Polyamide-amine-epichlorohydrin (PAE) induced TiO₂ nanoparticles assembly in cellulose network

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Science

Background:

• The functionality of TiO2-NPs-Cellulose composites is critically dependent on the effective retention and dispersion of TiO2 nanoparticles (NPs) within the composite matrix.
• Understanding the influence of poly(acrylic acid ethyl ester) (PAE) on NP aggregation, retention, and interaction mechanisms is crucial for optimizing composite properties.

Purpose of the Study:

• To investigate the effect of PAE dosage on the aggregation state, retention, and interaction mechanisms of TiO2 NPs in cellulose-based composite sheets.
• To determine the optimal PAE dosage for achieving desired NP dispersion and retention in TiO2-NPs-Cellulose composites.

Main Methods:

• TiO2-NPs-Cellulose composite sheets were fabricated using suspensions with varying PAE dosages (10 and 50 mg PAE/g fibers) and different TiO2 NP loadings.
• Scanning Electron Microscopy (SEM) and Small-Angle X-ray Scattering (SAXS) were employed to quantify NP retention and assess the aggregation state of TiO2 NPs within the cellulose matrix.

Main Results:

• PAE dosage influences cellulose fiber surface coverage, with 20 mg/g providing full coverage and 50 mg/g resulting in excess free PAE.
• Surprisingly, TiO2 NP aggregation was observed at both PAE dosages, with aggregate size increasing with NP loading.
• The retention and aggregation state of NPs remained similar across different PAE dosages, suggesting complex PAE-NPs bridging mechanisms.

Conclusions:

• PAE influences the surface coverage of cellulose fibers but does not prevent TiO2 NP aggregation in cellulose composites.
• The aggregation and retention of TiO2 NPs are primarily governed by NP loading and complex interfacial interactions rather than solely by PAE dosage.
• Further research into PAE-NPs bridging mechanisms is needed to control NP dispersion and enhance composite functionality.