Synthesis of mesostructured metal sulfide films using [M(H2O)n](NO3)2:P85 (M = Cd(ii) and Zn(ii)) liquid crystalline mesophases

Abstract

Transition metal salt–pluronic liquid crystalline (TMS–PLC) mesophases of A–P85, B–P85 and ((1 − x)A + xB)–P85 (where A is [Cd(H₂O)₄](NO₃)₂, B is [Zn(H₂O)₆](NO₃)₂ and P85 is a triblock copolymer, HO(CH₂CH₂O)₂₆(CH₂(CH₃)CHO)₄₀(CH₂CH₂O)₂₆H) have been used to produce mesostructured metal sulfide films. The TMS–PLC mesophases of A–P85, B–P85 and (A + B)–P85 are well ordered with a salt/P85 mole ratio between 3.0 and 11.0 with a 3D hexagonal structure. The reaction between the mesophases of A–P85, B–P85 and ((1 − x)A + xB)-P85 and H₂S gas at room temperature produces mesostructured CdS, ZnS and Cd_1−xZn_xS films, respectively. The initial salt concentrations in the TMS–PLC phase determine the final Cd(II) and Zn(II) ions in the Cd_1−xZn_xS crystal structure, where x can be controlled between 0.0 and 1.0. Fresh samples of the mesophase reacted under an H₂S atmosphere are continues films that slowly leach out excess P85 producing P85 rich dendrite domains and aggregates of 50 to 100 nm particles of mesostructured CdS, ZnS or Cd_1−xZn_xS. However, well homogenized TMS–PLC mesophases produce stable film samples upon H₂S reaction.