (PS-d) side chains were grafted onto G2 and G3 polystyrene (PS) cores. These copolymers of G2PS-graft-PS-d and G3PS-graft-PS-d were characterized as spheres with a well defined PS core - PS-d shell structure by the SANS contrast matching method. The shape and the segment radial density profile of the core and shell for GPS-graft-PS-d were determined based on P(r) and ??(r) obtained by indirect Fourier transformation and deconvolution methods (P(r): pair distance distribution function P(r) and ??(r) = ?(r) - ?(solvent): scattering length density contrast profile).

Citation

Macromolecules

Pub Type

Journals

Keywords

arborescent, dendrimer, graft, polystyrene, SANS, scaling, segment density

Citation

Yun, S. , Lai, K. , Briber, R. , Teertstra, S. , Gauthier, M. and Bauer, B. (2021), Conformation of Arborescent Polymers in Solution by Small-Angle Neutron Scattering: Segment Density and Core-Shell Morphology, Macromolecules (Accessed October 9, 2024)