Preparation And Properties Of Fluorescent Waterborne Polyurethane Materials

Based on the expectation of building an environment-friendly society and the further requirements of various laws and regulations,people’s awareness of environmental protection has been enhanced gradually,which requires not only the superior performance of polymer materials,but also whether they meet the expectation of environment-friendly.Water-based polyurethane(WPU)is a kind of polymer material with water as the dispersion medium,which can still maintain excellent performance and low cost while meeting the requirements of environmental protection,so it is concerned in the industry.Fluorescent materials are the focus of current research,which have been widely used in various fields.The waterborne polyurethane fluorescent material is prepared with polyurethane as the carrier of fluorescent material which can achieve more excellent optical properties and applications.In this work,due to the performance advantages of waterborne polyurethane materials,small molecule fluorescence is synthesized,which is introduced into waterborne polyurethane to prepare waterborne polyurethane fluorescent materials and its properties are explored.In the second chapter,a double hydroxyl Schiff base fluorescent compound(SBF)was prepared by the simple one-step reaction of benzyl two amine and 4-(two glycolylamino)salicylaldehyde.Isophorone diisocyanate(IPDI)and polyoxypropylene glycol(PPG)were used as raw materials,and introducing SBF into WPU,the fluorescent WPU emulsion was prepared.The structure of SBF was characterized by 1HNMR and FTIR.The analysis of the emulsion state showed that the stability of the WPU emulsion prepared by adding SBF to the chain extension process is good.The results of optical property test showed that the fluorescent molecules SBF and fluorescent WPU all had bright blue light under the 365 nm ultraviolet lamp,the UV absorption peak of the fluorescent molecules appeared at 420 nm.The fluorescence spectrum test shows that the fluorescence intensity of WPU is higher than that of SBF at the same concentration,which indicates that the idea of WPU as the matrix of fluorescence molecules to enhance fluorescence is feasible.In the third chapter,with IPDI as the hard segment and PPG as the soft segment,a series of FWPU emulsions with different fluorescence content were prepared by adding differentmass fraction of SBF into the chain extension process.The structure of FWPU was characterized by IR spectrum.The particle size distribution and emulsion state of FWPU were analyzed.The results showed that with the increase of the mass fraction of SBF,the particle size increased and the storage stability of the emulsion decreased.The thermogravimetric analysis showed that:when the fluorescence content of SBF increased to a certain extent,the initial degradation temperature decreased significantly.The mechanical properties test showed that the effect of fluorescence content on the mechanical properties of the film was first enhanced and then weakened.When the fluorescence content increased to 0.075%,the tensile strength of the film increased to 38.6MPa,and the elongation at break also increased to574%.With the increase of fluorescence content,the mechanical properties began to decrease.The UV spectrum test showed that the UV absorption peak of FWPU appeared at 335 nm,and the UV absorption intensity also enhanced with the increasing of SBF content,the fluorescence intensity increased first and then decreased with the increasing of concentration.The fluorescence intensity reached the maximum when the SBF mass fraction was 0.05%.The fluorescence lifetime and quantum yield of FWPU with different concentrations are higher than that of SBF with pure concentrations,when the concentration reached a certain level,the fluorescence quantum yield of FWPU gradually decreased with the increasing of concentration.In the fourth chapter,different kinds of isocyanates were used as hard segments,PPG as soft segments,SBF was added in the chain extension process,and a series of HWPU emulsions were prepared by designing different hard segment contents.The structure of HWPU was characterized by FTIR spectrum.The particle size distribution and emulsion state showed that the emulsion particle size increased with the increasing of hard segment content,and the stability of HWPU emulsion with lipidocyclic isocyanate as hard segment is best.The optical performance test came to the conclusion that with the increase of hard segment content,the absorption intensity of UV increases,and the fluorescence intensity shows the same increasing trend.Under the same fluorescence concentration,HMDI shows better fluorescence performance than IPDI,and the HWPU made of hard segment HMDI shows better fluorescence lifetime and quantum yield than that made of IPDI.In the fifth chapter,a series of fluorescent LWPU emulsions were prepared withpolytetrahydrofuran glycol(PTMG)and polycarbonate diol(PC)as soft segments and HMDI as hard segments and the structure of LWPU were characterized by FTIR.The particle size test and emulsion state showed that a series of LWPU emulsions with uniform particle size distribution and excellent emulsion storage properties were prepared.It can be seen from the contact angle and SEM test that the surface of LWPU film is relatively flat.With the increasing proportion of PC soft segment,the contact angle of the film increases,showing better hydrophobicity,but the change of water absorption of LWPU film has no obvious rule.The mechanical property test shows that with the increasing of PC soft section proportion,the elongation at break of LWPU film were decreased gradually,the tensile strength were enhanced step by step,and the 100% modulus presented a decreasing trend,the 100%modulus of LWPU-5 reaches the minimum value of 2.16 MPa.The LWPU film emits bright blue light under 365 nm UV light.The fluorescent performance test results show that the fluorescence emission intensity of LWPU film increased first and then decreased under different tensile strains.The fluorescence peak strength increased when the tensile strain was less than 100%,but decreased when the tensile strain was higher than 100%.The fluorescence performance of LWPU film was sensitive to temperature,with the increasing of system test temperature,the fluorescence intensity of the film decreased gradually.This kind of film is expected to be a kind of fluorescent surface synthetic leather material.