Control of Porous Morphology in Suspension Polymerized Poly(divinylbenzene) Resins Using Oligomeric Porogens

• Published in: Macromolecules 2004-10, Vol.37 (20), p.7628-7636
• Main Authors: Macintyre, Fiona S, Sherrington, David C
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma0491053

Porous poly(divinylbenzene) (DVB) resins have been prepared using suspension polymerization with toluene and an oligomer as coporogens. The oligomers investigated were poly(propylene glycol) 1000 (PPG 1000), poly(propylene glycol) 4000 (PPG 4000), and poly(dimethylsiloxane) (PDMS). The porogen was used in a 1/1 vol/vol ratio with DVB, and with each oligomeric coporogen the full compositional range 100 vol % toluene to 100 vol % oligomer was examined. As predicted from previous knowledge of the effect of different solvent porogens, toluene yielded a highly microporous resin with a large dry state surface area (∼650 m2 g-1), whereas each oligomeric porogen yielded a highly macroporous resin with rather low surface area ∼15−50 m2 g-1. Using mixtures of toluene and oligomer as coporogens, we speculated that it might be possible to produce a resin with a strongly bimodal pore size distribution with one population of pores in the micropore region, and one in the macropore region. This proved to be the case with a mixture 80 vol % toluene and 20 vol % PDMS. Unexpectedly, however, the surface area of the poly(DVB) resins was found to rise significantly (∼100 m2 g-1) in shifting from toluene as sole porogen to a mixture with a low level of oligomeric coporogen (∼4−6 vol %). Further increase in the level of oligomer led to the predicted fall in surface area. Overall, therefore, it is clear that use of oligomers, particularly as coporogens with solvent porogens, provides a valuable methodology for fine-tuning the porous morphology of poly(DVB) resins.