Preparation And Properties Of Azobenzene-terminated Hyperbranched Polyimides

As a kind of engineering plastics,polyimides have excellent comprehensive performance,and functional polyimides have attracted the interest of the researchers and widely used in people’s lives.However,due to the rigid molecular structure and the accumulation of molecular chains,the conventional linear polyimides are hardly soluble,which limits the application of the polyimides.Therefore,it is need to design novel structure of polyimides to solve the problem.Because hyperbranched polymers have highly branched structure,they have the advantages of good dissolution properties and low solution viscosity.hyperbranched polyimides were prepared by combining hyperbranched polymer structures with polyimide materials to extend the applications of polyimides.Compared to the linear polyimides,hyperbranched polyimides have better solubility and lower melt viscosities,and a large number of terminal groups which could occur chemical reactions with functional groups.In this work,we synthesized a series of compounds containing both epoxy groups and azobenzne groups.Based on the reaction of amino-terminated hyperbranched polyimides and these compounds,a series of azobenzne-terminated hyperbranched polyamides were prepared.Then,we studied the thermal and photoresponsive properties of azobenzne-terminated hyperbranched polyimides.(1)Three kinds of compounds containing both epoxy group and azobenzne group with different structures were synthesized.Based on the reaction of amino-terminated hyperbranched polyimides and these compounds,a series of azobenzne-terminated hyperbranched polyamides were prepared.The solubility test shows that the prepared azobenzne-terminated hyperbranched polyamides had good solubility.The results of TGA test and DSC test show that all of the azobenzene-terminated hyperbranched polyimides have high glass transition temperatures and good thermal stability.In addition,we also studied the photoisomerization behavior of azobenzne-terminated hyperbranched polyimides.(2)A kind of compound containing both epoxy group and bisazobenzne group with were synthesized.Based on the reaction of amino-terminated hyperbranched polyimides and the epoxy group of the compound,a novel bisazobenzne-terminated hyperbranched polyamide was prepared.The solubility test shows that the bisazobenzne-terminated hyperbranched polyamide has good solubility.The results of TGA test and DSC test show that a bisazobenzne-terminated hyperbranched polyamide has high glass transition temperatures and good thermal stability.In addition,we also studied the photoisomerization behavior of bisazobenzne-terminated hyperbranched polyamide.