Controlling Miscibility of the Interphase in Polymer-Grafted Nanocellulose/Cellulose Triacetate Nanocomposites

Abstract

The miscibility at the interphase of polymer-grafted nanocellulose/cellulose triacetate (CTA) composite films was tailored using different casting solvents. The polymer-grafted cellulose nanofibrils were prepared by modifying surfaces of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized nanocellulose with amine-terminated poly(ethylene glycol) (PEG). The PEG-grafted nanocelluloses were individually dispersed in dichloromethane, 1,4-dioxane, and N , N -dimethylacetamide. The PEG-grafted nanocellulose/CTA composite films were prepared by mixing the nanocellulose dispersion and CTA solution and subsequent casting-drying. The miscibility of PEG and CTA at the interphase of the composite was controlled by controlling the solvent, which was confirmed by dynamic mechanical analysis. All the composite films showed high optical transparency. However, the mechanical properties of the composites differed because of the difference in the PEG/CTA interfacial miscibility. The composite films with better PEG/CTA interfacial miscibility showed higher Young’s modulus, strength, and toughness. This interfacial design technique paves the way to exploiting the reinforcing potential of highly transparent and hydrophobic surface-grafted nanocellulose/polymer composite materials.

Understanding Nanocellulose–Water Interactions: Turning a Detriment into an Asset

“…In this section, we focus on surface modification approaches that aim to decrease the hydrophilicity of nanocelluloses and the role of water in these reactions. This often-termed “hydrophobization” of nanocellulose leads to the disruption of the solvation of surface structures by water by capping the available hydroxy groups through the attachment of hydrophobic moieties, − grafted polymers, − or even nanoparticles. − Generally, the reasons to hydrophobize the surface of nanocellulose include increasing the hygromechanical stability (keeping good mechanical properties in the wet state), improving the compatibility with hydrophobic polymers or solvents or reducing the effects of hornification upon drying. ,− The palette of the available modification pathways is very diverse, and a full review of these reactions is out of the scope of this paper. The reader is encouraged to follow the details of modification reactions in the previous publications on this topic. , , , , , , ,, , , , , , , − However, a short overview of the most important routes to nanocellulose surface hydrophobization is covered here and summarized in…”

Fabrication of Highly Interconnected Poly(ε-caprolactone)/cellulose Nanofiber Composite Foams by Microcellular Foaming and Leaching Processes

“…Cell growth will cause pore structure with interconnected pores. 13 Polymer nanocomposites are described as polymers that contain fillers lower than 100 nm in at least one dimension 14 usually adding nanodimensional fillers to the polymer, PLA, 15 TPU, 16 and PA. 17 In most cases, low interconnectivity results are obtained based on scCO 2 foaming because the gas expansion force is too small to overcome the strength of the polymer matrix. 18 Particle leaching is an effective process for fabricating highly interconnected porous structures.…”

“…Cell growth will cause the two-phase interface to separate from each other, forming an open-pore structure with interconnected pores . Polymer nanocomposites are described as polymers that contain fillers lower than 100 nm in at least one dimensionusually adding nanodimensional fillers to the polymer, PLA, TPU, and PA …”

Dispersibility of freeze-drying unmodified and modified TEMPO-oxidized cellulose nanofibrils in organic solvents

“…-poly(ethylene glycol) (PEG)-grafted TOCNF-COO were individually dispersed in chloroform, toluene, dichloromethane, 1,4-dioxane, DMA [15][16][17]; -n-dodecylamine-modified TOCNF-COO were dispersed at the level of individual nanofibrils in isopropyl alcohol [18]; -cetyltrimethylammonium bromide-modified TOCNFs demonstrated increased hydrophobicity and improved redispersibility in DMF [19]; -TOCNFs, modified with tannic acid and hexadecylamine, were dispersed in toluene, ethanol, acetone [20]; -TOCNF-COO with amphiphilic diblock copolymer-modified surface exhibited an increased dispersibility in such organic solvents as DMSO, DMF, ethanol, and methanol [21]. It should be noted that the aforementioned solvent exchange process is quite laborious because of the use of intermediate solvents and multiple centrifugation cycles.…”