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  • Effects of hydrogen bonding on the monolayer properties of amphiphilic double-decker-shaped polyhedral silsesquioxanes.

Effects of hydrogen bonding on the monolayer properties of amphiphilic double-decker-shaped polyhedral silsesquioxanes.

Langmuir : the ACS journal of surfaces and colloids (2011-04-16)
Asuman C Kucuk, Jun Matsui, Tokuji Miyashita
ABSTRACT

"Core-corona" type amphiphiles, which comprise double-decker-shaped POSSs (DDSQs) as the core and two or four di(ethylene glycol) (DEG) units as the coronae, have recently been reported to form a stable monolayer at the air-water interface. In this paper, another core-corona amphiphile, 2DEGNH-DDSQ, which has a urethane group at the end of the coronae, was synthesized to elucidate the effects of hydrogen bonding on monolayer properties. The surface pressure-area isotherm and Brewster angle microscopy revealed that 2DEGNH-DDSQ initially formed rodlike assemblies. They subsequently coalescence to form a uniform monolayer with compression. Actually, 2DEGNH-DDSQs are well ordered in the rodlike assembly because of the strong hydrogen bonds among the urethane groups, as confirmed by FT-IR spectra. Although the monolayer was not transferred onto a solid substrate, mixing of 2DEGNH-DDSQ with 2DEG-DDSQ, which has already been reported to form a liquidlike monolayer, overcame this problem. The 1:1 molar mixture of 2DEGNH-DDSQ and 2DEG-DDSQ forms a uniform liquidlike monolayer. The mixed monolayer was transferred onto a solid substrate as a Z-type Langmuir-Blodgett film. Atomic force microscopic (AFM) images of the mixed-bilayer film showed a uniform surface with root-mean-square surface roughness of 0.21 nm. The intermolecular hydrogen bonds between the urethane groups in 2DEGNH-DDSQ and the hydroxyl groups in 2DEG-DDSQ improve the monolayer properties, which enable successful transfer of the LB film.

MATERIALS
Product Number
Brand
Product Description

Supelco
Diethylene glycol, analytical standard
Sigma-Aldrich
Diethylene glycol, BioUltra, ≥99.0% (GC)
Sigma-Aldrich
Diethylene glycol, ReagentPlus®, 99%
Sigma-Aldrich
Diethylene glycol, puriss. p.a., ≥99.0% (GC), colorless
Supelco
Diethylene glycol, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Diethylene glycol, SAJ first grade, ≥98.0%