Studies On Synthesis And Properties Of Polyurethane Adhesives With Dopamine

Mussel Adhesive Proteins (MAPs) secreted by marine mussels allow themselvesto anchor tenaciously to all types of inorganic and organic surfaces in a wet andturbulent environment,such as metal,glass, polymer, and mineral surfaces,evenincluding adhesion-resistant poly(tetrafluoroethylen). MAPs exhibit goodbio-compatibility, bio-degradation and non-toxic property, which will not invade cellsin bodies or trigger the body’s immune response. A common character of the MAPs isthat they possess a relatively high level of L-3,4-dihydroxyphenylalanine (DOPA), acatabolic amino acid produced from post-thanslational modification of tyrosine.Research carried out by other groups suggests that the catechol group in DOPA playsan important role in enhancing interfacial adhesion. However, this kind of musseladhesive was confined by ultra-low production, complex technology, and high costthrough extraction or recombinant DNA approach. Therefore, it’s meaningfulintroduce the adhesive functional group of MAPs into the suitable synthetic polymerto prepare bionic mussel adhesive polymeric materials.Ideally, it is possible to prepare a mimetic adhesive polymeric material of lowcost and high property while combining the unique adhesion of marine adhesiveproteins with the designability and easy synthesis of simple polymer. In this thesis,mainly deal with synthesis of dopamine-containing polyurethane chain extender andthe application in the synthesis of dopamine-containing polyurethane, associated withstructural characterization and performance analysis.Firstly, one new-type polyurethane chain extender （DMPA-DA） whichcontaining dopamine was successfully synthesized through four chemical reactions,then reaction with the NCO-terminated urethane prepolymer, finally three series ofpolyurethane with different contents of dopamine were synthesized by changing theratio between DMPA-DA and another chain extender-1,4butanediol. The structure of the novel chain-extender and the novel polyurethane was characterized by FT-IR、~1H-NMR、GPC、Uv-vis.TGA results show that decomposition temperature of dopamine-containingpolyurethane’s hard segment was decreased when dopamine content increased, andcarbon residue quantity increased in accord with increase of the dopamine content;Shear adhesive strength of dopamine-containing polyurethane hot melt adhesives wasincreased in accord with increase of the curing temperature.Shear adhesive strength test results show that: as for the substrate of PP, itbelongs to the interface fracture, the shear adhesive strength was increased in accordwith the contents of dopamine in the polyurethane; as for the other substrates (e.g.LDPE, Al, stainless steel), belongs to the interaction between ontology fracture andinterfacial fracture, dual affected by the molecule weight and the dopamine content.Shear adhesive strength test results on different substrates show that the introductionof dopamine into polyurethane improved the adhesion ability greatly for differentsubstrates: increased by152%on PP, increased by94%on LDPE, increased by258%on Al, increased by102%on stainless steel. BWT and WSAD test results show thatthe introduction of dopamine can improve polyurethane’s waterproof adhesion ability.Also, the introduction of the dopamine can improve polyurethane’s adhesion ability ofchemical resistance. After adding different curing agents, shear adhesive strength canbe greatly improved, when compared with air oxidation curing, shear adhesivestrength increased greatest after adding of iron ion; at the same time,dopamine-containing polyurethane hot melt adhesive’ absorbing water swellingproperty has also be improved. The introduce of dopamine also can improvepolyurethane’ initial viscous force and180peel strength, while dopamine-containingpolyurethane’ PSA(pressure-sensitive adhesive) system still needs to be furtherexplored.