Polyhedral Oligomeric Silsesquioxanes:  A New Class of Amphiphiles at the Air/Water Interface

Deng, Jianjun; Polidan, Joseph; Hottle, John R.; Farmer-Creely, Catherine E.; Viers, Brent D.; Esker, Alan R.

doi:10.1021/ja027860v

Cited by 81 publications

(93 citation statements)

References 16 publications

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“…It is obvious from Figure 6 that Cy 8 T 8 molecules form multilayers even at low surface pressure (Π ≈ 0 mN m -1 ); thus, it is impossible to estimate a reasonable area per POSS molecule from the figure. This behavior is expected on the basis of previously reported data for octaisobutyl-POSS 23,24 and the completely hydrophobic character of Cy 8 T 8 . On the other hand, it is possible to estimate the area each cyclohexyl-substituted POSS cage occupies from Cy 7 T 7 (OH) 3 since these molecules form stable monolayers and feature nearly identical structures.…”

Section: Compression Isotherm Studies Of Peg Vs Poss-peg-posssupporting

confidence: 84%

Telechelic Poly(ethylene glycol)−POSS Amphiphiles at the Air/Water Interface

Lee

Deng

et al. 2007

Macromolecules

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Combining two non-surface-active building blocks, oligomeric poly(ethylene glycol) (PEG) and a completely hydrophobic polyhedral oligomeric silsesquioxane (POSS) cage, creates amphiphilic telechelic polymers (POSS-PEG-POSS), which exhibit surface activity at the air/water (A/W) interface. POSS moieties serve as the hydrophobic groups for hydrophilic PEG chains of different number-average molar mass (1, 2, 3.4, 8, and 10 kg mol -1 ). For short PEG chains (1, 2, and 3.4 kg mol -1 ), insoluble monolayers form, whereas POSS end groups were not sufficiently hydrophobic to keep higher molar mass hydrophilic PEG blocks (8 and 10 kg mol -1 ) at the A/W interface. Thermodynamic analyses of the 1, 2, and 3.4 kg mol -1 POSS-PEG-POSS via surface pressurearea per monomer isotherms indicate that the POSS end groups reside at the A/W interface and that the PEG chains are squeezed into the subphase with increasing surface pressure. This conclusion is supported by X-ray reflectivity studies on Y-type Langmuir-Blodgett multilayer films which reveal a double-layer structure with a double-layer spacing of about 3.52 nm. These findings provide a strategy for producing new surface active species from non-surface-active precursors.

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Section: Compression Isotherm Studies Of Peg Vs Poss-peg-posssupporting

confidence: 84%

Telechelic Poly(ethylene glycol)−POSS Amphiphiles at the Air/Water Interface

Lee

Deng

et al. 2007

Macromolecules

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“…The uniform reflected area was attributed to liquid expanded phase, and the dots may consist of POSS nanocrystals because of their high aggregation property. 11,12 The BAM images of 4DEGNH DDSQ resemble those of 4DEGDDSQ. This result is quite different from that observed in the case of 2DEGDDSQ, which has two DEG units as the coronae.…”

mentioning

confidence: 94%

Monolayer Property of “Core–Coronae” Type Hybrid Amphiphile with Four Hydrogen-bonding Groups at Air–Water Interface

