Study On Preparation And Film Properties Of The Vanillin-based Polyurethane

Polyurethane(PU)has been widely used in the coatings industry owning to excellent physical,chemical,mechanical and thermal properties.Generally speaking,polyurethane is mainly prepared from petroleum-based raw materials.However,many scientific and industrial studies have successfully reported using renewable raw materials for the preparation of polyurethanes.The main research in this area was the vegetable oil-based polyol synthesis.Although vegetable oil has been widely studied in polyurethane,but the shortcoming of poor mechanical properties of vegetable oil-based polyurethane was salent.To overcome this problem,at present,scientists are turning to study with the aromatic ring of the renewable resources used in the field of polymers.Vanillin,with feature of widely available and inexpensive,the molecular structure of vanillin contains a phenolic hydroxyl group and aldehyde,which can be modified by organic synthesis methods to prepare various of vanillin-based polymerizable monomer and vanillin-based polymer.In this paper,vanillin was used as starting material for the preparation of vanillin-based polyurethane,mainly in the following aspects of the work and research:1.Preparation and properties of vanillin-based UV curing polyurethaneVanillin-based diol contains a carbon-carbon double bond was synthesized using cheap and readily available renewable resources vanillin as a starting material,the structure was characterized by infrared spectrometer(FT-IR)and nuclear magnetic resonance(NMR).Then vanillin-based linear polyurethane with side chain of double bond was prepared using unsaturated vanillin-based diol,polyether N210,isophorone diisocyanate(IPDI)and 1,4-butanediol as materials.Four thiol compounds were used as UV curing agent for the preparation of vanillin-based polyurethane.Thermal properties of vanillin-based polyurethane were studied with dynamic mechanical analyzer(DMA),differential scanning calorimetry(DSC),thermo gravimetric analyzer(TGA).The results showed that vanillin-based polyurethane was successfully prepared,and the structure of curing agent has an important influence on the final properties of the vanillin-based polyurethane.Vanillin-based polyurethane using polyfunctional and moderate chain length trimethylolpropane(3-mercaptopropionate)(3T)as curing agent,which obtained good stress strain,highier initial degradation temperature,water absorption of 2.2% and pendulum hardness of 4.2s.2.Preparation and properties of fluorine and silicon functionalized vanillin-based polyurethaneFluorine and silicon functioned vanillin-based polyurethane were prepared via mercapto terminated fluoride(HFBASH)and mercaptopropyl trimethoxysilane modified vanillin-based polyurethanes respectively.The structure and properties of fluorine and silicon functionalized vanillin-based polyurethane were charactered by FTIR,sol-gel permeation chromatography(GPC),TGA,etc.From the FTIR spectra,the mercapto n the fluorine and silicon functionalized vanillin-based polyurethane cannot be observed as well as double peaks are weakened,fluorine and silicon absorption peaks obviously proved in fluorine and silicon functionalized vanillin-based polyurethane,which confirmed that HFBASH and mercaptopropyl trimethoxysilane occured thiol-ene click reaction with vanillin-based linear polyurethane with side chain of double bond linear polyurethane.GPC results showed that the molecular weight of the vanillin-based linear polyurethane with side chain of double bond linear polyurethane increased after functioned with fluorine and silicon.TGA results showed that increasing thermal stability compared with previous polyurethane without functionalization.DSC datas showed a slight increase in glass transition temperature of the functionalized polyurethanes.From the water contact angle datas,an increasing in the contact angle of fluorine and silicon functionalized vanillin-based polyurethane even at a lower fluorine or silicon element content.In addition,water absorption decreased and pendulum hardness increases in the polyurethane after functionalization.3.Fatty acids modified vanillin-based diol and preparation of vanillin-based polyurethaneVanillin modified eleven acid-based diol and oleic acid-based diol were prepared by thiol-ene click chemistry.Eleven acid-based diol without aromatic was designed and prepared at the same time for performance comparison.Three linear polyurethanes were prepared using above three fatty acid-based diols to copolymerization with IPDI.Generating of polyurethane structure was confirmed by FTIR,molecular weight of polyurethane was measured by GPC,thermal performance was evaluated by TGA.Results showed that fatty acid modified vanillin-based polyurethane exhibit superior thermal stability and mechanical properties,with initial degradation temperature higher than 261 ?.Wherein,undecylenate modified vanillin-based polyurethane with water absorption of only 0.5% and pendulumhardness up to 22.4s.