Cationic and anionic polyelectrolyte complexes of xylan and chitosan. Interaction with lignocellulosic surfaces

Area of Science:

• Polymer Science
• Materials Science
• Biotechnology

Background:

• Xylan and chitosan are natural polysaccharides with potential applications in papermaking.
• Polyelectrolyte complexes (PECs) offer tunable properties for material modification.
• Improving paper properties like strength is crucial for the paper industry.

Purpose of the Study:

• To form and characterize cationic (CatPECs) and anionic (AnPECs) polyelectrolyte complexes from xylan and chitosan.
• To investigate the adsorption behavior of these PECs onto cellulosic surfaces.
• To evaluate the impact of adsorbed PECs on the papermaking properties of unbleached fibers.

Main Methods:

• PECs were prepared by varying polyelectrolyte addition order and ionic strength (0.01N and 0.1N NaCl) at 30% neutralization.
• Characterization included charge density (titration), colloidal stability (Turbiscan), particle size (Zetasizer Nano), and structure (DRIFT).
• Adsorption was studied using quartz crystal microbalance with dissipation monitoring and surface plasmon resonance on cellulose nanofibril surfaces.

Main Results:

• Stable CatPECs and AnPECs were formed, exhibiting viscoelastic and highly hydrated characteristics upon adsorption.
• The adsorption of PECs onto cellulose nanofibrils was successfully demonstrated and quantified.
• Paper made with adsorbed PECs showed marked improvements in tensile and crushing strengths.

Conclusions:

• Xylan-chitosan polyelectrolyte complexes are effective modifiers for cellulosic fibers.
• The viscoelastic and hydrated nature of adsorbed PECs contributes to enhanced paper properties.
• This study demonstrates a viable method for improving paper strength using biopolymer-derived PECs.