Abstract
Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(CH2-CHSi(OMe)3)n-RF (RF-(VM)n-RF)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)3] under alkaline conditions to afford the corresponding fluorinated oligomeric silica nanocomposites containing gluconamide units [RF-(VM-SiO3/2)n-RF/Glu-SiO3/2]. These obtained nanocomposites were applied to the surface modification of glass to provide the unique wettability characteristics such as highly oleophobic/superhydrophobic and highly oleophobic/superhydrophilic on the modified surfaces under a variety of conditions. Such a highly oleophobic/superhydrophobic characteristic was also observed on the modified PET (polyethylene terephthalate) fabric swatch, which was prepared under similar conditions, and this modified PET fabric swatch was applied to the separation membrane for the separation of the mixture of fluorocarbon oil and hydrocarbon oil. The RF-(VM-SiO3/2)n-RF/Glu-SiO3/2 nanocomposites, which were prepared under lower feed amounts of basic catalyst (ammonia), were found to cause gelation in water. Interestingly, it was demonstrated that these gelling nanocomposites are also applied to the surface modification of the PET fabric swatch to give a highly oleophobic/superhydrophobic characteristic on the surface. On the other hand, the modified glass surfaces treated with the corresponding nanocomposite possessing no gelling ability were found to supply the usual hydrophobic characteristic with a highly oleophobic property. More interestingly, the wettability change on the modified PET fabric swatch from highly oleophobic to superoleophilic was observed, and remained superhydrophobic after immersing the modified PET fabric swatch into water.
Highlights
It is well known that fluoroalkanoyl peroxide [RF -C(=O)OO(O=)C-RF : RF = fluoroalkyl group]is a useful tool for the synthesis of two-fluoroalkyl end-capped oligomers [RF -(M)n -RF : M = radical polymerizable monomers] [1,2,3]
Is a useful tool for the synthesis of two-fluoroalkyl end-capped oligomers [RF -(M)n -RF : M = radical polymerizable monomers] [1,2,3]. These fluoroalkyl end-capped oligomers are attractive polymeric materials because they can exhibit a variety of unique properties such as high solubility, surface active properties, and nanometer size-controlled self-assembled molecular aggregates through the aggregation of end-capped fluoroalkyl segments in oilgomers, which cannot be achieved by the corresponding non-fluorinated and randomly fluoroalkylated polymers [4,5]. In these fluoroalkyl end-capped oligomers, especially, fluoroalkyl end-capped oligomers containing various hydroxyl segments such as monool, triol, and tetraol can cause gelation in water and polar organic media such as methanol and ethanol, whose behavior is governed by the synergistic interactions of the aggregation of fluoroalkyl segments within oligomers and the intermolecular hydrogen bonding related to the hydroxyl segments [6,7,8,9]
We have studied the surface roughness of the modified surfaces possessing a (Run 1 in Table 2) and usual oleophobic similar wettability and usual and hydrophobic characteristics (Run 8 in Table 2) including the original fluoroalkyl end-capped oleophobic and hydrophobic characteristics (Run 8 in Table 2) including the original fluoroalkyl endvinyltrimethoxysilane oligomeric silica nanoparticles [RF -(VM-SiO3/2 )n -RF ], for comparison
Summary
These fluoroalkyl end-capped oligomers are attractive polymeric materials because they can exhibit a variety of unique properties such as high solubility, surface active properties, and nanometer size-controlled self-assembled molecular aggregates through the aggregation of end-capped fluoroalkyl segments in oilgomers, which cannot be achieved by the corresponding non-fluorinated and randomly fluoroalkylated polymers [4,5] In these fluoroalkyl end-capped oligomers, especially, fluoroalkyl end-capped oligomers containing various hydroxyl segments such as monool, triol, and tetraol can cause gelation in water and polar organic media such as methanol and ethanol, whose behavior is governed by the synergistic interactions of the aggregation of fluoroalkyl segments within oligomers and the intermolecular hydrogen bonding related to the hydroxyl segments [6,7,8,9].
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