Synthesis of redispersible spherical cellulose II nanoparticles decorated with carboxylate groups

Abstract

Cellulose II gels from a stream of the Lyocell fiber process were transformed into spherical nanoparticles by carboxymethylation and subsequent homogenization.

A General Aqueous Silanization Protocol to Introduce Vinyl, Mercapto or Azido Functionalities onto Cellulose Fibers and Nanocelluloses

“…3-Azidopropyl triethoxysilane was synthesized according to [ 6 ]. Carboxymethylated pulp with a DS of 0.06 was obtained from never-dried KZO3 pulp following the protocol of [ 25 ], the degree of substitution was measured by 1 H-NMR upon hydrolysis in D 2 SO 4 according to the literature [ 48 ]. Cellulose nanofibrils (CNF) were produced by passing a 1 wt% pulp (never-dried KZO3) slurry 20 times through a APV-1000 (SPX Flow Inc., Charlotte, North Carolina, United States) laboratory homogenizer at 800–900 bar.…”

Fabrication of regenerated cellulose nanoparticles by mechanical disintegration of cellulose after dissolution and regeneration from a deep eutectic solvent

“…15,16 Recently, TENCEL cellulose (obtained aer the dissolution and regeneration of cellulose from N-methylmorpholine-N-oxide (NMMO)) has been studied as a source of nanosized cellulose (spherical nanostructured cellulose gels and carboxymethylated SCNPs). 17,18 Compared to cellulose nanobers (CNFs) and cellulose nanocrystals (CNCs) which mostly have a cellulose I crystalline structure, regenerated cellulose has the crystalline structure of cellulose II. In addition, when regenerated cellulose is used as a source, the destruction of the ber structure leads to the production of nanoparticles with different morphologies (e.g., spherical) compared to those of nanocellulose obtained directly from a natural source.…”

Facile Synthesis of Highly Hydrophobic Cellulose Nanoparticles through Post-Esterification Microfluidization

“…CNPs with a low aspect ratio of close to 1 (here referred to as spherical CNPs) have attracted great interest, because they tend to be more stable than large aspect ratio cellulose nanomaterials such as CNFs and CNCs in solvent dispersions [5]. Currently, spherical CNPs are produced by acid hydrolysis [5,6], solvent method [3], enzymatic and mechanical treatment [7], and time-consuming chemical synthesis [8].…”

“…Introducing carboxylate groups into cellulose has many advantages in terms of functionalizing cellulose, facilitating mechanical fibrillation to produce cellulose nanomaterials, and increasing the stability of the resulting colloidal suspension in order to prevent aggregation [7]. It can also improve the cellulose hydrophobicity through carboxymethylation.…”

“…A simple PeM approach has been attempted using the Fischer-Speier esterification of hydroxyl groups, but this approach was not focused on producing highly hydrophobic CNPs. Rather, it was a chemical pretreatment step with a low DS of approximately 0.02-0.5, in order to reduce the energy in producing CNFs through subsequent mechanical fibrillation, or for producing esterified or carboxylated CNCs when using carboxylic acids or carboxylic anhydrides [7,[27][28][29][30][31]. The key to achieving highly hydrophobic CNPs using PeM is to achieve a high DS in the esterification of fibers.…”