Starch is a highly attractive carbohydrate in the production for the preparation of adhesives in recent years, due to its widespread availability, renewability, and abundance of reactive hydroxyl groups. However, the mechanical properties, hydrophobicity , self-adhesion, and particularly high energy efficiency are generally unsatisfactory for current starch-based adhesives. On this premise, starch was oxidized using Fenton's reagent in a "“one-pot cooking” process. The prepared oxidized starch was chain expanded by polyvinyl alcohol (PVA) and then cross-linked with a 10 % isocyanate (PM-200) to fabricate a starch-based adhesive (SFA) with a network crosslinked structure. SF 12 A 35% /2.5-55 adhesive shows significantly higher wet shear strength (1.18 MPa), a remarkable 94 % increase compared to SF 0 A 35% /2.5-55. The adhesive film also demonstrates both hydrophobicity (99° contact angle) and exceptional energy efficiency, with a DSC test revealing a notable 10 % elevation in energy efficiency. In addition, the crosslinked structure increases its molecular weight, thereby increasing its self-adhesion (Fig. S1). This study opens up new possibilities for the design and manufacture of multifunctional starch-based adhesives.
The graft copolymerization of eucalyptus lignosulfonate calcium (HLS-Ca) from hardwood and acrylic acid (AA) was investigated by using Fenton agent as a coinitiator. The influences of reaction conditions on grafting parameters i.e. product yield ( Y %), AA conversion ( C %), grafting ratio ( G %) and grafting efficiency (GE%) were carefully studied. The effects of the phenolic hydroxyl (Ph-OH) group on the polymerization of AA and grafting reaction were researched. Graft copolymers were identified by the new absorption at 1727 cm −1 , more homogenized morphology and higher decomposition temperature after grafted with AA, as illustrated in FTIR, SEM and TG spectra. The optimum synthesis conditions are as follows: H 2 O 2 = 25.2 mol/L, FeCl 2 = 63.0 mol/L, T = 50 °C and t = 2 h and the optimum percentages of Y , C , G and GE are 97.61%, 95.23%, 71.29% and 78.85%, respectively. The Ph-OH group of HLS-Ca cannot inhibit the polymerization of AA and is involved in the grafting reaction as an active center.