Domain-Size Effects in Optical Diffraction from Polymer/Composite Microparticles

Abstract

Poly(ethylene glycol) [PEG] microparticles were doped with ceramic or latex nanoparticles in order to examine domain-size and refractive index effects of nanometer-sized guest inclusions on two-dimensional diffraction patterns. Composite microparticles were examined for different inclusion sizes and polymer/nanoparticle weight ratios in order to determine the size and number-density threshold of detection for guest nanoparticles within the polymer host as indicated by fringe distortion in 2-D angular scattering. PEG host particles having a 10 μm (nominal) diameter were formed with three different guest nanoparticles (Al2O3, TiO2, and latex nanospheres with respective sizes of 46, 29, and 14 nm). For the ceramic nanoparticle inclusions, distortion was observed at relative guest−host weight fractions of 5−10%. For the 14 nm latex inclusions, no distortion was observed at any weight fraction. A perturbation method was used to simulate the effect of nanometer-size inclusions on 2-D optical diffraction from polymer host microparticles and to suggest how the distortions should vary with inclusion size, refractive index, and number.

Probing Phase-Separation Behavior in Polymer-Blend Microparticles: Effects of Particle Size and Polymer Mobility

“…Of particular interest is the minimum size of such domains to result in a measurable (quantifiable) distortion. Recently, we have investigated in detail effects of phase-separated domain size and number density both experimentally and theoretically using polymer/ceramic heterogeneous composite particles . These studies confirm sensitivity of this technique to material inhomogeneity on a length scale of about 30 nm.…”

“…Qualitatively, phase separation within the particle results in a nonuniform refractive index which manifests itself as vertical distortion (or complete absence) of diffraction fringes. Quantitatively, material inhomogeneity is manifested in poor agreement with Mie theory calculations as well as subtle differences (as compared with homogeneous particles) in Fourier transforms of vertical fringes . In our experimental configuration, far-field diffraction data were acquired using ( f /1.5) collimating optics and a thermoelectrically cooled CCD camera (SpectraSource Instruments) digitized at 16 bits .…”

A study on the fundamental ceramic–polymer interactions in the high CeO2-loading polyethylene glycol blend

“…With respect to the preparation of a polymer-ceramic blend for extrusion or molding purpose, there are several approaches: (1) introduction of the desired ceramic powder into a polymer solution (followed by removing the solvent) [37][38][39][40][41][42] or into a polymer melt; 43 (2) use of organometallic polymers as pre-ceramic matrix; [44][45][46][47][48][49] and (3) perpetrating polymerization at the surface of ceramic fine particles. [50][51][52][53] Of these methods, direct solution mixing is obviously a simple and practical way to the preparation of extrusion feedstock.…”

Vibrational Normal Modes of Polymer Nanoparticle Dimers Using the Time-Averaged Normal Coordinate Analysis Method

“…There has been a great deal of interest in recent years on the production, analysis, and properties of monodisperse polymer particles, following experimental techniques that have allowed for uniform production of polymer particles of arbitrary size and construction. Much work has gone into experimental analysis − and theoretical study − of these particles and their properties.…”

“…Frequently, large molecular systems, such as proteins, are observed in the presence of solvent, the motions of which are strongly coupled to the conformational motion of the molecule. In the present case under investigation, we simulate polymer spheres in the absence of solvent, under conditions similar to those under which they are experimentally observed. − …”