Investigations on polyaniline–TiO[sub 2] nano-composite Langmuir Blodgett thin films

Bhullar, Gurpreet Kaur; Kaur, Ramneek; Raina, K. K.

doi:10.1063/1.4810315

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“…This instability has been overcome by modifying the TiO 2 particles by surfactants or polymers to make them hydrophobic, and then by spreading these hydrophobized particles on an air/aqueous interface. 10,11 Nonmodified hydrophilic TiO 2 particles have also been made stable at an air/aqueous interface by changing the subphase from pure water to one of low pH. 12 The disadvantage of using the indirect method to form a monolayer of TiO 2 particles from a colloidal TiO 2 subphase is that a strong interaction is required between the particles in the subphase and the surfactant or polymer molecules in the monolayer at the air/aqueous interface.…”

Section: Introductionmentioning

confidence: 99%

Formation of Langmuir Monolayers of Titanium Dioxide Nanoparticles at Air/Aqueous Interfaces by the Addition of Ions to the Subphase: Effect of Ion Concentration and Type

Iwafuji

McNamee

2015

J. Phys. Chem. B

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A Langmuir monolayer of bare, hydrophilic TiO2 nanoparticles (diameter = 75 nm) was formed at an air/pH 5.8 aqueous interface by adding salt to the subphase. The effect of the concentration and type of salt in the subphase on the surface pressure-area per particle isotherms was determined. Increasing the concentration of NaCl from 0 to 3.8 M increased the maximum surface pressure (Πmax) and shifted the isotherms to a larger area per particle. The ion type also affected the area at which the close packing commenced and the value of Πmax. The presence of salt in the subphase also stabilized SiO2 nanoparticles, suggesting that the ions in the subphase interacted with the dioxide groups on the particles. The combination of structure making or borderline ions with structure breaking ions (LiCl, MgCl2, NaCl, and CaCl2) appeared to stabilize the particulate monolayers more than the combination of structure breaking ions (KBr and KCl). These results suggested that the particles were stabilized by a hydrogen bond network between the particles or the formation of a salt bridge between the particles. Attractions between particles at the air/aqueous interface caused the particles to aggregate, resulting in the particles becoming more stable at the air/aqueous interface.

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Section: Introductionmentioning

confidence: 99%