Rigid Macroporous Polynorbornene Monoliths by Ring Opening Metathesis Polymerization
Abstract
Rigid macroporous polymer monoliths are widely used as efficient stationary phases for chromatographic separations, flow-through reactors, catalyst supports etc. An efficient sol-gel bottom-up synthetic approach involves polymerization of soluble monomers into an insoluble polymer that phase-separates into colloidal particles that under the right conditions of molecular structure, concentration, solvent and temperature form gels. Early phase-separation, hence smaller colloidal particles, can be induced by molecular-level cross-linking in the growing polymer akin to that in thermoset resins. Alternatively, for highly soluble linear (thermoplastic) polymers, phase-separation can be controlled with non-solvents. This is demonstrated here with open-cell macroporous polynorbornene monoliths synthesized by ring opening metathesis polymerization (ROMP) of norbornene in toluene using isopropanol (iPrOH) as non-solvent. Wet-gels were solvent-exchanged with liquid CO2 taken out at the end as a supercritical fluid (SCF). Changes in the microstructure as a function of the iPrOH:toluene ratio was probed by SEM, N2 sorption porosimetry. Bulk densities range from 0.40 to 0.68 g cm-3. Porosity ranges from 30 to 60% v/v with average pore diameters in the 1.4-2.3 mm range, but the BET surface area is low (1-3 m2 g-1. The skeletal framework consists of agglomerated particles forming macroglobular structures (1.8 to 4.5 µm in diameter). The monoliths are robust with e.g., ultimate compressive strength under high strain rates (1224 s-1) of samples made with iPrOH:toluene = 7:3 v/v (0.51 g cm-3) equal to 50 MPa at 75% ultimate strain.
Recommended Citation
D. Mohite et al., "Rigid Macroporous Polynorbornene Monoliths by Ring Opening Metathesis Polymerization," Abstracts of Papers of the American Chemical Society, American Chemical Society (ACS), Mar 2012.
Department(s)
Chemistry
Document Type
Article - Conference proceedings
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2012 American Chemical Society (ACS), All rights reserved.
Publication Date
01 Mar 2012
