Pore structure of macroporous monolithic cryogels prepared from poly(vinyl alcohol)

Macroporous monolithic cryogels made from poly(vinyl alcohol) (PVA) with degree of saponification 87.7% have been prepared using a crosslinking reaction with glutaraldehyde under acidic conditions at subzero temperatures. The porous structure of the monolithic cryogels from PVA (cryoPVA), analyzed using optical microscopy, scanning electron microscopy, and environmental scanning electron microscopy, revealed interconnected macropores up to 150 m in size with a noticeable microporosity of the gel walls. Differential scanning calorimetry measurement showed that more than 90% of the water in the cryoPVA monoliths was freezable water, while the amount of polymer bound water increased with increase in the polymer concentration in the cryoPVA sample. The swelling degree of cryoPVA depended on concentration of polymer in the initial reaction mixture and degree of crosslinking. The cryoPVA monoliths were elastic and spongy-like materials that can be dried, stored in dried state, and re-swelled when required. Derivatization of hydroxyl-groups of the cryoPVA monolith allowed incorporation of required functionality. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1057-1066, 2006