Water-based Polymeric Adhesives With Super-high Bonding Strength

Adhesives that can bond two pieces of separated substrates together play an important role in human life.At present,most of the developed polymer adhesives were solvent-based ones because of their super-high adhesion strength and fast solidification speed.However,the solvent-based adhesives would generally release massive volatile organic compounds（VOC）or toxic reagents during the process of use and drying,causing severe environment and health problems.Therefore,it is highly desirable to develop green and environment friendly water-based polymer adhesives to substitute solvent-based adhesives.So far,various strategies have been developed to prepare water-based adhesives,however,these developed adhesives either had a relatively low bonding strength or required a complexed synthesis process,which limited the widely applications of the water-based adhesives.Therefore,it is highly desirable to develop facile and cost-effective methods to achieve the large-scaled preparation of water-based adhesives with super-high bonding strength and substrate-independency.In this thesis,two preparation methods（one-step hydrolyzing method and one-step polymer complexing method）were developed to realize the facile and cost-effective preparation of water-based adhesives that had super-high bonding strength,and meanwhile,can be applied to various substrates.The specific works of this thesis are as follows:1.A one-step hydrolyzing of polymethyl methacrylate（PMMA）method was developed to obtain water-based polymeric adhesives with super-high bonding strength and substrate-independency.The poly（methacrylic acid-co-methyl methacrylate）（P（MAA-MMA））with different hydrolysis degree was prepared by hydrolyzing of polymethyl methacrylate（PMMA）in alkali solution with different concentration.The P（MAA-MMA）with both hydrophobic and hydrophilic groups within their polymer chains can be used as adhesives.And the bonding strength of the P（MAA-MMA）adhesives can be controlled by adjusting the hydrolysis degree of the PMMA in alkali solution because on one hand,the polymer chains of P（MAA-MMA）can be driven to agglomerate and intertwine with each other based on the hydrophobic-hydrophobic interactions,which worked as the cohesion of the adhesives.On the other hand,the supramolecular interactions between the carboxyl groups of P（MAA-MMA）and the hydrophilic substrates played an important role as the adhesion of the adhesives.The results showed that the P(MAA₆₆-MMA₃₄)has the strongest bonding strength of 5.85±1.03 MPa on metal substrates;1.17±0.52 MPa on polymer substrates and 4.22±1.86 MPa on wood.The bonding strength of P(MAA₆₆-MMA₃₄)was higher than most of the developed water-based adhesives.The P(MAA₆₆-MMA₃₄)adhesive was papered by a facile and efficient strategy,and has high bonding strength and can be applied on diverse substrates.More importantly,the raw materials to prepare the water-based P(MAA₆₆-MMA₃₄)adhesive can be the recycled PMMA waste,which not only can largely decrease the preparation costs,but significantly contribute to construct the sustainable society.2.A water-based P(MAA₆₆-MMA₃₄)/poly（diallyldimethylammonium chloride）（PDDA）adhesive with super-high bonding strength and substrate-independency was prepared by simply mixing P(MAA₆₆-MMA₃₄)and PDDA in alkaline water solution.The cohesive of P(MAA₆₆-MMA₃₄)/PDDA adhesive was provided by electrostatic interactions between P(MAA₆₆-MMA₃₄)and PDDA,while the net positive or negative groups within the complexes provided the adhesion of the adhesive.By adjusting the mixing ratio between P(MAA₆₆-MMA₃₄)and PDDA in the complexes,the balance between the adhesion and cohesion of the adhesive can be tailored.The P(MAA₆₆-MMA₃₄)₅/PDDA₅ has the highest bonding strength of 6.61±2.25 MPa on metal substrates,7.43±0.85 MPa on the glasses,7.82±0.44 MPa on wood and 1.12±0.10 MPa on polymer substrates,which were all comparable with that of 3M epoxy glue.Besides the high bonding strength,the P(MAA₆₆-MMA₃₄)₅/PDDA₅adhesives also exhibited excellent stability in water.After complete immersion in water for six months,the bonding strength of the adhesive can still maintain 80%of its original strength.3.A transparent water-based adhesive with super-high bonding strength and substrate-independency was developed by simply mixing polyacrylic acid（PAA）and PDDA in solution.The electrostatic interactions between the PAA and PDDA provided the cohesion of the adhesive,while the net positive or negative groups within the PAA/PDDA complexes worked as the adhesion to the surface of the substrates.By adjusting the mixing ratio between PAA and PDDA,the cohesion and adhesion of the adhesive to diverse substrates can be tailored.And the synergistic of the cohesion and adhesion of the adhesive made the PAA₄/PDDA₆ complexes had the highest bonding strength of 7.49±3.14 MPa on metal sheets,12.40±0.87 MPa on glasses,6.27±1.12 MPa on wood and 1.56±0.73 MPa on polymer substrates.The bonding strengths of the PAA₄/PDDA₆ complexes were all comparable with that of the 3M epoxy glue.The bonding strengths of the PAA₄/PDDA₆ adhesives to metal and glass were even higher than that of the 3M epoxy glue.At the same time,the PAA₅/PDDA₅ adhesives also exhibited high transparency.Moreover,the PAA₅/PDDA₅ adhesive also possessed excellent stability in water.After complete immersion in water for three months,the bonding strength of the PAA₄/PDDA₆adhesives to iron sheets was even increase to 145%of their original strength after drying.