TY - JOUR
T1 - Cationic polyacrylamide induced nanoparticles assembly in a cellulose nanofiber network
AU - Raghuwanshi, Vikram Singh
AU - Garusinghe, Uthpala Manavi
AU - Raj, Praveena
AU - Kirby, Nigel
AU - Hoell, Armin
AU - Batchelor, Warren
AU - Garnier, Gil
PY - 2018/11/1
Y1 - 2018/11/1
N2 - Polyacrylamides of different molecular weight, charges and dosages allow to control the retention and distribution of nanoparticles (NPs) in composites, and optimise composite properties and functionality. Our aim is to evaluate the effect of high molecular weight (13 MDa) cationic polyacrylamide (CPAM) charge and dosage on SiO2 (74 nm) NP's assembly in cellulose nanofibers composites. Engineered cellulose/SiO2 composites were investigated by SEM, SAXS and DLS. SEM images show the local area retention of NPs into the cellulose matrix. SAXS provides an average NPs distribution and inter-NPs distance over complete volume of composite. DLS gives the hydrodynamic radius of CPAM adsorbed onto SiO2 NPs in a suspension. SAXS analysis reveals a structure conformation made of spherical SiO2 NPs core of diameter 74 nm surrounded by a CPAM polyelectrolyte shell 2.5 nm thick. Surprisingly, CPAM induced assembly of SiO2 NPs with constant inter-nanoparticle distance, which is irrelevant of polymer charge density. However, NPs retention in the cellulose fibre network increases with CPAM dosage. The assembly mechanism is governed by the balance of electrostatic and steric forces following CPAM coverage onto NPs and the inter-nanoparticle CPAM bridging conformation. This maintains the constant inter-nanoparticle distance and the assembly of NPs in the cellulose network.
AB - Polyacrylamides of different molecular weight, charges and dosages allow to control the retention and distribution of nanoparticles (NPs) in composites, and optimise composite properties and functionality. Our aim is to evaluate the effect of high molecular weight (13 MDa) cationic polyacrylamide (CPAM) charge and dosage on SiO2 (74 nm) NP's assembly in cellulose nanofibers composites. Engineered cellulose/SiO2 composites were investigated by SEM, SAXS and DLS. SEM images show the local area retention of NPs into the cellulose matrix. SAXS provides an average NPs distribution and inter-NPs distance over complete volume of composite. DLS gives the hydrodynamic radius of CPAM adsorbed onto SiO2 NPs in a suspension. SAXS analysis reveals a structure conformation made of spherical SiO2 NPs core of diameter 74 nm surrounded by a CPAM polyelectrolyte shell 2.5 nm thick. Surprisingly, CPAM induced assembly of SiO2 NPs with constant inter-nanoparticle distance, which is irrelevant of polymer charge density. However, NPs retention in the cellulose fibre network increases with CPAM dosage. The assembly mechanism is governed by the balance of electrostatic and steric forces following CPAM coverage onto NPs and the inter-nanoparticle CPAM bridging conformation. This maintains the constant inter-nanoparticle distance and the assembly of NPs in the cellulose network.
KW - Assembly
KW - Cationic polyacrylamide (CPAM)
KW - Cellulose
KW - Dynamic Light Scattering (DLS)
KW - Nanoparticles
KW - Scanning Electron Microscopy (SEM)
KW - Silica (SiO)
KW - Small Angle X-ray Scattering (SAXS)
UR - http://www.scopus.com/inward/record.url?scp=85048221972&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2018.06.009
DO - 10.1016/j.jcis.2018.06.009
M3 - Article
C2 - 29894936
AN - SCOPUS:85048221972
SN - 0021-9797
VL - 529
SP - 180
EP - 186
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
ER -