Synthesis of Macroporous Poly(styrene-co-divinylbenzene) Microparticles Using n-Heptane as the Porogen:  Quantitative Effects of the DVB Concentration and the Monomeric Fraction on Their Structural Characteristics

Abstract

Macroporous poly(styrene-co-divinylbenzene) microparticles from reactive mixtures with various divinylbenzene and diluent contents have been synthesized. n-Heptane, which is a poor solvent for the copolymer, was used as diluent of the organic phase during the polymerization to obtain a high percentage of meso- and macropores, which are the most useful pores in the adsorption of macromolecules of medium and large sizes, such as proteins. The research was planned through a factorial design of experiments in an attempt to determine a quantitative relationship between the pore characteristics of the microparticles obtained and the concentration of the divinylbenzene and of the diluent used in the reactive mixture. The nitrogen adsorption−desorption isotherm and the curve of mercury intrusion for each type of microparticle were obtained, and the BET-specific surface areas and the volumes of macro-, meso-, and micropores were determined. Finally, empirical models correlating the synthesis conditions with the BET-specific surface area and the volumes of the micro-, meso-, and macropores were calculated; it was observed that the higher the divinylbenzene concentration in the monomeric mixture, the higher the volumes of micro- and mesopores and the larger the BET-specific surface area. It was also concluded that the higher the amount of diluent, the higher the volumes of meso- and macropores. Within the scope of the work, these models permit the synthesis of adsorbents with predetermined pore properties.

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…On the other hand, if a nonsolvent for the final polymer is used as a porogen, such as n-heptane [13] instead of toluene in the previous case, pore formation occurs via χ-induced syneresis [1]. In this case, phase separation occurs before the gelation point since heptane cannot swell/dissolve the growing polymer chains.…”

“…Mercury intrusion porosimetry curves can also be used. A slope instead of a plateau for the second zone of the curves indicates low mechanical strength [13,293]. In addition, combination of TGA and DSC is also proposed as a method of mechanical strength measurement [72][73].…”

A novel route for synthesis of cross-linked polystyrene copolymer beads with tunable porosity using guar and xanthan gums from bioresources as alternative synthetic suspension stabilizers

“…In the preparation of the polymer beads, the dispersion of the organic phase in the continuous phase is the determining step in establishing the particle size distribution of the final polymer beads. This is influenced by the geometrical factors of the reactor, operating parameters and substance parameters (type and concentration of stabilizers, viscosities of continuous and dispersed phases, interfacial tension) [31,32]. …”

Preparation and characterization of porous crosslinked microspheres of new aromatic methacrylates

“…The porous structure of microspheres formed in this way is generated by the use of pore-forming diluents. Appropriate selection of poreforming diluents allows obtaining microspheres with tailormade morphological properties [16,17]. Kun and Kunin [18,19] determined the influence of porogenic diluents on the porous structure of styrene-divinylbenzene copolymers indicating sol and nonsol diluents.…”