Construction Of Silicone Hyperbranched Polymer Based On Piers-Rubinsztajn Reaction

This paper uses Piers–Rubinsztajn reaction to synthesize 6 new types of silicone hyperbranched polymers?Si-HBP?,using infrared spectroscopy,nuclear magnetic resonance,thermogravimetry,gel permeation chromatography,X-ray diffraction,vibrating sample magnetometer.And other characterization methods were used to characterize the synthesized Si-HBP and the precursor-converted ceramics;the product Si-HBP-3a contains organic transition metal ferrocene units,allowing the polymer to be used as a magnetic ceramic precursor,and its conversion was preliminarily studied Ferromagnetic after ceramics.The specific work is as follows:?1?Si-H functional monomers required for synthesis polymerization:1,4-dibromobenzene,4,4'-dibromobiphenyl and ferrocene are used as starting materials to synthesize the monomer 1,4-Bis?dimethylsilyl?benzene,4,4'-bis?dimethylsilyl?biphenyl,1,1-bis?dimethylsilyl?ferrocene.The structure is characterized and determined as the target product.?2?PR-reaction polymerization of Si-HBP:using three prepared three kinds of Si-H functional monomers A₂ with three different structures and methyl triethoxysilane monomer as B_3a,synthesize Si-HBP-through PR reaction 1a,Si-HBP-2a,Si-HBP-3a.Using phenyltriethoxysilane monomer as B_3b,Si-HBP-1b,Si-HBP-2b,Si-HBP-3b were synthesized.The structure of the polymer was confirmed by IR,¹H NMR,¹³C NMR and ²⁹Si NMR.The degree of branching?DB_s?of the polymers is calculated from 0.69 to 0.89,DB_Frey and DB_Fréchet from 0.55 to 0.88,indicating that these polymers have a highly branched structure.The average molecular weight of the polymer is in the range of 1850 g mol^-1 to 4300 g mol^-1,which is moderate compared with other silicon-containing HBP.The resulting polymer has a wide polydispersity index?PDI?,ranging from 2.16 to 4.21.Through TGA analysis,all polymers show high thermal stability and high decomposition temperature,Td?5%mass loss?is about 350??except Si-HBP-1a?,the yield is greater than 35%at 1000?,DSC measurements show that no polymer has a significant glass transition temperature?T_g?.?3?After Si-HBP-3a conversion,some phases in the ceramics have achieved crystal nucleation growth,combined with IR analysis to prove that the polymer has completed the conversion to inorganic substances.It was found by XRD that the product contained a large amount of amorphous element C.A certain amount of oxygen was also introduced during the firing process.The element Si exists in the form of SiO₂ and SiC,and the element Fe exists in the form of Fe₂O₃ and Fe₃O₄.The saturation magnetization of the product is 14 emu/g,the residual magnetization?Mr?and coercive force?Hc?are low,and the product has a certain ferromagnetism.The Si-HBP synthesized by PR reaction could be used as a ceramic precursor.