Research On Covalent Adaptable Networks And Perfermance Based On Aceylate Emulsion Polymer

Covalent adaptable networks(CANs)refer to polymer networks with dynamic and exchangeable covalent bonds embedded in the cross-linked structure.The construction of CANs retains the excellent properties of thermosetting materials while giving the polymer the characteristics of repair,recycling and reprocessing.This helps to prolong the service life of the material and solve the problems of environmental pollution and resource waste caused by the non-recyclable thermosetting polymer.Acrylic resin products are widely used in plastics,adhesives,fibers,coatings,elastomers and other fields,so it is necessary for the construction of CANs.For the environmentally friendly waterborne acrylate emulsion prepared by emulsion polymerization as the main synthesis method,the emulsion polymerization itself has strong random polymerization characteristics,and it must also take into account the stability and compatibility of the polymer colloid,which above limits the types of dynamic bonds and the molecular structure design of copolymers.In this thesis,based on the ketoamine reaction,through a simple and easy process,a covalent adaptable acrylate networks with dynamic groups of disulfide and vinylogous urethanes were prepared,and the repair performance,thermal remodeling,and rheology and other properties were deeply explored.The research content is as follows:1.Through the solvent medium,the synthesized 4,4'-diaminophenyl disulfide(DTDA)was introduced into the acetoacetoxy functionalized coreshell acrylate latex(AAEm-latex)and then cured into a cross-linked AAEmDTDA latex film containing disulfide bonds.The stress relaxation activation energy of 73 kJ/mol shows the dynamic nature of the polymer network,and the creep experiment shows that the static crosslinking of the core layer is beneficial to the creep resistance.The influence of AAEm-DTDA dosage,monomer feeding method and composition on the mechanical properties and self-healing properties of the material was systematically studied.The optimized sample 5%AAEm-DTDA latex film with the ? of 15.8 MPa and ? of 245%self-healed from the cut-off damage at 80? under the pressure of 1 MPa for 1 h,exhibiting the ?? of 93.4%and ?? of 98.5%.Furthermore,the cured film can be recycled through the fragmentation-hot-pressing process under relatively mild conditions,and repair efficiency obtained after three reprocessing cycles was maintained at?75%or more.2.The molecular weight regulator AMSD was used to adjust the molecular weight,and the non-core-shell AAEm-DTDA latex was synthesized by the uniform monomer feeding protocol,and the color paint was prepared by compounding with pigments and fillers.Varnish and colored paint films have good apparent hardness and substrate adhesion,and had obvious self-repair effect on surface scratches at a temperature of 100?.The above expands the application of dynamic crosslinking in the field of commercial resins.3.Acrylate latex containing acetoacetoxy functional groups was postcured by tris(2-aminoethyl)amine(TREN).vinylogous urethanes covalent adaptable acrylate network of acrylate can directly be prepared after blending and casting into a film.The calculated stress relaxation activation energy is 105 kJ/mol and a typical dynamic crosslinking creep curve was shown.The mechanical properties of 10%AAEm-TREN could still reach the original tensile strength of 23.8 MPa after 4 reprocessing cycles.The design Tg of the emulsion polymer has little effect on the recovery of tensile properties.The results of DMA,infrared and gel content all show that the original dynamic crosslinking network is retained after the reprocessing cycle.