Hydrogen-bonding-induced assembly of aligned cellulose nanofibers into ultrastrong and tough bulk materials

Abstract

Structural materials with exceptional strength and toughness are assembled through water induced hydrogen bonding among cellulose nanofibers, providing significant finding that water can serve as structural molecules to bridge natural polymers.

A reproducible method to characterize the bulk morphology of cellulose nanocrystals and nanofibers by transmission electron microscopy

“…On the other hand, there is a very different behavior observed for CNF-T and CNF-M. As observed in Fig. 1c, CNF-T suspension was deposited onto the grid surface building up an interconnected network structure (Han et al 2019). In this way, it seems that the presence of holes did not affect to the deposition of Fig.…”

Cellulose Nanofibrils Enhanced, Strong, Stretchable, Freezing‐Tolerant Ionic Conductive Organohydrogel for Multi‐Functional Sensors

“…In addition, CNFs play a critical role in reinforcing the organohydrogel, by forming hydrogen bond and/or physical entanglement with PVA chains as well as themselves, which can dissipate energy during deformation through dynamic hydrogen bond formation. The formation of hydrogen bonds between CNF and PVA could be proved by the shifting of stretching vibration of hydroxyl groups of PVA (3278 cm −1 ) and CNF (3353 cm −1 ) [ 35 ] to a lower frequency of 3240 cm −1 for the PVA‐4% CNF (Figure S4, Supporting Information), since the original ‐OH bond in PVA is weakened by the hydrogen bond, requiring less energy for vibration. [ 36 ] Surprisingly, the CNF reinforced PVA organohydrogel shows simultaneous increase in both strength and toughness, which is commonly deemed as a material dilemma.…”

Delignified Wood from Understanding the Hierarchically Aligned Cellulosic Structures to Creating Novel Functional Materials: A Review

“…It is very important to freeze-dry the DW to maintain the stability of the naturally aligned cellulosic structure and the natural porosity and pore size for the development of various functional materials. In another study, Han et al [105] investigated the water vapor sorption behavior in a desiccator containing saturated potassium sulfate (K 2 SO 4 ) solution (97.6 ± 0.5%, under relative humidity at 20 °C) of DW samples that were dried in three different conditions (air-drying, solvent exchange-drying, and freeze-drying). All three types of dried DW samples showed gradually increased water vapor uptake over 96 h and followed a decreasing trend for freeze-dried (19.4 ± 0.1%), solvent exchange-dried (18.3 ± 0.6%), and air-dried (16.8 ± 0.3%).…”

“…Han et al [105] investigated how aligned cellulose fibrils interact with each other via hydrogen bonding to form compressed Figure 6. SEM images of a-c) native wood, d-f) beech wood after mild delignification and oven-drying, g-i) beech wood after harsh delignification and oven-drying, and j-l) beech wood after harsh delignification and freeze-drying, and m,n) effect of the extent of delignification (mild (60 °C, 8 h) and harsh (80 °C, 4 h)) and drying process (freeze-drying and oven-drying) on the porosity of beech wood expressed as cumulative pore volume and a histogram of the relative pore volume as a function of the pore radius.…”