Hierarchical Structure and Dynamics of a Polymer/Nanoparticle Hybrid Displaying Attractive Polymer–Particle Interaction

Abstract

X-ray photon correlation spectroscopy and small-angle Xray scattering were used to study the thermally driven motion and hierarchical structure of palladium (Pd) nanoparticles (NPs) in the concentrated solutions composed of polymers with different molecular weights. The Pd NPs were formed by in situ reduction of palladium(II) acetylacetonate (Pd(acac) 2 ) in the solution of poly(2-vinylpyridine) (P2VP) and benzyl alcohol which acted as the reduction agent and solvent. Below the entanglement molecular weight (M e ) of P2VP, a diffusion mode was found together with a fractal structure built up by the primary particles spanning over a broad range of length scales. Above M e , a subdiffusive motion was identified along with diffusive motion, and the hybrids formed a fractal structure built by the local clusters assembled by primary particles. The structural differences were attributed to different kinetic pathways of NP organization mediated by attractive interaction between P2VP and Pd NPs as well as the viscosity of the matrix phase, and both are dependent on the polymer molecular weight. The bimodal dynamics was ascribed to overlapping dynamic spectra associated with the diffusion of the fractal entity and the constrained subdiffusion of the collective motion of NP clusters within it.

Kinetics and Mechanism of In Situ Metallization of Bulk DNA Films

“…During UV irradiation, an increase in the scattering intensities over the q range of Å with little changes in intensity at lower q was observed. This is consistent with the formation of isolated spherical particles, where the significant change in scattering is within the region corresponding to the form factor for isolated spheres [ 24 – 26 ]. If significant aggregation or inter-particle interaction was observed, an increase in the low- q scattering intensity would be seen together with a peak-like distortion at the q position corresponding to the particle diameter [ 24 – 26 ].…”

“…This is consistent with the formation of isolated spherical particles, where the significant change in scattering is within the region corresponding to the form factor for isolated spheres [ 24 – 26 ]. If significant aggregation or inter-particle interaction was observed, an increase in the low- q scattering intensity would be seen together with a peak-like distortion at the q position corresponding to the particle diameter [ 24 – 26 ]. To both quantify the final particle size and further highlight that the scattering is indeed related to isolated particles, the measurement from 2910 seconds was fitted to Eq.…”

Transparent ultraviolet-shielding composite films made from dispersing pristine zinc oxide nanoparticles in low-density polyethylene

“…As the polymer cluster started to dissolve at 188 h, the NPs began to diffuse into the polymer, and the agglomerates started to diminish [44]. The dispersion of the agglomerated NPs in the polymer solution is determined by two factors, namely, the van der Waals forces holding the NPs together and the Brownian motion for the diffusion of the NPs to move toward the direction of lower particle concentration [47]. The diffusion coefficient, D, for spherical NPs can be calculated using the Stokes-Einstein equation [48]: where k denotes the Boltzmann constant; T, the temperature in Kelvin; μ, the viscosity of the polymer solution; and d, the particle diameter.…”

Scaling Perspective on Dynamics of Nanoparticles in Polymers: Length- and Time-Scale Dependent Nanoparticle–Polymer Coupling

“…The development of nanoparticle chemistry in recent years has enabled the synthesis of nanoparticles with well-controlled size, shape, and surface chemistry, yielding a library of nanoparticles available for investigating fundamental scientific problems and exploring nanoparticle-based applications. Nanoparticles commonly used in the studies of nanoparticle dynamics in a polymer matrix − include polyhedral oligomeric silsesquioxanes (POSS) nanoparticles with the diameter d on the order of 1 to 3 nm, ,, quantum dots (QDs) with 2 nm < d < 10 nm, , gold nanoparticles with 5 nm < d < 400 nm, ,,,,,,,,,,,, magnetic nanoparticles with 5 nm < d < 20 nm, ,…”