Study On Preparation And Properties Of Waterborne Polyurethane Modified By Perylene Tetracarboxylic Dianhydride And Its Derivatives

Water-based polyurethane(WPU)uses water as a solvent and has the advantages of environmental protection,low temperature resistance,and good adhesion.It is widely used in leather finishing,environmental protection coatings,adhesives and textiles.Waterborne polyurethane has the advantage of adjustable soft-hard segment structure.By designing different molecular structures,functional materials with recyclable,self-healing and shape memory properties can be prepared.In this paper,1,7-dibromo-3,4,9,10-perylenetetracarboxylic dianhydride(PBI)derivatives are used to modify the soft segment structure of WPU to synthesize a series of linear and cross-linked waterborne polyurethanes.And its mechanical properties,recyclable properties,shape memory properties and water resistance properties have been studied.The main work is as follows:(1)Synthesis and performance research of linear waterborne polyurethane based on PBI modified soft segment.First,two dihydroxy perylene imides(PBI-OH and PBI-PIP-OH)were synthesized using PBI,ethanolamine and piperidine(PIP)as the main raw materials.Then,PBI modified polycaprolactone diols(PBI-PCL and PBI-PIP-PCL)were synthesized through ring-opening polymerization,and finally PBI-PCL/Polytetrahydrofuran ether glycol(PTMG)and PBI-PIP-PCL/PTMG were used as mixed soft segments,isophorone diisocyanate(IPDI),sodium ethylenediaminoethanesulfonate(A95)and 2,2-dihydroxymethylpropionic acid(DMPA)are hard segments,and a series of linear waterborne polyurethanes(PWPU and PPWPU)have been prepared.Using 1,4-butanediol(BDO)modified polycaprolactone diol(BDO-PCL)/PTMG as the mixed soft segment,IPDI,A95 and DMPA are hard segment,and a series of experimental control linear waterborne polyurethanes(BWPU)have been prepared.In this paper,the effects of different soft segment structures,molecular weights of PBI-modified polycaprolactones and addition amounts on the performance of linear waterborne polyurethanes were investigated.The results of thermogravimetric analysis(TGA)and mechanical tensile test showed that the thermal stability and mechanical properties of PWPU and PPWPU films were significantly improved with the addition of PBI-PCL and PBI-PIP-PCL.The results of atomic force microscopy(AFM)and dynamic thermomechanical analysis(DMA)showed that the PWPU film has a more regular microphase separation structure,therefore,the addition of PBI-PCL has a positive effect on the shape memory function of PWPU films;In this paper,an environment-friendly recycling process of WPU was developed,which realized the green recycling of "WPU emulsion-WPU film-WPU emulsion".After three times of recycling,the thermal stability of PWPU film remained unchanged,and the mechanical properties kept 88.6% of the initial mechanical properties.However,BWPU and PPWPU films are not recyclable,which indicates that the different soft segment structure leads to the different recyclable properties of polyurethane.The new recycling process has been successfully applied to the separation and recovery of PWPU coating and synthetic leather base,which has broad application prospects in the recycling of synthetic leather composite materials.The above research shows that the mechanical properties,thermal stability,shape memory performance and recyclability of linear waterborne polyurethane film are significantly improved by introducing PBI-PCL rigid chain into soft segment.(2)Synthesis and performance research of cross-linked waterborne polyurethane based on PBI modified soft segment.Two tetrahydroxy perylene imides PBI-(OH)4and PBI-PIP-(OH)4 were synthesized using PBI,serinol and piperidine(PIP)as the main raw materials,and then synthesized by ring-opening polymerization PBI modified four-arm polycaprolactone PBI-(PCL)4 and PBI-PIP-(PCL)4,finally,PBI-(PCL)4/PTMG and PBI-PIP-(PCL)4/PTMG are mixed soft segments,IPDI,DMPA,A95 as the hard segment,a series of cross-linked waterborne polyurethanes(PWPU4-x and PPWPU4-x)have been prepared.In this paper,the influence of the structure of different soft segments and the content of PBI modified four-arm polycaprolactone on the properties of cross-linked waterborne polyurethane was studied.The emulsion performance test results show that the particle size of the cross-linked waterborne polyurethane emulsion is larger than that of the linear waterborne polyurethane emulsion.The particle size of the emulsion increases with the increase of the degree of crosslinking,and the stability of the emulsion tends to decrease;The fluorescence spectrum(FL)spectrum shows that the maximum emission wavelength of PWPU4-x is550 nm,the maximum emission wavelength of PPWPU4-0.4 emulsion is 770 nm,and the maximum emission wavelength of PPWPU4-1.6 reaches 820 nm.With the increase of PBI-PIP-(PCL)4,the maximum emission wavelength is red-shifted by 50 nm.AFM confirmed that PWPU4-x and PPWPU4-x have a certain microphase separation structure,which gives the cross-linked polyurethane a shape memory performance.Tensile strength of PWPU4-1.6 film containing 1.6 mmol PBI-(PCL)4 can reach 73.6 MPa,and that of PPWPU4-0.8 film containing 0.8 mmol PBI-PIP-(PCL)4 can reach 61.92 MPa,proper crosslinking is beneficial to improve mechanical properties.Proper cross-linking resulted in a gradual increase of the water contact angle of the polyurethane films up to 117°,exhibiting hydrophobicity.The difference in the soft segment structure resulted in better mechanical properties,thermal stability and water resistance of PWPU4-x films than PPWPU4-x films under the same formulation.Compared with linear waterborne polyurethanes of the same molecular weight polycaprolactone and the same formulation,the cross-linked waterborne polyurethanes showed significant improvements in mechanical properties,thermal stability and water resistance.