Fabrication of Pill-Shaped Polyimide Aerogel Particles Using Microfluidic Flows

Abstract

This work focuses on the fabrication and organic dye adsorption capacity of pill-shaped polyimide aerogel microparticles of diameter approximately 200 μm and length approximately 1000 μm. First, spherical polyimide sol droplets suspended in silicone oil are generated in a microfluidic droplet generator. Second, these droplets are guided into a contraction flow channel to deform them into pill-shaped droplets. Third, the pill-shaped droplets undergo sol–gel transition in a heated section of the flow channel and turn into particles. Finally, the pill-shaped aerogel microparticles are recovered via solvent exchange and supercritical drying and characterized. The data indicate that the flow rates of polyimide sol and silicone oil strongly influence the length of the microparticles while surfactants, although not necessary to obtain pill-shaped particles, exert strong influence on the aspect ratio of the particles. The aspect ratio of particles and the internal morphology are discussed using hydrodynamic and interfacial forces. The ionic dye adsorption capacity of these pill-shaped particles is determined and compared with that of spherical gel microparticles.

Macroporous Polyimide Aerogels: A Comparison between Powder Microparticles Synthesized via Wet Gel Grinding and Emulsion Processes

“…This conclusion is consistent with the observation on the N 2 isotherm plot because the wider hysteresis loop can be observed for these two samples compared to that of other samples in their groups. The reported surface area in this work (7.60–43.5 m 2 /g) shows a relatively low value compared to what was reported in the literature, which is caused by the ambient pressure drying method. , …”

“…The reported surface area in this work (7.60−43.5 m 2 /g) shows a relatively low value compared to what was reported in the literature, which is caused by the ambient pressure drying method. 46,47 The MIP for all PI-WGG and PI-EM samples represents the pores in the range of 2−250 μm and bimodal distributions, indicating that the pores are mostly mesopores and macropores. A narrow peak can be observed for all conditions and inter-and intrapore distributions.…”

Meso- and Macroporous Polymer Gels for Efficient Adsorption of Block Copolymer Surfactants

“…Extensive work shows that pore size 22,23,27 and wettability 28 can be tuned, and the gels can be fabricated into various shapes and sizes 29−31 to suit the desired applications of aerogels, such as thermal insulation, 32 air filtration, 20,33 and dye removal from wastewater streams. 29 The three polymer gels used in this work are sPS, PI, and PUA. All three gels offer high porosity with hierarchical porous structures composed of meso-and macropores.…”

“…The corresponding aerogels obtained by supercritical drying of the gels provide a high surface area (250–800 m 2 /g) and high porosity (>90%). Extensive work shows that pore size ,, and wettability can be tuned, and the gels can be fabricated into various shapes and sizes − to suit the desired applications of aerogels, such as thermal insulation, air filtration, , and dye removal from wastewater streams …”

Palladium nanoparticles encapsulated in polyimide nanofibers: An efficient and recyclable catalyst for coupling reaction

“…[12][13][14] Among various polymers, polyimides (PI) are well known for their superior thermal property and chemical resistance as well as mechanical properties. [15,16] PI nanofibers based on pyromellitic dianhydride (PMDA) and 4,4 0 -oxidianiline (ODA) have been prepared by electrospinning the precursor of polyimide, a poly(amic acid) (PAA) solution, with subsequent thermal imidization. The prepared PI nanofibers hold many attractive applications.…”