Paper TF-TuA3
Synthesis of Micro/Mesoporous Alumina Fibers by Gas Phase Infiltration of Polyesters with Trimethyl Aluminum and Water

Tuesday, October 19, 2010, 2:40 pm, Room Ruidoso

Preparation of inorganic micro/mesoporous materials has attracted considerable attention because of their function in catalytic, separations, and other applications. Although many approaches are known to synthesize porous materials, methods to form mesoporous materials with pre-determined shape and morphology are not readily known. Sub-surface deposition, recently observed during atomic layer deposition (ALD) on polymer substrates, provides a potential method to transform polymers from fully organic solids into organic-inorganic hybrid and micro/mesoporous materials. Moreover, the transformation allows polymers with well defined micro and nano-structure, such as polymer fiber matrices, to maintain their shape and structure to form new replica materials. In this presented work, we apply this process to synthesis of Al-O/organic hybrid micro fibers by gas phase infiltration of tri-methyl aluminum and water alternatively into polyesters, such as polybutylene terephthalate (PBT). Through in-situ infrared analysis, we show that TMA acts as a strong Lewis acid and attacks the nucleophilic ester groups in polyesters to insert Al-O bonds into the polymer chains. The organic components are removed by post annealing to produce a micro/mesoporous alumina fiber. Surface area, pore volume, and pore size distribution of the porous alumina fibers were tested by nitrogen adsorption/desorption experiments, and surface areas exceeding 400 m²/g were obtained. SEM was used to track the morphology change along the process, and cross-section TEM images of annealed samples confirmed the formation of porous structures.