The Application Of Amiphiphilic Block Copolymers P(St)-b-P (HEA) In The Preparation Of Al₂O₃ Powder

Ultrafine alumina powder, especially ultrafine α-Al₂O₃ powder is an important material for applications such as catalyst supports, fine ceramics and composite materials. Although numerous techniques have been developed for the preparation of alumina powders, it is still a challenging task with high value for the fabrication of ultrafine alumina powder with different morphologies. In this article, we attempt to prepare alumina with different morphologies by precipitation and hydrothermal methods in the presence of amiphiphilic block copolymers of P(St)-b-P(HEA).Firstly, by using Ethyl 2-bromoisobutyrate(EbiB) as the initiator, CuBr as catalyst and bpy as the ligand, the amiphiphilic block copolymers of P(St)-b-P(HEA) have been synthesized by atom transfer radical polymerization(ATRP) and characterized by FT-IR,GPC and TG/DTG . Its micellization in mixed solvent have been observed by TEM.Secondly , by using proper kind and use level of P(St)-b-P(HEA) as dispersing agent, Al(OH)₃ gel was prepared by using Al₂(SO4)₃ and NH₃·H₂O solutions as raw materials. XRD analysis showed that α-Al₂O₃ nano-crystalline powders were prepared by calcining the gel at 800 ℃ for 1.5 h .The morphology of α-Al₂O₃ powders were minitored by TEM and SEM .By using Al₂(SO4)₃ and different use level of urea as raw materials, γ-A100H aggregations with different morphologies, such as splintershaped, spherical, whiskers, coral-shape and peanut-like, were prepared in the presence of P(St)-b-P(HEA) under hydrothermal condition. After calcining at different temperature, γ-Al₂O₃ or α-Al₂O₃ powder with different morphologies were prepared. XRD was used to confirm the relationship between crystalline form and calcining temperature.The effection of the use level and kind of P(St)-b-P(HEA) and the use level of urea on the morphology of γ-AlOOH and Al₂O₃ was studied by TEM and SEM.