Copolymer-Controlled Homogeneous Precipitation for the Synthesis of Porous Microfibers of Alumina

Abstract

Mesoporous aluminas with a uniform fibrous morphology were synthesized using a copolymer-controlled homogeneous precipitation method under hydrothermal conditions. Scanning electron microscopy, X-ray diffraction, solid-state magic-angle spinning nuclear magnetic resonance, transmission electron microscopy, thermogravimetric analysis, nitrogen adsorption, Fourier transform infrared spectrometry, and elemental analysis techniques were used to characterize the samples. The effect of various synthesis conditions on the morphology and mesoporous structure of the alumina fibers was investigated. Such porous alumina microfibers may find applications in nanotechnology and catalysis. They can also be used as advanced high-temperature composite materials and templates for fabrication of fibrous materials of various compositions, such as carbon, transition-metal oxides, and polymers.

Synthesis of mesoporous alumina with tunable structural properties

“…This is attributed to their mesoporosity features such as tunable pore size, high surface area and large pore volume, which make MAs ideal for adsorption and catalysis applications [2]. MA is commonly synthesized using one of the following three methods: (1) a nanocasting method with carbon moulds as hard templates [3]; (2) solvent-deficient synthesis without structuredirecting agents (SDA) [4]; and (3) solegel self-assembly process in the presence of a soft template such as a cationic, anionic, or nonionic surfactant as SDA [1,2,5,6]. Compared to the former two, the third pathway has attracted great attention due to its easily accessible and reproducible characteristics in fabricating MA through a solvent evaporation induced self-assembly (EISA) process with a soft template under acidic conditions [7].…”

Surface-initiated ATRP of PMMA, PS and diblock PS-b-PMMA copolymers from stainless steel modified by 11-(2-bromoisobutyrate)-undecyl-1-phosphonic acid

“…to impart one or several surface properties to the final material (aspect, biocompatibility, barrier effects, chemical resistance, protection against corrosion, lubrication, molecular recognition, sensors, etc.) [1][2][3][4][5][6][7][8][9]. Durability of the coating is obviously essential and often related to the nature of the interface.…”

Tuning the structure of alumina

“…According to integration area of the two peaks, the ratio of AlO 6 and AlO 4 is approximately 2.5:1, 2.5:1 and 4:1 for MA-1, MA-5 and HMA-1, respectively. Besides, a weak signal at 35 ppm in HMA-1 sample should be assigned to five-coordination aluminum (AlO 5 ), indicating that the sample contains some amorphous domains [12]. Generally, the five-coordinated aluminum is considered as the Lewis acid center present in amorphous domains [8,28,29].…”

“…The larger pores have been demonstrated to improve the activity of mesoporous catalysts remarkably due to the decrease of diffusion resistance of reactants and products, and the smaller one can provide the active sites [2,6,10]. Our group has reported several facile ways to synthesize the alumina with mono-modal pore [11][12][13][14] and bimodal pores [2,[15][16][17][18]. However, the difference of pore structure for c-Al 2 O 3 prepared by various methods has not been systematically examined yet.…”