Assembly of nanoparticles-polyelectrolyte complexes in nanofiber cellulose structures

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2017-01, Vol.513, p.373-379
• Main Authors: Garusinghe, Uthpala M., Raghuwanshi, Vikram S., Garvey, Christopher J., Varanasi, Swambabu, Hutchinson, Christopher R., Batchelor, Warren, Garnier, Gil
• Format: Article
• Language: English
• Subjects: Cationic polyacrylamide (CPAM); Composites; fibres; Nanocellulose; Silica nanoparticles (NPs); Small angle X-ray scattering (SAXS); TEM
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2016.10.068

[Display omitted] •We quantify the effect of cationic polyacrylamide (CPAM) dosage on the assembly of silica nanoparticles (NPs) within a nanocellulose composite.•Increasing CPAM dosage increases retention of NPs within the cellulose matrix with stronger interparticle interactions.•Small angle X-ray scattering (SAXS) and microscopic reveal that CPAM concentration affects the aggregates size of SiO2 NPs within the composite.•We show a bimodal distribution of spherical particles (8–20nm in diameter) in nanocellulose composites by modelling the SAXS curves.•Data analysis allow understanding interparticle interactions within assemblies of SiO2 NPs at the nanometer scale with different dosage of CPAM. We report the effect of cationic polyacrylamide (CPAM) addition on the structural assembly of silica nanoparticles (NPs) within a nanocellulose fibre matrix. Paper like composites are fabricated by first forming complexes of NPs with CPAM, then adding those to a suspension of nanocellulose fibres; followed by filtration, pressing and drying of the final suspension. Complementary small angle X-ray scattering (SAXS) and microscopy (SEM, TEM) investigations of these composites showed a lognormal bimodal distribution of NP sizes. Data analysis allows understanding interparticle interactions within assemblies of SiO2 NPs at the nanometer scale with respect to different dosage of CPAM. Increasing CPAM dosage increases retention of NPs within the cellulose matrix with stronger interparticle interactions and produces composites with smaller pores. The correlation length of NPs, indicative of the size of the NP clusters increased from 30 to 70nm as the CPAM dosage increased from 16.5 to 330mg/g NPs. Retention and assembly of SiO2 NPs by varying CPAM dosage results from the balance of different interaction forces between NPs, CPAM and nanocellulose fibres. Understanding the effect of CPAM dosage on the various NP and composite structural conformations enables us to engineer novel hierarchically and functional cellulose based structured materials.