Preparation of high-performance cellulose composite membranes from LiOH/urea solvent system

Abstract

New green solvent system alkali (such as NaOH and LiOH)/urea which could rapidly dissolve cellulose could be potentially used to prepare high-performance regenerated cellulose materials with low cost. Pure regenerated cellulose materials have relatively low strength inherent effects. In this work, we choose TEMPO-oxide cellulose nanofiber (CNF) and graphene oxide (GO) as fillers to prepare isotropic regenerated cellulose membrane (RCM) with significantly enhanced mechanical properties. Dynamic mechanical analyzer (DMA) test shows that RCM with content of 5 wt% CNF has the maximum enhancement value of 32.5% improvement comparing with pure RCM. And RCM with 0.4 wt% GO has the maximum improvement of 17.9%. Mechanical properties decrease with further increasing filler contents. We employ transmission electron microscopy to confirm the structure of fillers in solution and scanning electron microscopy to observe the microstructures of these RCMs. The results are consistent with DMA tests. In addition, XRD results confirm that the crystal structure of RCMs is the same with RCMs without filler. Thermogravimetric analyses results indicate that RCMs keep great thermal stability below 300 C. Transmittance (T r ) property is carried out by UV-Vis spectroscopy. Pure RCMs and CNF/RCMs keep high transparency at the wavelength of 800 nm. Transparency of RCMs with GO decrease quickly when the content of GO increases. In conclusion, the enhancement mechanism is proposed as the addition of fillers makes up the defects in RCMs. Furthermore, CNF illustrates large aspect ratio which is beneficial for stress transfer. As for GO, polar groups on surface provide strong interaction with the matrix. This is the first time that the enhancement effects of different fillers are systematically analyzed and compared for RCMs system. Our work could benefit the selection of appropriate fillers for such green solvent system and expand its range of applications.

Toward the Next Generation of Sustainable Membranes from Green Chemistry Principles

“…However, its high crystallinity and strong intermolecular hydrogen bonds reduce the solubility in common solvents, limiting the membrane fabrication. 71 The solvents that have been used to obtain cellulose-based membranes are listed in Table 1.…”

Implementation of Epoxy Resin Composites Filled with Copper Nanowire-Modified Boron Nitride Nanosheets for Electronic Device Packaging

“…Compared to the direct mixing of thermally conductive fillers, a more effective thermal conductivity network can be formed within the polymer matrix by constructing thermal conductive fillers with special morphologies. − Lu et al fabricated zinc hydroxystannate nanocubes in situ on the surface of titanium carbide (Ti 3 C 2 T x ) MXene nanosheets to form a zero–two-dimensional (0D–2D) layered structure . This ER composite exhibited a thermal conductivity of 0.8691 W/m K, a substantial 3.2-fold enhancement compared to pure ER.…”

Surface functionalization of nylon 66 membrane using para-phenylenediamine and carboxylic functionalized multi-walled carbon nanotubes for removal of calcium ions from aqueous solution

“…Among them, the ultrafiltration and nanofiltration are usually used for early steps to separate and/or purify chitin from raw protein solution. Commonly used membranes in these methods are porous polymeric films or the thin film composites (TFCs) based on them [6][7][8][9][10][11][12][13][14][15][16]. Liquid flows, including semi-finished or finished liquids, washing water, wastewater, are pumped and returned to high pressure in the production line [9][10][11][12].…”

“…Multilayered TFN membranes are often casted from nanocomposites or formed directly during the polymerization of the precursors. Nanomaterials are dispersed in thin films to generate or improve mechanical, chemical and special properties combined from different groups of materials (such as hydrophilic properties, creating interactive forces, static electricity, adsorption capacity, specific surface area, … ) [7,10,[13][14][15][16][17][18][19][20][21][22][23][24]. Therefore, multilayered TFN membranes have a diverse range of segregation, according to the purpose of use, and enhanced anti-fouling features.…”

“…Polymeric membranes are more widely developed than the rest of the materials due to their low production costs, mass production and flexible applications [5,19]. Types of polymer materials commonly used to make membranes include polytetrafluoroethylene (PTFE) [21,23], polyvinylidene fluoride (PVDF) [9,11,13,23], polyamide (PA) [14,15,17,19,21], polysulfone (PSF) [14,15,17,24], polyethersulfone (PES) [15,19,20], polyetherimide (PEI) [11,15,24], polystyrenes (PS) [14], polyvinyl alcohol (PVA) [14,16], … Among such materials, PA based thin-film nanocomposite (PA-TFC) are commonly used as either forward osmosis (FO) or reverse osmosis (RO) membranes due to their high separation efficiency, high mechanical strength and environmental friendliness [23,24]. However, the fouling is easily caused by hydrophobicity of the active PA layer as well as uncertain retention time of components on rough walls of pores.…”