The Synthesis Of Polyacrylate Diol And Poly (Acrylate-acrylic) Diol By Degenerative Iodine Transfer Radical Polymerization (DITP) And Study On Their Preparation Of Waterborne Polyurethane

As the state control of VOC becomes more and more strict,the living space left for the traditional solvent-based polyurethane has become less.As a result,the market of waterborne polyurethane is getting bigger and bigger.With the elimination of solvent-based polyurethane,waterborne polyurethane has replaced solvent-based polyurethane;hence the greater need for more varieties of waterborne polyurethane.People expect to see more applications of waterborne polyurethanes.Polyacrylate is good in substrate adhesion,light stability,chemical resistance and so on.Waterborne polyurethane with polyacrylate as the soft segment and carbamate as the hard segment combines advantages of the two,obtaining waterborne polyurethane with new performances.Currently,polyacrylate-based waterborne polyurethane comes from the interaction between crosslinked systems that are physically blended,core-shell emulsions,IPN emulsions,polyurethane-polyacrylate graft and polyacrylate.However,judged from the resulting of the structure of aqueous polyurethane,it does not include the polyurethane backbone of which the main chain setting polyacrylate as the soft segment and contains a well-defined two-phase structure.It is different from the structure of polyether-based waterborne polyurethane.Changing the structure of the diol and using polyacrylate diols as macromolecular polyol can solve this problem.Used as the soft segment and reacted with the isocyanate,polyacrylate is introduced into the polyurethane backbone.The final result waterborne polyurethane would have a polyacrylate soft segment with a perfect two-phase structure of the polyacrylate-based waterborne polyurethane.On this basis,this type of polyacrylate waterborne polyurethane can be further modified by modifying polyacrylate.In this paper,n-butyl acrylate was used as a monomer and degenerative iodine transfer polymerization(DITP)method was used controllably to synthesize poly(n-butyl acrylate)diol.The polymerization process was studied by nuclear magnetic resonance(NMR),fourier transform infrared spectrometer(FTIR),gel permeation chromatography(GPC)and matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF MS).The product structure was characterized and tested.Using this poly(n-butyl acrylate)diol to synthesize waterborne polyurethane.The synthesized polyurethane structure was characterized by means of particle size and DSC.At the same time,the poly(n-butyl acrylate)diol is modified to introduce pendant carboxyl groups into the chain structure by this method,which further simplifies the feeding of the waterborne polyurethane during the synthesis and synthesize anionic waterborne polyurethanes without using dimethylolpropane acid(DMPA).The main research content is listed as follows:(1)Synthesis and characterization of poly(n-butyl acrylate)waterborne polyurethaneUsing n-butyl acrylate as the monomer;a,a-diiodo-p-xylene as chain transfer agent;toluene as solvent and decane as cosolvent;azobisisobutyronitrile(AIBN)and 4,4’-azobis(4-cyanopentanol)(ACPO)as an initiator;β-mercaptoethanol as the functional reagent to synthesize poly(n-butyl acrylate)diol.The polyacrylate-based aqueous polyurethane was synthesized by the prepolymer method using such poly(n-butyl acrylate)diol,isophorone diisocyanate(IPDI),DMPA and 1,4-butanediol(BDO)as the main raw materials.The synthesis mechanism of poly(n-butyl acrylate)diol was also studied.The structures of two polyacrylate diols were also characterized.A comparison of the particle sizes of the waterborne polyurethane dispersions synthesized with different molecular weight poly(n-butyl acrylate)diols using different initiators was also carried out.The glass transition temperature of this poly(n-butyl acrylate)aqueous polyurethane is characterized.The result shows that the synthesis of poly(n-butyl acrylate)diol complies with the mechanism of DITP.The use of ACPO can improve effectively the proportion of di-hydroxy chain to synthesize water-based polyurethane with better performances.(2)Synthesis and characterization of anionic waterborne polyurethane without hydrophilic chain extender.The poly(n-butyl acrylate)diol was introduced into the second monomer t-butyl acrylate,and the t-butyl acrylate was converted into acrylic acid by acidification to obtain polyacrylate diol that contains a certain amount of pendant carboxyl groups.Anionic waterborne polyurethane is synthesized by this diol.Similar to the above process,the structures of the macromolecular diols were characterized and the effects of n-butyl acrylate and t-butyl acrylate at different proportions on the acid value and hydroxyl value of the final diols at different reaction times were investigated.At the same time,the particle size of waterborne polyurethane synthesized in this way was compared to obtain the change of particle size due to the different proportion of acrylic acid in the macromolecular diols.