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Functionalization of Upsalite® by aminosilane deposition from gas phase
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
2016 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

The use of desiccant materials is crucial in many applications, such as dehumidification rotors, in OLED screen and as desiccant materials in dish washers, for example. Upsalite® is a novel, anhydrous, micro-mesoporous, and large surface area structure consisting of amorphous magnesium carbonate which has been shown to exhibit a good water sorption capacity. Depending on the heat treatment of Upsalite® after synthesis, the material exhibits different sorption capacity and hydrolytic stability. Calcined Upsalite® has a higher sorption capacity compared to as-synthesized, but crystallizes into nesquehonite when stored in a relative humidity of 100 % for several days. The need to stabilize the material arises and the use of two different aminosilanes as surface stabilizers has been evaluated. Two different deposition techniques from gas phase have been used, atomic layer deposition and vapor phase grafting, which are evaluated and compared.

 

The results of the functionalization show an increase in decomposition temperature by ~25 °C of the functionalized materials compared to non-functionalized. The initial water sorption capacity of the functionalized material increases by up to 80 %, when stored in a relative humidity of 100 % for 24 h and shows a stabilizing effect after five cycles of repeated exposure to high humidity. The long term stability seems to have decreased due to pore collapse, when the functionalized material is cycled 5 times for one week in a repeated relative humidity of 100 %. The stability of the material when exposed to two liquids of different pH was also evaluated and the functionalized material exhibits a slower increase of the pH in the buffer solution, implying a retardation of Upsalite® dissolution. The conclusion is that a functionalization of the material with aminosilane increases the initial sorption capacity and has a stabilizing effect.

Place, publisher, year, edition, pages
2016. , 69 p.
Series
UPTEC Q, ISSN 1401-5773 ; 16010
Keyword [en]
Upsalite®, aminosilane, APTMS, APTS, ALD, VPG, functionalization, hydrolytic stability, XPS
National Category
Nano Technology
Identifiers
URN: urn:nbn:se:uu:diva-298135OAI: oai:DiVA.org:uu-298135DiVA: diva2:944756
Educational program
Master Programme in Materials Engineering
Supervisors
Examiners
Available from: 2016-07-05 Created: 2016-06-29 Last updated: 2016-07-05Bibliographically approved

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