Amine Functionalization of Silica Sol–Gel Thin Films via Kinetic Doping: A Novel, Green Approach

Abstract

Amine-functionalized thin films are highly desirable technologies for analytical, material, and biochemistry applications. Current functionalization procedures can be costly, environmentally unfriendly, and require many synthetic steps. Here, we present an inexpensive and facile way to functionalize a silica thin film with a 25 000 MW branched polyethylenimine (BPEI), consistent with green chemistry principles. Using UV–vis spectroscopy and scanning electron microscopy, BPEI was determined to be loaded into the film at an approximately 0.5 M concentration, which is a 500× increase from the loading solution used. The films were also tested for copper(II) sequestration to assess their potential for heavy metal sequestration and showed a high loading capacity of 10 ± 6 mmol/g. Films proved to be reusable, using ethylenediaminetetraacetic acid to chelate copper and regenerate the films, with only a 6% reduction in the amount of copper(II) ions sequestered by the third use. The films also proved stable against leaching over the course of 1 week in solution, with less than 1% of the original BPEI lost under various storage conditions (i.e., storage in deionized (DI) water, storage in dilute BPEI solution, storage in DI water after annealing). These films show promise for multiple applications, from heavy metal sequestration to antifouling applications, while being inexpensive, facile, and environmentally friendly to synthesize. To our knowledge, this is the first time that BPEI has been doped into silica thin films.

Enzyme Loading in Internally-Coated Capillary Tubes Via Kinetic Doping

“…Flat coverslips (25 mm × 25 mm × 170 µm) were suspended above a beaker atop a jack stand containing the sol solution, and the jack stand was raised until the coverslip was completely submerged. The sol was drained at the same rate, and coverslips were placed directly in loading solutions after a 5 min delay time [34].…”

Additives enhancing supported amines performance in CO2 capture from air

“…5 The use of adsorbents plays a crucial role in DAC and has sparked a surge of new ideas for developing new materials in the past 5 years. 6,7 Amine-functionalized porous materials, including zeolites, 8,9 activated carbon, 10,11 mesoporous silica, 12,13 metal-organic frameworks, 14,15 and silica sol-gel, 16,17 are widely studied due to their high affinity toward CO 2 , [18][19][20][21] low energy cost, and robust stability even in the presence of moisture. 22 They effectively address the deficiencies of amine solution absorption and interact with CO 2 in a chemisorptive manner, [23][24][25][26][27] resulting in relatively high adsorption heat and steep adsorption isotherms, 28 which have been proved to the benefit of significant CO 2 capacity under air conditions.…”