Surface Structuring and Water Interactions of Nanocellulose Filaments Modified with Organosilanes toward Wearable Materials

Abstract

Colloidal dispersions of cellulose nanofibrils (CNFs) are viable alternatives to cellulose II dissolutions used for filament spinning. The porosity and water vapor affinity of CNF filaments make them suitable for controlled breathability. However, many textile applications also require water repellence. Here, we investigated the effects of postmodification of wet-spun CNF filaments via chemical vapor deposition (CVD). Two organosilanes with different numbers of methyl substituents were considered. Various surface structures were achieved, either as continuous, homogeneous coating layers or as three-dimensional, hairy-like assemblies. Such surface features reduced the surface energy, which significantly affected the interactions with water. Filaments with water contact angles of up to 116° were obtained, and surface energy measurements indicated the possibility of developing amphiphobicity. Dynamic vapor sorption and full immersion experiments were carried out to inquire about the interactions with water, whether in the liquid or gas forms. Mechanical tests revealed that the wet strength of the modified filaments were almost 3 times higher than that of the unmodified precursors. The hydrolytic and mechanical stabilities of the adsorbed layers were also revealed. Overall, our results shed light on the transformation of aqueous dispersions of CNFs into filaments that are suited for controlled interactions with water via concurrent hydrolysis and condensation reactions in CVD, while maintaining the moisture buffering capacity and breathability of related structures.

Mesoporous Carbon Microfibers for Electroactive Materials Derived from Lignocellulose Nanofibrils

“…Lignin from softwood contains high amounts of G units. In hardwood, similar amount of G and S units exist, whereas in grasses H is the main unit (Clark and Deswarte 2008). So far, the exact native lignin structure remains unknown since it is degraded and altered during extraction.…”

Ice-Templated Cellulose Nanofiber Filaments as a Reinforcement Material in Epoxy Composites

“…However, the filling process is typically time-consuming, and often an organic solvent has to be used to facilitate the impregnation. Another means of controlling the organization of the nanocellulosic entities is the formation of single filaments similar to those traditionally used in the textile industry [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. Dry spinning, wet spinning, and hydrodynamic alignment are some variations of the same approach and have all been successfully utilized in nanocellulose processing.…”

“…The filaments obtained via the spinning process are commonly in the micrometer scale. Considering the application of such materials in composites, the reported average diameters ranging 6.8–250 µm [ 11 , 12 , 13 , 14 , 15 , 16 , 17 ] suggest that the full potential of having a nanoscale raw material has not yet been reached. A better reinforcement effect could be expected by finding ways to decrease the lateral dimension of the filaments.…”

“…However, the commonly used solution-based silylation is not easily applicable to dried nanocellulose materials, because they tend to deform during the evaporation of the water-containing solvent. Chemical vapor deposition (CVD) is a more straightforward and efficient way to functionalize and hydrophobize cellulosic nanomaterials, such as cellulose nanofiber aerogels [ 23 ] and filaments [ 16 ]. In its simplest manifestation, the process consists of placing the cellulosic material and the liquid silane inside a closed container and vaporizing the chemical by heat and/or vacuum to cover the cellulosic surfaces.…”

Microfibers synthesized by wet-spinning of chitin nanomaterials: mechanical, structural and cell proliferation properties

“…Aer adjusting the spinning conditions, super-strong CNF bers have been manufactured, 7 which compete with the properties of known natural or synthetic biopolymeric materials. Moreover, owing to their abundant surface hydroxyl groups, functional bers (e.g., magnetic, 8 superabsorbents, 9 water-resistant, 10 specic polymer sorption 11 ) they can be obtained by optimizing the spinning dope, coagulant, and post-treatment.…”