Permeation of polyelectrolytes and other solutes into the pore spaces of water-swollen cellulose: A review

Abstract

The rate and extent of transport of macromolecules and other solutes into cellulosic materials and fibers have important applications in such fields as papermaking, textiles, medicine, and chromatography. This review considers how diffusion and flow affect permeation into wood, paper, and other lignocellulosic materials. Because pore sizes within such materials can range from nanometers to millimeters, a broad perspective will be used, also considering some publications related to other porous materials. Factors that limit the rate or extent of polymer or other solute transport into pores can involve thermodynamics (affecting the driving motivation for permeation), kinetics (if there is insufficient time for the system to come to equilibrium), and physical barriers. Molecular flow is also affected by the attributes of the solute, such as molecular mass and charge, as well as those of the substrate, such as the pore size, interconnectedness, restricted areas, and surface characteristics. Published articles have helped to clarify which of these factors may have a controlling influence on molecular transport in different situations.

Plant Nanomaterials and Inspiration from Nature: Water Interactions and Hierarchically Structured Hydrogels

“…For micropores (radius <2 nm) and small mesopores (2 nm < radius < 10 nm) other considerations come into play due to extremely low Reynolds numbers and, thus, highly viscous flows. [ 68 ] Furthermore, in such circumstances the presence of macromolecules such as proteins or polyelectrolytes, [ 69 ] e.g., in complex fluids, changes the liquid–substrate interface, consequently affecting the dynamics of the process and the total capillary pressure. For cellulosic substrates, wetting and liquid viscosity promote wicking of a cellulose sponge with water and turpentine oil.…”

Accessibility of fiber surface sites for polymeric additives determines dry and wet tensile strength of paper sheets

“…The pore sizes of the paper sheets used in our study range from tens of nanometers to 30 lm and was analyzed by mercury-intrusion (for an example of the latter see supporting information). With respect to the adsorption of macromolecules on/in paper fibers, smaller pores in the cell walls were studied by various methods and values ranging from 10 to 100 nm were reported (Wu et al 2009). Pores and grooves that are on the order of the size of an unperturbed polymer chain may not be trivial to be accessed by the macromolecules due to confinement effects (i.e.…”

Implications of apparent pseudo-second-order adsorption kinetics onto cellulosic materials: A review

“…Since small molecules and ions tend to diffuse rapidly in solution, they would be able to adopt essentially all of their possible molecular conformations within tiny pore spaces in fractions of seconds, including high numbers of collisions with, and possible detachments from, an adjacent solid surface. Relatively long times for a molecule to collide with and adsorb onto a surface, excluding times required for diffusion, have been documented only for quite large molecules, such as high-mass polyelectrolytes (Ödberg et al 1993;Alince 2002;Wu et al 2009b).…”

“…In particular, it is reasonable to expect that enzymes such as cellulase can remain attached to a cellulose surface while remaining in motion (Jervis et al 1997;Zhang et al 2016), though such motion may become constrained (Moran-Mirabal et al 2013). Such systems have been discussed by Wu et al (2009b). The surface diffusion mechanism can be expected to have relevance in cellulose-based systems due to the orientation of such structures as the fiber surfaces, lumen spaces, the local alignment of fibrils, and the slit-like shape of pores within cellulosic fibers after chemical pulping has removed most of the lignin.…”