Table 2.

Information from some of the latest reports on the synthesis of hollow nanoparticles/nanocapsules of lignin.

Type of Lignin Used and Structure Formed	Method Used	Mechanism Suggested	Reported by
Ultrasonic Assisted Synthesis
Dioxane soluble fragment of alkali lignin, hollow colloid	Ultrasonic spray-freezing	Peripheral precipitation	[10]
Kraft lignin, microcapsules	Ultrasound driven self- association	Ultrasound-mediated cross-linking	[82]
Kraft lignin, nanocapsules	Ultrasonication of microemulsion	Ultrasound-induced self-assembly and complexation	[83]
Kraft lignin, hollow nanospheres	Ultrasonication assisted solubilization, anti-solvent addition	Self-assembly at two different phases	[84]
Wheatgrass lignin and Sarkanda grass lignin	Ultrasonication of aqueous suspension	Side chain cleavage/depolymerization and oxidative coupling/polymerization	[85]
Homogenization assisted synthesis
Organosolv lignin residue, submicron spheres	Homogenization enhanced nucleation	Hydrophilic-lipophilic aggregation	[86]
Change of pH and/or solvent
Enzymatic hydrolytic lignin, single hole nanospheres	Solvent-anti-solvent precipitation method	Layer by layer self- assembly outside to inside	[42]
Kraft lignin, nanocapsules	Solvent-anti-solvent precipitation method	Spontaneous distribution of hydrophilic-lipophilic sequences	[87]
Softwood Kraft lignin, lignin Nanoparticles	Anti-solvent addition using dialysis bag	Chemical precipitation	[55]
lignin nanocontainer	Interfacial polyaddition	Polyaddition reaction at interface	[88]
Enzymatic hydrolytic lignin, solid nanospheres	Solvent–anti-solvent precipitation method	Layer by layer self-assembly inside to outside	[41]
Kraft lignin, nanospheres	Solvent-anti-solvent precipitation method	Chemical precipitation	[89]
Low sulfonated lignin (indulin AT)	Solvent-anti-solvent and base-acid precipitation	Chemical precipitation	[81]
Kraft lignin	DMF (solvent)-compressed CO2 (anti-solvent)	Expansion by anti-solvent	[90]