Macromolecules, Vol.35, No.1, 97-105, 2002
Preparation and porosity characterization of highly cross-linked polymer resins derived from multifunctional (meth)acrylate monomers
Permanently porous polymer resins derived from multifunctional (meth)acrylate monomers have been prepared by suspension polymerization. The dry state porosity characteristics have been evaluated using N-2 sorption and Hg intrusion porosimetry, and the results correlated in terms of the three-dimensional cohesion parameter, delta (t), of the polymers and porogens. The pore size distributions of almost all resins cover a broad range from micro- through meso- to macropores. The porosity data had to be computed from the adsorption branches of the N-2 sorption isotherms, since an artifact arises in the pore size distributions if derived from the corresponding desorption data. The artifact is attributed to a percolation process in the desorption mechanism. The correlation of porosity data (e.g., the Brunauer, Emmett, and Teller (BET) surface area and the Barret, Joyner, and Halenda (BJH) average pore radius) with the nature of the porogen was found to be very limited if the one-dimensional Hildebrand solubility parameter, delta, only is used. However, by application of a group contribution method due to Hoftyzer-Van Krevelen and Hoy, three-dimensional cohesion parameters, delta (t), and the porogen-polymer affinity parameters, d(0), could be calculated. Using the latter as the basis for a new correlation the N-2 sorption BET computed surface areas of resins show an inverse proportional relationship with d(0), while BJH average pore radii show a proportional relationship.