Improved starch adhesives for packaging and wood products

Abstract This study addresses the growing demand for sustainable and non‐toxic adhesives by developing a polysaccharide polyelectrolyte complex (PPC) adhesive using starch polyelectrolytes. A turbidity test was used to formulate the starch PPC, which demonstrated significant improvements in water and grease resistance through the complexation of anionic and cationic starches, with water resistance increasing by 93.2%. Applying 10 g/m 2 of starch PPC provided adequate adhesion strength for paper substrates and achieved a joint strength of approximately 4.5 MPa on wood. However, no significant differences were observed between starch PPC and neat starch for wood adhesion, highlighting inadequate bonding. While starch PPC showed enhanced water resistance, bonded wood samples had superior wet strength with cationic starch due to ionic pairing between the starch and wood. Contact angle measurements revealed lower wettability of starch PPC on wood, indicating weaker surface attachment and adhesion strength. These results emphasize the need for further optimization of starch‐based adhesives to improve their performance while maintaining environmental sustainability. Highlights UV–Vis light transmittance optimizes starch‐based PPC composition. Shear‐thickening behavior was detected in starch both before and after complexation. Starch PPC showed a 93.2% improvement in water resistance versus neat starch Starch PPC demonstrates adequate strength as an effective paper adhesive. Starch PPC adhesive achieved a shear strength of 4.5 MPa with wood substrates.