Synthesis And Morphology & Performance Of Asymmetric Particles Based On Polyvinylidene Fluoride

In this paper,the polyvinylidene fluoride@poly(styrene-co-butyl acrylate-co-3-trimethoxysilyl propyl methacrylate)composite particles,PVDF@P(St-co-BA-co-MPS),composite particles with controllable morphologies were obtained while PVDF particles was used as the seeds and the St,BA,MPS were used as the comonomers.The effects of the feeding times of MPS,the ratio of PVDF/St,the adding amount of BA comonomers,the polymerization time and the reaction temperatures on the particle morphologies were investigated in this study.The particles with popcorn-like and heteromorphous bowl-like structure can be obtained through adjusting the adding times of MPS.Additionly,a possible formation mechanism was proposed.Scanning electron microscope(SEM)and transmission electron microscope(TEM)were employed to characterize the surface morphology and internal microstructure of the composite particles.The average particle sizes and distributions of the composite particles were characterized by Malvin particle size analysis instrument.Fourier transform infrared spectrometer(FT-IR)and X-ray photoelectron spectroscopy(XPS)were used to characterize the chemical compositions of the composite particles.Further,the relationship between morphologies and crystallization behaviors of the composite particles was investigatedbydifferentialscanningcalorimetry(DSC).Andthe hydrophobicity-hydrophilicity of the composite particles was tested by the contact angle tester.The study results showed that when there was no hydrophilic monomer added,the composite particles showed a snowman-like structure.When the MPS was added at the swelling stage,the composite particles showed a popcorn-like structure.When the MPS was added after polymerization for 1 h,the composite particles showed a heteromorphous bowl-like structure.During the polymerization process,the crystallization behaviors of PVDF core particles experienced a distinct transformation from the unconfined to the confined crystallization.Whether confinement crystallization for PVDF or not largely depended on the wrapping degrees of PVDF cores.After capping the hydrophilic functional groups,the water contact angle(165 ~o)of heteromorphous bowl-like particles film became much higher than that of the popcorn-like particles film(112 ~o)due to more caves existing on the former surface,exhibiting a super-hydrophobicity.