Phosphonated nanocelluloses from sequential oxidative-reductive treatment-Physicochemical characteristics and thermal properties.
Nanocellulosic materials with good thermal stability are highly desirable for applications, such as reinforcement and filler agents in composites. In the present work, phosphonated cellulose was utilized to obtain nanocelluloses with good thermal stability and potential intumescent properties. Phosphonated cellulose was synthetized from birch pulp via sequential periodate oxidation and reductive amination using a bisphosphonate group-containing amine, sodium alendronate, as a phosphonating reagent. After high-pressure homogenization, bisphosphonate cellulose nanofibres or nanocrystals were obtained, depending on the initial oxidation degree. Nanofibres had a typical diameter of 3.8nm and length of several micrometers, whereas nanocrystals exhibited a width of about 6nm and an average length of 103-129nm. All nanocelluloses exhibited cellulose I crystalline structures and high transparency in water solutions. Phosphonated nanocelluloses exhibited good thermal stability and a greater amount of residual char was formed at 700°C compared to birch pulp and mechanically produced, non-chemically modified NFC.
Fibre and Particle Engineering Laboratory, University of Oulu, PO Box 4300, Oulu FI-90014, Finland. Electronic address: juho.sirvio@oulu.fi.
Juho Antti
JA
Sirviö
Department of Chemistry, University of Oulu, PO Box 3000, Oulu FI-90014, Finland. Electronic address: timo.hasa@student.oulu.fi.
Tapani
T
Hasa
Department of Process and Environmental Engineering, University of Oulu, PO Box 4300, FI-90014 Oulu, Finland. Electronic address: juha.ahola@oulu.fi.
Juha
J
Ahola
Fibre and Particle Engineering Laboratory, University of Oulu, PO Box 4300, Oulu FI-90014, Finland. Electronic address: henrikki.liimatainen@oulu.fi.
Henrikki
H
Liimatainen
Fibre and Particle Engineering Laboratory, University of Oulu, PO Box 4300, Oulu FI-90014, Finland. Electronic address: jouko.niinimaki@oulu.fi.
Jouko
J
Niinimäki
Department of Chemistry, University of Oulu, PO Box 3000, Oulu FI-90014, Finland. Electronic address: osmo.hormi@oulu.fi.
Osmo
O
Hormi
D002482:Cellulose / Q000737:chemistry*; D055598:Chemical Phenomena; D007700:Kinetics; D057139:Nanofibers / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010757:Phosphorous Acids / Q000737:chemistry*; D013696:Temperature
D010757:Phosphorous Acids; C570063:phosphonic acid; D002482:Cellulose
2-picoline borane (PubChem CID: 7975); Bisphosphonate; Nanocellulose; Periodate oxidation; Reductive amination; Sodium alendronate (PubChem CID: 16760285); Sodium periodate (PubChem CID: 23667635); Thermal properties; lithium chloride (PubChem CID: 433294)