Control of the Porous Structure of Polystyrene Particles Obtained by Nonsolvent Induced Phase Separation

Abstract

Porous polystyrene microspheres were produced by a process of nonsolvent induced phase separation (NIPS) from ternary polymer-solvent-nonsolvent (polystyrene-toluene-ethanol) systems and characterized by scanning electron microscopy (SEM) and small-angle X-ray scattering (SAXS) techniques. This study provides evidence for a link between the structural morphology of the porous polystyrene particles and the polystyrene concentration in the initial solutions. A reciprocal relationship between pore diameter and polymer concentration was observed for the systems with the polymer amount below the critical chain overlap concentration, C*. Above C*, this relationship breaks down. The reciprocal relationship between porosity and polymer concentration can be used to facilitate the fine control of the void size. We demonstrate that the observed reciprocal relationship between pore diameter and polymer concentration correlates well with the relative amount of nonsolvent present in the system at the onset of the phase separation process. The pore size can be reduced and, consequently, the pore surface area can be increased either by reducing the polymer concentration in the initial solution or by decreasing the polymer molecular weight in the sample composition.

Evaluation of the Chemical, Morphological and Dielectric Properties of Supramolecular Networks Consisting of Polyethylene Glycol Polyrotaxanes and Polystyrene/Semi‐Rotaxane with Hydroxypropyl‐β‐Cyclodextrins

“…To estimate the average pore size of the samples, image J analysis software was used. [ 33 ] It should be noted that to obtain accurate data, a statistical correction was introduced as it was very likely that the measured pores diameters, d , to be smaller than the true diameter, D . This statistical correction assumed that the pores are spherical and the equatorial diameter, D , of a spherical void is related to the diameter d measured from SEM image, by a parameter h .…”

Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation

“…Similar conclusions have been drawn for observed the porosity of non-solvent induced precipitation of poly(styrene) particles. 61 At sufficiently low initial concentrations, however, this trend no longer applies, and only a thin polymer skin is formed, as discussed below. Overall, these results combined enable the predictive design of microporous PVA particles with controlled dimensions (R N ) and timescales (t), across various concentrations of a given M w polymer.…”

Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

“…Phase inversion method, subcritical CO 2 foaming, freezedrying, gas foaming, micro-molding and 3D printing have been widely used to prepare EMI shielding materials with porous structures [24][25][26]. Phase separation methods include non-solvent-induced phase separation (NIPS), thermally induced phase separation (TIPS) and vapor-induced phase separation (VIPS) [27,28].…”