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Size and Microstructure Control of Calcium Aluminate Microcapsules
Author(s) -
Sturzenegger Philip N.,
Gonzenbach Urs T.,
Martynczuk Julia,
Gauckler Ludwig J.
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05191.x
Subject(s) - aluminate , anhydrous , cement , chemical engineering , microstructure , particle size , suspension (topology) , materials science , calcium , mineralogy , yield (engineering) , hydrate , capsule , particle size distribution , particle (ecology) , chemistry , composite material , metallurgy , organic chemistry , botany , mathematics , oceanography , homotopy , pure mathematics , engineering , biology , geology
Microencapsulation is nowadays widely applied for the separation or controlled and targeted release of substances. In the present work we propose using particle‐stabilized water‐in‐oil emulsions to produce microcapsules from calcium aluminate cement. First, we investigate the parameters determining the capsule size and size distribution. Then, the anhydrous particles at the water‐oil contact line are hydrated resulting in the formation of a layer of precipitated calcium aluminate hydrate that strengthens the capsule shells. By manipulating the hydration reaction of the cement particles, the capsule shell thickness is varied between 200 and 1300 nm. For hydration temperatures of 3°C and 25°C, the capsule walls are mainly formed from Ca 2 Al 2 O 5 ·8 H 2 O , whereas Ca 2 Al 2 O 5 ·8 H 2 O and the stable γ‐ Al ( OH ) 3 and Ca 3 Al 2 O 6 ·6 H 2 O phases are precipitated at 60°C. In addition, the impact of these manipulations on the yield of dry microcapsules is discussed. The highest yield of intact capsules observed in this study is 72 ± 3%. We believe that such microcapsules can lead to new applications, particularly in environments with harsh conditions or in inorganic matrixes.