Matsui

Küçük²,

Miyashita³

2012

Chemistry Letters

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A "corecoronae" type hybrid amphiphile, which contains urethane unit in the coronae was synthesized, and the monolayer property was studied. The hybrid amphiphile formed a liquidlike monolayer at the airwater interface. The urethane groups formed intramolecular hydrogen bonds.Recently, organicinorganic hybrid materials have attracted considerable attention because they show unique mechanical and physical properties.1 The organization of organic fragments and inorganic fragments at molecular levels is an important factor that determine their unique properties.2 The bottom-up approach such as layer-by-layer 3 and LangmuirBlodgett (LB) techniques can be used to assemble hybrid materials. 4 For manipulating molecules using LB technique, amphiphilic materials are required.5 Recently, we reported hybrid amphiphilic materials based on double-decker-shaped silsesquioxanes (DDSQ). 68 The hybrid amphiphiles are "corecoronae" type because they are composed of DDSQ as an inorganic core and di(ethylene glycol) (DEG)s as the organic coronae. We have reported that DDSQ with two (2DEGDDSQ) or four DEG (4DEGDDSQ) units form a uniform monolayer at the airwater interface.6 Moreover, a unique rod-like assembly was formed when a urethane group was attached at the end of DEG groups in 2DEGDDSQ.7 FT-IR spectroscopy indicated that strong intermolecular hydrogen bonding between the urethane groups induced the formation of a rod-like assembly. However, the properties of urethaneattached 4DEGDDSQ assembly were not reported. In this study, we synthesized 4DEGNHDDSQ, which contains a urethane group at the end of four DEG units. The urethane group was selected because urethane groups form strong hydrogen bonds. The effect of the hydrophilic end group on the monolayer property of the four-armed corecoronae-type amphiphile was studied.4DEGNHDDSQ was synthesized by direct hydrosilylation of DDSQ with di(ethylene glycol) vinyl ether, followed by the reaction of OH groups with ethyl isocyanate (Scheme 1). 9Direct hydrosilylation was carried out in toluene at 0°C using platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane (Karstedt's catalyst; 50 ppm) as catalyst. The crude product was purified by silica gel column chromatography eluted with THF/n-hexane. The purified compound was dissolved in toluene at 0°C and stirred in an argon atmosphere. Then, ethyl isocyanate was added dropwise into the reaction mixture. The reaction was carried out at room temperature for 1 day. Unreacted isocyanate was removed by evaporation. Figure 1 shows the FT-IR spectra of the initial compounds (4DEG DDSQ) and the obtained compound (4DEGNHDDSQ). The OH peak related to DEG units at 3444 cm ¹1 band shifts at 3343 cm ¹1 , which is attributed to the NH vibration in 4DEGNH DDSQ. Moreover, peaks related to the carbonyl peak appeared at 1720 and 1707 cm ¹1 ( Figure S2).10 1 H NMR spectrum of 4DEGNHDDSQ was recorded in CDCl 3 . The 1 H NMR spectrum of the product indicated the presence of NH (4.7 ppm) and CH 3 (1.1 ppm) and the disappearance of OH (2.0 ppm) ( Figure S1). 10...

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“…In this case, the results described as the effect of the thermal barrier and formation of interconnected layers were suggested in the incorporation of octafunctional POSS, i.e., an average of eight functional groups at the vertices of the cage. However, other studies using monofunctional POSS have demonstrated that the hybrid cages tend to exhibit amphiphilic features [12,14]. This observation was made based on the fact that POSS tends to form micelles to relieve the interfacial tension between the inorganic cages and the resin (which interact with the organic groups bonded at the vertices of the cages) [14].…”

Section: Introductionmentioning

confidence: 99%

“…This observation was made based on the fact that POSS tends to form micelles to relieve the interfacial tension between the inorganic cages and the resin (which interact with the organic groups bonded at the vertices of the cages) [14]. This difference in functionality could affect the response in thermal stability compared with the formation of layers [2,3,9] and micelles by POSS [12,14]. The aim of this work is to evaluate the influence of the formation of POSS (glicydilisobutyl-POSS) micelles on the thermal stability and the kinetic degradation of the epoxy resin.…”

Section: Introductionmentioning

confidence: 99%

Effect of glycidylisobutyl–POSS on the thermal degradation of the epoxy resin

2015

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In this study, polyhedral oligomeric silsesquioxane glycidylisobutyl-POSS was dispersed in an epoxy resin (DGEBA) using ultrasound, and the thermal degradation was investigated by the Flynn-Wall-Ozawa and Criado methods using thermogravimetric analysis. The TEM analysis indicated higher polyhedral oligomeric silsesquioxane (POSS) dispersion in spherical shape. The POSS dispersion was associated with the formation of micelles as a result of their hybrid character. The addition of POSS did not change the degradation of the resin until *380°C, and above this temperature, increase in the thermal stability was observed. The kinetic results revealed that the addition of POSS decreased E a values primarily to 10 % POSS and did not affect the mechanism of degradation for all contents. The reduction in E a was associated with the easier breaking of bonds at the interface of the DGEBA/POSS nanocomposite. The thermodynamic parameters suggested an increased ''degree of arrangement'' for the formation of an active complex during the degradation process and corroborate the lower E a values. The results suggest that the addition of POSS is able to cause an effect of thermal barrier at higher temperatures without affecting the homogeneity of the microstructure of the cured resin.

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Polyhedral Oligomeric Silsesquioxanes: A New Class of Amphiphiles at the Air/Water Interface

Cited by 81 publications

References 16 publications

Telechelic Poly(ethylene glycol)−POSS Amphiphiles at the Air/Water Interface

Telechelic Poly(ethylene glycol)−POSS Amphiphiles at the Air/Water Interface

Monolayer Property of “Core–Coronae” Type Hybrid Amphiphile with Four Hydrogen-bonding Groups at Air–Water Interface

Effect of glycidylisobutyl–POSS on the thermal degradation of the epoxy resin

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