Preparation And Application Of Polyamine Functionalized Acrylic Fiber With Adjustable Polarity

As a new carrier,fibrous materials have been widely used in the preparation of functional materials due to their low cost and large specific surface area and easy recovery.Acrylic fiber is a kind of fiber material with low price,large specific surface area,easy recovery and a large number of active groups.Therefore,functional acrylic fiber can be used in the fields of catalysis,adsorption and detection.High adsorption performance is the key to improve the performance of functional acrylic fibers in many applications.In this paper,polyacrylonitrile fibers with high adsorptive capacity and controllable polarity were prepared by amination and quaternization,and were used in dye adsorption and phase transfer catalysis.The adsorption and phase transfer catalytic capacity of the fibers were investigated by changing the loading amount,the length of supported carbon chain and introducing benzyl group near the amine functional group to regulate the surface polarity of the fibers.The main research contents and conclusions are as follows:(1)Preparation of polyamine functionalized acrylic fiber.Different tertiary amination fibers were prepared by one-step amination and two-step amination methods.The effect of reaction temperature and time on the modification degree of tertiary amination was investigated.The quaternary amination fibers were obtained by further reaction of the tertiary amination fibers with halogenated hydrocarbon.The results show that the modification degree of tertiary amination increases with the increase of time and temperature.When the reaction temperature is90? and the reaction time is 5 h,the modification degree of tertiary amination is the highest,and it will not cause serious damage to the fiber.Due to steric hindrance,the length of carbon chain of the tertiary amine modifier affects the quaternary amine,and the quaternary amine conversion rate of diethyl amine(50%)is less than that of dimethyl amine(93-96%).FTIR and XPS confirmed the successful preparation of polyamine functionalized fibers.And SEM showed that the morphology and structure of the modified fibers had no significant change.Tertiary amination modification and quaternary amination modification could improve the hydrophilicity effect,and the longer carbon chain l and the introduction of benzyl group nearby will reduce the hydrophilicity.(2)Application of polyamine functionalized acrylic fiber in adsorbing dyes.Taking the phase transfer catalytic reaction of p-methylphenol and p-nitrobenzyl bromide as an example,the catalytic performance was analyzed,and the effects of modification degree,functional group type,carbon chain length and benzyl group on the catalytic activity were studied.The adsorption kinetics,isothermal equation and adsorption mechanism were studied.The results show that the higher the modification degree,the more adsorption sites,the better the adsorption capacity;The adsorption sites with longer carbon chains and benzyl groups can reduce the surface polarity of the fibers and improve the adsorption capacity;The adsorption capacity of quaternary aminated acrylic fiber is better than that of tertiary aminated acrylic fiber under neutral and alkaline conditions,and the maximum adsorption capacity is 1652 mg / g;Under the condition of acid,the tertiary aminated acrylic fiber has better adsorption effect,and the maximum adsorption capacity is 2053.7 mg/g,and the adsorption rate was 73% of the first time after 8 times of desorption adsorption repetition,which showed good reuse.The kinetic and isothermal adsorption experiments showed that the dye adsorption on the modified fiber was mainly due to the formation of ionic bond,supplemented by van der Waals force and hydrogen bond.During the adsorption,the dye first diffused rapidly from the diffusion layer of the fiber to the adsorption layer,and then slowly diffused into the fiber.(3)Application of polyamine functionalized acrylic fiber in phase transfer catalytic reaction.The effects of fiber surface polarity and adsorption capacity on Williamson's etherification reaction were studied.The results show that the quaternary aminated acrylic fiber has better catalytic ability,and with the increase of modification degree,the catalytic activity increases first and then remains unchanged.The increase of the length of carbon chain in quaternary amine group and the introduction of benzyl group could accelerate the transport of phenol anions in the fiber,thus increasing the catalytic activity.However,the hydrophilicity of the fiber will decrease and the catalytic activity will decrease if the fiber is modified with more aniline.The highest catalytic activity could be obtained when the modified weight gain of benzylamine is 24%,the modified weight gain of diethyltertiary amine is 33%,and the modified weight gain of quaternary amine is 15%,which had good catalytic effect when it was recycled for 8 times.When the fiber catalyzes the phase transfer reaction,the cation center adsorbs the anions in the aqueous phase,and the change of the fiber polarity has a certain lipophilicity,so that the negative ions can enter the organic phase to complete the reaction.However,the appropriate hydrophilicity and hydrophobicity of the fiber surface is the key to coordinate the polarity change.