| In this paper,two kinds of complex colloidal polymeric particles and their waterborne coatings were successfully synthesized following the traditional free radical polymerization mechanism via seeded emulsion polymerization.In the first system,poly(vinylidene chloride)(PVDC)seed latex was first synthesized by emulsion polymerization of vinylidene chloride(VDC)monomers,subsequently the core-shell structure of PVDC/P(CTFE-co-MMA-co-BA)(PVDC/PCMB)particles were prepared via seeded emulsion copolymerization of PVDC seed particles with chlorotrifluoroethylene(CTFE),methyl methacrylate(MMA),and butyl acrylate(BA)comonomers.In the second system,P(VDC-co-BA)(PVB)seed latex was first synthesized by emulsion polymerization of VDC and BA comonomers,subsequently the core-shell structure of PVB/P(CTFE-co-IBVE)(PVB/PCI)particles were prepared via seeded emulsion copolymerization of PVB seed particles with CTFE and isobutyl vinyl ether(IBVE)comonomers.The latexes containing VDC copolymer composite particles could be further used to produce a multifunctional water-based coating with environmentally friendly characteristic.The effects of the comonomer composition ratio of core or shell layer and the mass ratio of shell/seed on the film-forming,adhesion,surface wettability,corrosion resistance and weather resistance of waterborne coatings were studied.The effects of the microstructure and chemical composition of VDC copolymer composite particles on the macroscopical properties of the products were summarized.The particle size distribution,micromorphology,element distribution,internal structure,chemical component,and crystallization behavior were analyzed by dynamic light scattering(DLS),scanning electron microscopy(SEM),energy-dispersive X-ray spectroscopy(EDX),transmission electron microscopy(TEM),fourier transform infrared spectrometer(FTIR)and X-ray powder diffractometer(XRD),respectively.The multi-layer microstructure and complex chemistry composition of the composite particles were characterized and analyzed.Electrochemical impedance spectroscopy(EIS)was used to test the anticorrosion performance of waterborne coatings prepared from VDC copolymer composite particles.The adhesion of the coating was evaluated by the grid method.The weather resistance of the coating was detected by ultraviolet aging tester and gloss meter.The research results for the two systems demonstrated that comonomer composition ratio and core-shell mass ratio were keys to controlling the microstructure of composite particles and macro-properties of coatings.In the PVDC/PCMB coating system,when the MMA/BA composition ratio was 2.50g/2.50g,and the PVDC seed/PCMB shell mass ratio was 2.50g/15.00g,the PVDC/PCMB latex could easily form a coating at room temperature within 8h as well as maintain a strong adhesion to the tinplate substrate(5B).In addition,PVDC/PCMB coating showed the outstanding corrosion resistance even after immersion in 3.5wt% NaCl solution for 400h.In the PVB/PCI waterborne system,when the composition ratio of VDC/BA was 20.00g/2.00g and the mass ratio of PVB seed/PCI shell monomer was 3.60g/13.98g,PVB/PCI composite coating still had no gloss loss even after repeated high-intensity ultraviolet(UV)irradiation,displaying excellent weather resistance.As a result,the waterborne coating prepared by VDC copolymer composite particles could achieve the comprehensive regulation of film forming performance,weatherability,anticorrosion performance and adhesion performance due to its multi-layer structure and specific chemical composition,which will pave the way for potential industrial applications of multi-functional waterborne coatings. |
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