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. 2023 Feb 1;123(5):1925–2015. doi: 10.1021/acs.chemrev.2c00611

Table 2. A List of Covalent and Noncovalent Methods for Decreasing Hydrophilicity of Nanocellulose.

altering the hydrophilicity of nanocellulose surfaces
surface modification reagents used required conditions role/consequence of water potential target application ref
Covalent Hydrophobization
esterification carbonyl chlorides, acid anhydrides anhydrous undergoes side reactions sensors, mechanical reinforcement, biomedical materials, (super)hydrophobic interfacial materials (487−493)
  darboxylic acids, active esters (potentially activating agents for in situ generation) anhydrous/aqueous reaction byproduct that decreases yields   (490)
           
darbamate formation isocyanate anhydrous causes side reactions polyurethane composites (494)
           
etherification alkyl chlorides anhydrous may cause phase separation, side reactions depending on substrates and reaction conditions introduction of functional groups, e.g., carboxymethylation (495−501)
  epoxides aqueous/anhydrous causes side reactions introduction of functional groups, e.g., quaternization (495−500)
chlorination (potential subsequent etherification) thionyl chloride anhydrous causes side reactions further modification  
           
oxidation (potential subsequent amination) periodate aqueous solvent further modification (503)
amidation EDC/NHS or comparable coupling agents, primary or secondary amines aqueous solvent selective modification, biomolecule immobilization (504−507)
amination aldehyde/keto-groups on cellulose, amines, reducing agent aqueous/anhydrous solvent protein immobilization (503,508)
           
silylation chlorosilanes anhydrous causes side reactions stable dispersion in organic media (509−511)
  alkoxysilanes anhydrous/aqueous solvent porous hydrophobic adsorbent materials (512,513)
           
polymer grafting (ATRP) ATRP-agent, vinyl monomers anhydrous/aqueous solvent tailor-made reinforced hydrogels (514,515)
polymer grafting (ROP) epoxides/cyclic lactones anhydrous chain transfer agent giving rise to bulk ROP covalent composite materials (416)
Noncovalent Hydrophobization
polymer adsorption hydrogen bond acceptors, countercharge carrying polymers, hemicelluloses anhydrous/aqueous dispersion medium, antisolvent thermoplastic polymer composite materials (516, 517, 518, 424, 519−528)
counterion exchange surfactants, quaternary ammonium ions, aqueous dispersion medium, antisolvent cellulose dispersion in nonpolar media (424, 522, 529−534)