A green preparation method: ARGET ATRP method for the preparation of pressed plywood with soy protein adhesive

With the continuous reduction of petroleum resources, synthetic adhesives based on petrochemical products will face the problem of resource shortage. Soy protein is an environmentally friendly biobased material, but it has problems with poor water resistance and poor permeability. Pretreatment of soy protein with green deep eutectic solvent (DES) exposed hydrophobic groups and active sites. Through the measurement of infrared and ultraviolet spectra, the hydrogen bonds of soybean protein pretreated with DES were disrupted, the content of amino acid residues inside the sphere increased, the water contact angle changed from 46.3° to 88.5°, and the hydrophobicity was enhanced. After pretreatment, functional monomers were introduced into modified soy protein and bromine functional groups were introduced to prepare soy protein isolate bromide (SPI-Br) initiator. Through the activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) method, glycidyl methacrylate (GMA) was grafted onto the molecules of soy protein. By controlling the redox reaction of the catalytic system, controllable radical polymerization technology was achieved. This method reduces the influence of oxygen on the reaction and makes the reaction conditions relatively relaxed. Through infrared spectroscopy and nuclear magnetic resonance characterization testing, soy protein isolate-graft-Poly(glycidyl methacrylate) (SPI-g-PGMA) was successfully prepared. By optimizing the hot pressing process through response surface methodology, the bonding strength of plywood can reach 1.090 MPa, which is higher than the set value for Class II plywood using standard testing methods. This method has the advantages of green and environmental protection, making the soy protein copolymer prepared by this method have good industrial application prospects in green and environmental protection. • Preparation of bio-based adhesives from soybeans to alleviate the oil crisis. • Green low eutectic solvent, improve hydrophobicity and amino acid residue. • Gluing strength meets national standards, suitable for green industrial applications.